Thanks for letting us know that the new master cylinder wasn't the solution. Some guys would either just say the brakes are fixed, or just not upload the video at all if the 'fix' fails.
FYI for any early Duramax owners, if you need a new brake booster, get the newer one for 2011+ trucks. Bolted right up to my 2004 LB7 and I have WAY stronger brakes without all the sponge feeling. And the new and improved booster is half the cost of the OE part. Eric, love the videos man. Thanks for posting!
One thing I'm not sure Eric talked about and that is to make sure the brake booster push rod is adjusted properly. In some cases there is an adjustable end on the push rod and over the years of use, they sometimes screw themselves back thereby increasing the distance the brake pedal has to travel before it contacts the master cylinder. If you check this, it should be adjusted so that when the master cylinder is bolted to the booster, that the end of the push rod is seated fully but not depressing the master cylinder piston.
Hey Eric! For what its worth, I really hope you keep this truck relatively stock. You've already got a performance vehicle project and this truck is a real gem of its era. It's a beauty!
I had a soft pedal in my Dodge since the car was new. Drove me nuts. Bled it 10 times. Replaced MC. New calipers, etc... One day, the left front brake locked up after a fast stop. New caliper would not release. In desperation, I loosened the banjo bolt to relieve pressure. That is when I noticed a bulge in the rubber brake hose. It had an anurism internally that finally manifested itself by blocking fluid return path to MC. A new hose was installed, and wow, what a difference in pedal feel and position. Rock hard and excellent braking ever after!
Great videos! I watched this one because I had the exact same issue with my 99 GMC Sierra. I changed everything! Discovered while changing the front calipers that I wasn't getting any gravity bleed from the hose coming from the brake line. Changed those out on the front and the pedal came back!
Eric- check the abs module. It's that thing below the master cylinder, that is held down by the same bolts. If the valve in it is stuck open, it will cause that spongy pedal!
My friends installed a newer model master cylinder and front shocks. I came in a few weeks later and finished the job, by installing the rear shocks, new drum shoes, and bled the entire brake system. The brake fluid was really dirty! The job was a success! No more spongy brake pedal! My very young friend and his girl are taking a business trip up to northern California for work and leisure after work. Take good care bro! 👍
I had a 94 1500 through college. Had to do this exact same job. Couldn't have done without watching Eric's video on how to bench bleed a master cylinder. Thanks Eric!
As a youtuber. I'm glad that you are legit and real. So many other youtubers would've acted like it was 100% fixed BUT you stayed true and say "hey I tried this and it didn't work" Great job. So many channels look at youtube like an "tv reality show" where they can makeup things and lie.
I had a similar problem on an 02 Mercury Mountaineer but the pedal was low too. I checked / bled everything & was going to replace the master cylinder but I found your video on solving a similar problem on a Honda. Took the Merc to a safe location, ran it up to speed and tried to lock the brakes. That "exercised" the ABS and solved the problem.
Thanks to your video you gave me the idea to bleed the master cylinder. Doing it by myself, I used a cut off 2x4 to hold the pedal down after pumping a few times, then back to the master cylinder to bleed , one at a time 3 times each. Engine off. Success 👌🏾
Air pockets get stuck in the ABS module. There’s a special tool to hold the pin on the abs module (behind small rubber cap on abs module itself) in leaving the ABS module open when you’re bleeding the system. It’s a common issue with these OBS chevys but not many people know about it.
I have owned quite a few GMT400s for almost 20years and didn't figure this out till a couple years ago. I went through a lot of fluid and stopping in gravel till someone showed me.
Been there, done that 20+yrs ago... problem still returns eventually... I simply bypassed the whole abs setup, brakes are now old school, no anti-lock, and work fine, and no brake light on because of the abs being gone...btw, brake light will still work for parking brake, etc....
My original master cylinder was working perfectly fine but the fluid was very dark even after the brake flush. I noticed my rear wheel cylinder was leaking so i wanted to baby my truck and install a brand new ACDelco master cylinder and new wheel cylinders. Oh boy I had a horrible time bleeding the rear drum brakes. Brake pedal was going all the way to the floor. I searched TH-cam videos to help me with my issue. So it seemed like ABS control module might have air. So i kept and kept bleeding it without luck. I went to my junk yard location to find a used ABS module. I spend almost half of day looking for one until i found one. Went home tried on and same results. I also purchased another proportioning valve because it might be the problem. Installed and same results. My brake light was on and almost no pressure to the rear lines. So I came across to a video explaining how to rest the proportioning valve to keep it open so fluid could travel to the rear line and same results. I bought a lot of bottles of brake fluid I spent about 70 dollars on fluid. I could recycle it and reuse it but it was turning dark and green so i didn't want to reuse it. So there were another videos that explained about some wheel cylinders could be bad and have defective seals and it could suction air back to the system. So I purchased another set of wheel cylinders installed them and same results. I was loosing my brain cells. I purchased a 80 dollars brake bleeder and didn't help at all. Same problem pedal all the way to the floor. I gave up and i took it to Firestone to the pros, so they can diagnose the main problem and the truck was there all day and they didn't find the issue. I was told it was because i removed the ABS MODULE and computer. That i needed a new ABS computer and a rebuild the ABS module otherwise i would keep have this issue. They quoted me a leg and arms so no way i could afford it. It was like buying the truck again. I went home all sad and disappointed. They didn't even bother to check the master cylinder because it was brand new and original supposedly. I knew my old was working so I was like you know what ima install it back but honestly i didn't want to because it was old and looked beaten by the years. At this point I didn't care. So I removed the new master cylinder and BOOMS!!! My pressure was there instantly!! My pedal was firm and hard. No more brake light on!! After a week of pure stress finally i could breathe. This part gave me a headache I don't wish this to anybody. I hope you never get to go through this.
I was taught to put short brake lines from the ports back into the reservoir and pump till the bubbles stop. It's always worked for without most of the mess.
I had a similar issue on an 07 Impala for a customer's car who complained of sinking pedal when the vehicle was warmed up. I was about to change the master cylinder, even had it sitting on the bench waiting, and decided I better be 100% correct first. I plugged the two ports with some rubber disks and then threaded the brake lines back in. Rock hard pedal which meant the MC was fine. I saved myself the embarrassment (and cost) of a wrong call. Turned out some MAJOR amounts of scan tool brake bleeding solved the issue of the sinking pedal on that.
Also look into changing out the proportioning valve. And get rid of all that ABS stuff, pump and all. My wife and I learned how to double flare brake lines real quick just to fix the spongy brakes that she had been fighting before she met me. And yes my wife loves working on vehicles ! I'm so lucky 😁
I did that master cylinder swap on my 1996 Chevy Express. Do it! You will not regret it. Brakes feel like a new vehicle. I got my MC at the junkyard for $15 off of a 2002 Suburban.
Likely the isolation/dump valve (aka EH valve, etc). Dealing with this now - suspect air in accumulator, or junk got stuck in valve(s) opening. This explains much (search.. can't post links?). "Kelsey-Hayes RWAL Antilock Brakes" Will try to take it apart and clean (seen nothing on inet about this), but it has a plug in bottom, with a valve/rubber cover like that on proportioning valve (not seen anything about this either) - the iso/dump valve pin under rubber cover didn't pop out like prop.valve pin when pressing brakes. Don't want to swap out for newer model parts (or really see a need to) since pedal wasn't spongy until the LR brake line rusted/broke introduced air into rear lines. These RWAL systems are a PITA, but they worked for a long time. Thanks for video - well done and informative for changing the master cylinder (as you wrote in intro).
My first experience on brakes was a 69 Pontiac Catalina. I ended up replacing everything from the wheel cylinders to the master brake cylinder before I finally got the brakes working right. After that, I could do brakes on any vehicle...and have over my life time. I used to do brake jobs in exchange for home cooked meals and fresh baked bread. It was worth it back then!
Hey! Your videos have helped me many times. I'm happy to help you this time. Turns out the answer is, there's a specialized procedure for bleeding breaks on that particular model. What you have to do is push the brake pedal down once, open up the rear nipple and bleed. Then you have to wait 15 full seconds. Then you put down the brake pedal just once and bleed. On most cars you pump the brake pedal a bunch of times. On those models, your partner has to push the brake pedal to the floor only once. Then you open it up in the rear. We did everything, bled the hell out of the brakes the normal way, but when we followed this procedure we still got black fluid out and lots of bubbles. Completely changed the way the pedal felt. They also want you to bleed the reservoir. They want you to do that by having your partner put their foot down on the brake pedal, and you slightly open the forward most brake line on the brake reservoir. You do that a few times, then you follow the same procedure for the backmost brake line on the brake reservoir. That's your starting point. After that, bleed the rear brakes. But you absolutely have to wait 15 seconds in between! And you cannot pump the brake pedal. It makes it almost impossible to bleed. Have your partner push it down once, hold, flush the back end, close it back up and have your partner release the brake pedal and wait 15 full seconds. Then try again.
I have the same problem , an spongy pedal en poor rear brakes. The problem (and the dashboard warning light is shining) since i changed the brake dot 3 oil after there was to little oil in the reservoir. I will try out your advice !
The NBS Silverado master swap makes a BIG difference in pedal feel on the older trucks. I did this swap on my Tahoe and it was night and day difference. All you need is a master from a 01 and up and an adapter fitting and you get better pedal feel. I later upgraded to the 13 inch 05 up front rotors and calipers since my truck is 4wd, huge increase in braking ability.
The 1990 has the RWAL (rear wheel antilock) system. It's that other module next to the proportioning valve on the bracket next to the master cylinder. Pumb the rear brake line directly to the proportioning valve bypassing the RWAL module. The modules are known to cause a spongy brake feel. My 1990 had this issue and that was the fix. Mine has great pedal feel now.
Eric I appreciate and enjoy your videos. I know you went to a tech or trade school which is far better than shade tree shops. I have been in the trade for well over fifty years; and many authorized Factory approved schools which includes GM Bendix Westinghouse brakes school (air&hydraulic), Cat, Cummins and Detroit Diesel. Well my point is when working on hydraulic brakes I was taught when replacing a wheel cylinder you also replace the apposing cylinder and you gravity or preferably pressure bleed as pumping the brake pedal can create micro bubbles in the fluid; which causes soft/spongy pedal. And the micro bubbles really became a problem after the invention of disc brakes!!!
To start off I would have to say, what a great sense of humor! I thought several of the GM products had an "anti-reverse" valve that doesn't allow you to "pump" the breaks for bleeding. When pumping the breaks, this valve engages and stops the bleeding process. The brake pedal feels harder (until the engine is started), but the air in the lines is never displaced. Not sure on your rig, I have found it on some products. Thanks for taking the time to make the video.
I was having the same issue and thought about doing the same with my suburban, I changed the front ABS sensors instead and it fixed the problem. Brake pedal is way more responsive to what it was before. I would definitely recommend it Eric!
Cool. You could replace the rubber brake lines that run down to the calipers with braided stainless. This helps get the brake pedal feel back. Those old rubber ones start to stretch alot over time.
Delete the ABS module and it's control module. That solves the spongy brake problem on these trucks. Ran into same problem on mine when I changed the rear wheel cylinders. The old ABS on these trucks are not the best and you cannot bleed the AND without a GM original diagnostic computer scan tool.
My buddy’s 03 blazer is doing the same thing. New MC, bench bled, all 4 wheels bled like crazy, still a soft pedal. Although with the vehicle not running you can pump them up and the pedal is rock hard. I’m still leaning towards air in the ABS module.
Absolutely delete RWAL ABS. Cause of serious problems and can actually leave you with no brakes whatsoever. At least disconnect the dump valve solenoid. Brake warning light can be ignored if necessary. By the way if your brake warning light comes on consistently at around 35 mph that usually indicates brake pedal switch needs replacement. May otherwise function properly but has to do with the way it communicates with the electronic module. I know, sounds ridiculous, and it is. RWAL ABS was not good.
And a new brake master cylinder didnt work... Eric, I appreciate your straight forward 100% honesty...b/c I know I'm going to spend money on a new MC and still get a spongy feel. But, you know what I think it is??...if you installed a new brake caliper piston seal it may not 100% seal the old brake caliper b/c a 30 year old caliper changes shape as they age ...
I have a 96 K1500 GMC Yukon, same problem. I did the 99 master cylinder swap, like everyone said to do. Didn't do a damn thing except make my bank account smaller in dollars. I have been told by two GM Line mechanics, that I have to blead the Kelsey Hayes ABS computer. Problem is the only way to do this, is with a OBDII device that has the function built in. To get one that does you have to spend more than I want to. Solution take it to a shop and they will do it for just under what he OBDII device costs. Oh well, the price we pay for rebuilding old Chevy's and GMC's. I love the 94 to 98 Chevy Silverado K15 & 2500 and the GMC counter parts. I have had five of them and have amassed quite a parts store, and learned way more than I should have about how to maintain and service all of them. From replacing engines, Tyranny's, Transfer cases, lifting, and all kinds of customization.
Hey Ericthecarguy I have been in a problem with a 94 Chevy 1500, with a spongy brake pedal, I ended replacing the rear drums and that solve my problem !!!!
Often the rear brake adjustment can solve a soft pedal. However, as mentioned at the beginning of the video, I did that before trying the master cylinder. Glad it worked out for you though.
Why did you have to replace the rear drums to begin with? Were they worn excessively? If they were wouldn't your self adjusters move the brakes shoes closer to the drum surface?
Excellent video. The easy way to fix a brake issue. Easy step by step instructions on this to keep from having issues later with the brakes , great video. Thanks
Excellent explanation throughout the process. Only thing I would say is "OK hold it" does not mean to stop pumping in whatever position the foot is in. It means hold the foot down with pressure and do not release the pressure on the pedal even when the pedal drops.
You got it ETCG. The 88-98 trucks had the “spongy” brake pedal throughout the model years, and all models had it. Alot of guys swap the master cylinder (and brake booster for some) from 99-06 NBS trucks which helps get a firmer pedal. Others ditch the factory ABS and get a proper proportioning valve to help with it as well. Aside that, I am glad to see you are doing videos on the GMT400! Oh, and I had to check to make sure Cameraman Derek didn’t take my shoes... I have the exact same pair. Haha!
That's exactly what I heard. I'm thinking of making another video installing those parts. If that doesn't work, I was going to go with steel braided brake lines. Thanks for the info.
rrcoster I am not too sure. I have driven a few GMT400 trucks, including my current daily driver which is a 98 K1500, and it has done that on all. I have just gotten used to it, I suppose, and can still activate an emergency braking procedure without locking up the wheels (ABS quit working a while back). That being said, I have also driven some GMT800s (99-06 models) and felt that the brakes had the same/somewhat similar feel. Perhaps the 800s were just a tad firmer, but otherwise. Alot of 400 owners that have done the 800 MC Conversion claim to have a better, firmer pedal. I’d like to feel one to see if it is better after all. I hope that if ETCG decides to do this to his 90 Chevy, that he will share with us the findings and conclude if it is better. I wonder if MCs from 07-18 work better too. I also wonder if it is better to get rid of the ABS modules and put the proper proportioning valve and converting the rear to Disc if it would help. All this is just reaching for straws, I suppose.
Chris Jacobs I am sure those do make a difference. I am not real sure why people make a big stink about it, as I have driven a GMT400 for a while, and it has always had this problem. I don’t even consider it a problem. The ABS doesnt work, yet I know how much pedal to give it especially if I need to stop on a dime. At the same time, I havent driven a GMT400 with the conversion done, so I can’t speak for it. I can only go on word of mouth. I guess it all depends on the driver, after all. In any case, steel braided lines may help, and I eventually plan to do that with mine. I am not in a rust belt, so my lines are in great condition. Thanks for the tip! ETCG, you may want to try this first!
I've worked on a fleet of Chevy trucks from 1986 to 2002 model years and they all had spongy pedals since they were new. I experienced the same thing on a first gen Toyota Sienna, which I hated.
On my 2005 GMC Sierra, I had nearly zero braking from a worn wheel hub (bearing) so the ABS speed sensor was "confused". I isolated the problem by pulling the ABS/Brake fuse and brakes were perfect in manual mode. There are so many damn possibilities on modern vehicles. Sometimes I just want to buy an old truck from the 1950's, dammit.
My dream car is a 1963 Chevy Nova 6 cyl 3 speed manual transmission - where the only thing electronic is the radio. These cars ran forever and were cheap /easy to maintain. 😄
Wow, a lottta good tips and ideas but I feel like some people in the comments dont realize that you are a career mechanic and do this for a living. Great video on how to replace the master cylinder and I'm surprised that you didn't get a bunch of you have to bleed brakes this way comments
G'day, Eric! Yes! I second that! "Eric O., would be very proud!!" Thank you for "how to replace, and bleed a master cylinder on a C1500, 1990 5.7L!!" Cheers! :D😊🚚❤️
I've got a 1991 C1500 350tbi and I've always had a great pedal... Never any sponginess, or fade. One thing I did do though was install a set of braided stainless steel lines and that made my pedal rock solid... noticed it for sure!
If that truck has rear ABS, there is a dump valve that gets triggered and air gets caught in or if the rear brakes were ever depleted of brake fluid from a rusted brake line or blown wheel cylinders. May times I thought I had a bad master cylinder when all it needed was a bench bleed. It always works and the brake pedal will be awesome on it Apparently you can also crack a line off the rear ABS valve and open and close it like a bleeder as if it was at a brake. Oh I see now yours has a bleeder at the rear ABS. My later model does not. Mine stops fine. Stock master, I keep the rear drums adjusted fairly tight and run performance front brake pads. Used some new ACD brake shoes too, they have alot of bite compared to these cheap ones I have. basically if you have a air pocket in that rear ABS solenoid/ dump valve the pedal is going to suck no matter what you do. Sometimes mine gets spongy all of a sudden but firms up. One day I am going to delete the rear ABS. All it needs is a few short brake lines made up to patch it in. www.aa1car.com/library/abs_kelseyhayes_rwal.htm
i put new front rubber lines on my 94 gmc and that made a real difference hope this helps and they got the nice stainless steel lines for these at orilles for like $85 for all 3 lines also i had sponge brake on a 96 jeep gc and i took off the abs relay and it was much better i have yet to lock the brakes up at all
I read somewhere a long time ago that spongy pedal feel is usually the brake booster diaphragm leaking and giving out. As already concluded, you changed the master cylinder and the only other part that could be problematic is the booster. Great vid as always and thanks for sharing
Interesting, Eric. But there is another possibility , air in the ABS HCU. With some vehicles, the hcu has to be run with the scantool to push air out of the unit, then the rest of the system has to be bled. If the hcu is not actuated, it is very difficult to bleed the air out of the system. In your case, your truck has an RWAL system. Also, my brake bleeding sequence preference is to look up the sequence and do it that way. For those who are not aware; usually the sequence starts with the corner farthest from the master, brake line wise. It is because of how the lines are run. For example, the lines on my 95 Neon run from the master to the firewall, travel along the firewall to the right side of the car, then run down under the car, and run to the rear on the right side. That makes the left rear the longest line on the car, and the furthest from the master. The bleeding sequence starts with the left rear, then to right front, then to right rear, then finally the left front.
I have a 1994 Chevy C1500 and have the exact brake issue you have Eric. I know others that have the same issue as well. One guy had a brake shop tell him that is just the nature of these trucks. I also saw on TH-cam someone say the problem is the rear brake anti lock is causing the spongy brake and bypassing this but rerouting a brake line fixes the problem but I haven’t tried that yet.
I heard the hissing sound when derik was pushing on the brake pedal and knew it wasn't fixed. Either brake booster or leaking vacuum line, sometimes the foam if you have it is degraded and you will hear the hissing.Glad your back missed your knowledge of cars brother. Oh nice can for spraying brake cleaner, just put some air in it and spray away.
That's not the issue, it's just how some systems sound. If the booster was bad, the brake pedal would be extremely hard because there would be no assist. I'm thinking of getting the new parts and trying it out to see if that solves the problem.
I have had success with eliminating the the “spongy petal” by only pushing the piston into the master 1/4 to 3/8 of an inch. This with also not putting the petal to the floor just pumping it 3” approx and holding it. This was a “fix” from an instructor that observed the the length of movement of the plunger on a Raybestos bleader bench...
Hey Eric i saw your video and im sorry to hear about your troubles. If your truck has ABS air can get trapped in the ABS module. There is actually a "brake bleed" function that bleeds the abs module using a scan tool. I use an Autel DS808 but im sure there are other scanners capable of this function. If you can borrow one from someone give it a try. I had the same issue on a 99 suburban and it worked for me.
Hold the phone on any brake modifications you do!!! I have a '98 that I'm LS swapping. I'm installing a Wilwood 1" master cylinder, ABS delete, and a Little Shop MFG rear disc conversion. I'll let you know how it goes. If you don't like the pedal feel, I think I know what you mean. When you first slam the brake as hard as you can, the system doesn't build pressure to stop the vehicle. Slower application of the pedal works just fine. On modern trucks, they're waaay over-boosted so the pedal is super mushy. I know the feel you're going for. "You like it when you can push the pedal as hard as you can, but without the pedal going closer to the floor. You want to feel like you're standing on top of a spinning smoothly machined iron disc. You want to be able to feel if your rotors are warped by how they modulate the pedal."
Bleed the abs module directly under the master cylinder. My 89 has that old school rwal (kelsey hayes I believe), which can still have air even after a full bleed on the rest of the system. Kept looking at it on your video, the little bleeder there (just above the yellow paint mark).
Great video Eric. It’s very informative. I just had my brakes become soft the other day on my 91 C1500 after having to brake hard to avoid an accident. A friend helped me bleed the brakes which did not fix it. He suggested exactly what you did at the end of your video so that’s my next step.
I remember back in the late “60s” when I was learning the trade, I left a”drop” of brake fluid on the fender of a black hearse. Later when I went back to wipe off the fluid, it left a bright shiny bare metal spot on the fender where the fluid sat.🤭
I never bench bleed master cylinders. I put a vacuum on the reservoir, take it off and refill. Do that a couple times then put a vacuum on while pumping pedal and that usually gets all the air out. Many car manufacturers vacuum bleed the brake systems on the assembly lines. No mess and a little faster.
Good timing. My 2000 Buick LeSabre had this issue (no brakes, dry lines) and swapping master cylinders also fixed it. That said, I didn't bleed the wheels after, so maybe I screwed up there (or I missed a leak, it's a real rust bucket).
I should've hung onto my '94 K1500. Biggest mistake I ever made was selling it, and buying an '07 Silverado 1500. The '94 was 100x more reliable! With that in mind, I'd keep that one stock, and just drive it until the body falls off. I sold my '94 with 266k miles, and was STILL running like a top! Also had a more quiet interior than my brand new truck did. OE u-joints made it 222k miles. May not have had much top end power, or a very good ride, but at least it didn't cost me an arm and a leg to keep it going ... after spending an arm and a leg for it, like the Silverado! GM ain't what she used to be, that's for sure. :( Anyway - great vid! Gotta run - time to refill my IV bag with brake clean ... 😁
94-98 was the best years to buy because GM was working hard to compete with the Toyota trucks coming into the market. Some of the best trucks ever made.
may daily work van is a 92 astro..i will never sell it..most reliable vehicle i have ever owned and i work her every day...easy to diagnose and fix..those old chevys only had like 5 sensors that could go bad lol
Remember that Astro is equipped with a fuel pump that is guaranteed to fail. I also like the Astro (but the last model only) I am not a fan of TBI and the last model came with the 4.3 and multi port injection. I made a good bit of money working on Astro vans (Chevrolet Dealer in Tucson AZ) My area was light line, AC, electrical and interior trim, rounded out by new car accessories. Not everything in the garage is heavy line, brakes,oil changes. Some shops continue to force mechanics to be "bumper to bumper" mechanics. This is a policy I will not work under. I just do not hire on with firms that require bumper to bumper work.
I have a 1995 suburban that gets that spongy feel too. Once in a while, if I hit the brakes hard enough while backing up, or have adjusted the rear shoes myself, the brakes get really good and she'll stop on a dime. I've done water crossings a few times as well with it, and then the brakes REALLY work for a while afterwards (until they fully dry back out anyways). I subscribed just to see if you do that brake upgrade to the gmt800 stuff, and i really like the clarity with which you present yourself. For the cost of brake fluid, I do a complete flush whenever I change calipers/cylinders or buy a used vehicle. A lot of people don't realize that brake fluid is actually a consumable that needs to be replaced due to water absorption. I have a little one man brake bleeder that I use for the work. (essentially a jar with a hose that goes to the bottom of said jar that ensures air isn't sucked back in when releasing the pedal. Mine is a little plastic deal with a magnet so that I can place it higher than the bleed screw.)
Good video... I was taught when bleeding breaks to always start at the brake that is the furthest away from the master cylinder, then the next furthest and so on.
I like how at the end of the video, you admit that it didn't solve your problem. Imagine someone following your video instructions and ending up with the same results 🤣🤣🤣
81 c10 has a firm pedal. Must be combination of the master cylinder design and the size of the booster. Always wondered why some newer cars you barely touch the pedal and it grabs.. then others are softer.
I did the exact same thing to my truck 6 months ago and got the exact same result. You might not be driving it enough to realize, but another common thing is for the truck to be a little late on releasing the Driver's side brake disk, or not completely release at all. Check it out next time if you've got time. I never found a fix for this problem either, and I've replaced everything short of the brake lines.
I had an 88 Chevy regular cab, short step side pickup. 350 V-8. I drove that truck everyday for 11 years. Kept it in top mechanical condition. Then I got a suer dear on a 95 Dodge ram 2500 with the cummins 12 valve. Ended up selling the chevy and eventually sold thr dodge, now drive a 98 dodge ram1500 with a 318...good truck, only had it a bit over 7 years. I kick myself everyday for ever selling the littli 88 chevy. It was the best truck I ever owned.....oh well, they say hind sight is 20/20.....
I figured it out......was going to replace my master cylinder from AutoZone with a warranty replacement .......glad they didn't have it ,in stock.....went orieley auto parts,bought a 100 persent new master cylinder.....now have firm peddle ,not spongy foot pressure.i figured new would have firm new inner springs.
I had the exact same issue with my 90 1500 Suburban. I watched one of you earlier videos on master cylinder bleeding and was ready to make it happen. The instructions that came with my new master cylinder told me to leave the plugs in and gently press the plunger until it stopped bubbling. After bleeding all the lines, it all worked out fine and the peddle no longer sinks to floor at a red light. Like some others have said in the comments, the brakes still aren't as firm as they should be.
Do the late model master cylinder swap he talked about. I did on my 96 Express. I got it off of a 2002 Suburban. It's unbelievable the difference it makes in pedal feel.
Maybe consider replacing the old rubber brake lines. They degrade over time and tend to balloon outward instead of directing the pressure toward the brake pistons.
Seriously, brake lines can be an issue, but if you have that 80's style square capped master cylinder, they are known for spongy pedal feel. I'm willing to bet once you replace all the brake lines, you'll still have the crappy pedal. It's just a design flaw that was fixed on later models with the newer style master cylinder
i've had to do more master cylinders on chevy trucks than i even want to think about.....a little trick i have done to get the air out of the lines is,i will take a front and rear wheel off,and have someone push the caliper piston back in with a c clamp while i loosen the line at the master cylinder. i do bench bleed the master with brass fitings and clear tubing before hand.
I have the same truck. There are four things you can do on these trucks for better brake feel, in order from bargain to bankrupt. 1: ABS delete. 2: Rear disc conversion. 3: 1" master cylinder. 4: Use a rear disc conversion with a 2" D154 caliper and all of the aforementioned mods. 4.5: Front caliper mod. Replace the front pistons with stainless cylinders that don't have notches cut in them.
The bell has to have those two "thingies" over it. It will say at the bottom left of the page "You will get all the notifications". Otherwise it would say "You will get notifications from time to time" and that's probably what you have set it to.
The ABS units tend to be a problem on these. I had removed mine on my 1994 GMC Safri AWD. They wanted $300 bucks to replace it. Nuts! But it made a world of difference
Nice job..excellent video. Happy I watched your video. Had I not viewed your video I would of had a world of trouble because I would of not benched bleed out the master cylinder .
Thanks for letting us know that the new master cylinder wasn't the solution. Some guys would either just say the brakes are fixed, or just not upload the video at all if the 'fix' fails.
I'm 42 yrs old. Have done all my own work forever and never had to replace a master cylinder.
Great process. Nice explanations. Thanks!
FYI for any early Duramax owners, if you need a new brake booster, get the newer one for 2011+ trucks. Bolted right up to my 2004 LB7 and I have WAY stronger brakes without all the sponge feeling. And the new and improved booster is half the cost of the OE part.
Eric, love the videos man. Thanks for posting!
Man, I miss watching his videos. Down to earth, honest mechanic and person.
Did he retire from making videos
@@veezybee23 I believe he did.
Damn.
One thing I'm not sure Eric talked about and that is to make sure the brake booster push rod is adjusted properly. In some cases there is an adjustable end on the push rod and over the years of use, they sometimes screw themselves back thereby increasing the distance the brake pedal has to travel before it contacts the master cylinder. If you check this, it should be adjusted so that when the master cylinder is bolted to the booster, that the end of the push rod is seated fully but not depressing the master cylinder piston.
Hey Eric! For what its worth, I really hope you keep this truck relatively stock. You've already got a performance vehicle project and this truck is a real gem of its era. It's a beauty!
I had a soft pedal in my Dodge since the car was new. Drove me nuts. Bled it 10 times. Replaced MC. New calipers, etc... One day, the left front brake locked up after a fast stop. New caliper would not release. In desperation, I loosened the banjo bolt to relieve pressure. That is when I noticed a bulge in the rubber brake hose. It had an anurism internally that finally manifested itself by blocking fluid return path to MC. A new hose was installed, and wow, what a difference in pedal feel and position. Rock hard and excellent braking ever after!
Great videos! I watched this one because I had the exact same issue with my 99 GMC Sierra. I changed everything! Discovered while changing the front calipers that I wasn't getting any gravity bleed from the hose coming from the brake line. Changed those out on the front and the pedal came back!
Eric- check the abs module. It's that thing below the master cylinder, that is held down by the same bolts. If the valve in it is stuck open, it will cause that spongy pedal!
Great video Eric. And welcome back!!! This Industry needs Tech's like you and all the Proffesional Tech's that are helping out DIYERS.
My friends installed a newer model master cylinder and front shocks. I came in a few weeks later and finished the job, by installing the rear shocks, new drum shoes, and bled the entire brake system. The brake fluid was really dirty! The job was a success! No more spongy brake pedal! My very young friend and his girl are taking a business trip up to northern California for work and leisure after work. Take good care bro! 👍
I had a 94 1500 through college. Had to do this exact same job. Couldn't have done without watching Eric's video on how to bench bleed a master cylinder. Thanks Eric!
Love the out take, Eric. The best thing about Eric is that he uses real world procedures. Glad you're back !!!!!
was he in jail?
Zak
As a youtuber. I'm glad that you are legit and real. So many other youtubers would've acted like it was 100% fixed BUT you stayed true and say "hey I tried this and it didn't work" Great job. So many channels look at youtube like an "tv reality show" where they can makeup things and lie.
I had a similar problem on an 02 Mercury Mountaineer but the pedal was low too. I checked / bled everything & was going to replace the master cylinder but I found your video on solving a similar problem on a Honda. Took the Merc to a safe location, ran it up to speed and tried to lock the brakes. That "exercised" the ABS and solved the problem.
Thanks to your video you gave me the idea to bleed the master cylinder. Doing it by myself, I used a cut off 2x4 to hold the pedal down after pumping a few times, then back to the master cylinder to bleed , one at a time 3 times each. Engine off. Success 👌🏾
Air pockets get stuck in the ABS module. There’s a special tool to hold the pin on the abs module (behind small rubber cap on abs module itself) in leaving the ABS module open when you’re bleeding the system. It’s a common issue with these OBS chevys but not many people know about it.
I have owned quite a few GMT400s for almost 20years and didn't figure this out till a couple years ago. I went through a lot of fluid and stopping in gravel till someone showed me.
Whats the special tool?
Is there a video?
Been there, done that 20+yrs ago... problem still returns eventually... I simply bypassed the whole abs setup, brakes are now old school, no anti-lock, and work fine, and no brake light on because of the abs being gone...btw, brake light will still work for parking brake, etc....
There's no abs on that truck
My original master cylinder was working perfectly fine but the fluid was very dark even after the brake flush. I noticed my rear wheel cylinder was leaking so i wanted to baby my truck and install a brand new ACDelco master cylinder and new wheel cylinders. Oh boy I had a horrible time bleeding the rear drum brakes. Brake pedal was going all the way to the floor. I searched TH-cam videos to help me with my issue. So it seemed like ABS control module might have air. So i kept and kept bleeding it without luck. I went to my junk yard location to find a used ABS module. I spend almost half of day looking for one until i found one. Went home tried on and same results. I also purchased another proportioning valve because it might be the problem. Installed and same results. My brake light was on and almost no pressure to the rear lines. So I came across to a video explaining how to rest the proportioning valve to keep it open so fluid could travel to the rear line and same results. I bought a lot of bottles of brake fluid I spent about 70 dollars on fluid. I could recycle it and reuse it but it was turning dark and green so i didn't want to reuse it. So there were another videos that explained about some wheel cylinders could be bad and have defective seals and it could suction air back to the system. So I purchased another set of wheel cylinders installed them and same results. I was loosing my brain cells. I purchased a 80 dollars brake bleeder and didn't help at all. Same problem pedal all the way to the floor. I gave up and i took it to Firestone to the pros, so they can diagnose the main problem and the truck was there all day and they didn't find the issue. I was told it was because i removed the ABS MODULE and computer. That i needed a new ABS computer and a rebuild the ABS module otherwise i would keep have this issue. They quoted me a leg and arms so no way i could afford it. It was like buying the truck again. I went home all sad and disappointed. They didn't even bother to check the master cylinder because it was brand new and original supposedly. I knew my old was working so I was like you know what ima install it back but honestly i didn't want to because it was old and looked beaten by the years. At this point I didn't care. So I removed the new master cylinder and BOOMS!!! My pressure was there instantly!! My pedal was firm and hard. No more brake light on!! After a week of pure stress finally i could breathe. This part gave me a headache I don't wish this to anybody. I hope you never get to go through this.
Im going through this right now, an almost exact sequence of parts thown at it. so just get another master cylinder?
I was taught to put short brake lines from the ports back into the reservoir and pump till the bubbles stop. It's always worked for without most of the mess.
I had a similar issue on an 07 Impala for a customer's car who complained of sinking pedal when the vehicle was warmed up. I was about to change the master cylinder, even had it sitting on the bench waiting, and decided I better be 100% correct first. I plugged the two ports with some rubber disks and then threaded the brake lines back in. Rock hard pedal which meant the MC was fine. I saved myself the embarrassment (and cost) of a wrong call. Turned out some MAJOR amounts of scan tool brake bleeding solved the issue of the sinking pedal on that.
Also look into changing out the proportioning valve. And get rid of all that ABS stuff, pump and all. My wife and I learned how to double flare brake lines real quick just to fix the spongy brakes that she had been fighting before she met me. And yes my wife loves working on vehicles ! I'm so lucky 😁
I did that master cylinder swap on my 1996 Chevy Express. Do it! You will not regret it. Brakes feel like a new vehicle. I got my MC at the junkyard for $15 off of a 2002 Suburban.
Kevin Vance did you replace the brake booster also or just the brake master cylinder?
@@alexmann25 Following, Same question. Both or just the master cylinder.?
Likely the isolation/dump valve (aka EH valve, etc). Dealing with this now - suspect air in accumulator, or junk got stuck in valve(s) opening. This explains much (search.. can't post links?). "Kelsey-Hayes RWAL Antilock Brakes"
Will try to take it apart and clean (seen nothing on inet about this), but it has a plug in bottom, with a valve/rubber cover like that on proportioning valve (not seen anything about this either) - the iso/dump valve pin under rubber cover didn't pop out like prop.valve pin when pressing brakes.
Don't want to swap out for newer model parts (or really see a need to) since pedal wasn't spongy until the LR brake line rusted/broke introduced air into rear lines. These RWAL systems are a PITA, but they worked for a long time. Thanks for video - well done and informative for changing the master cylinder (as you wrote in intro).
I put a 99 Silverado brake booster on my 1993 C1500 and it works amazing. No more spongy pedal.
Good to know
My first experience on brakes was a 69 Pontiac Catalina. I ended up replacing everything from the wheel cylinders to the master brake cylinder before I finally got the brakes working right. After that, I could do brakes on any vehicle...and have over my life time. I used to do brake jobs in exchange for home cooked meals and fresh baked bread. It was worth it back then!
I’m literally doing brakes in my 92 today! Thanks Eric you’re the man
92 truck!? Nice! How many miles?
@@jeffreysantos9070
13,342.08
@@jeffreysantos9070 she has 254k and rising
@@MrDietring wow!!
@@dalehall2993 FU Dale
Hey! Your videos have helped me many times. I'm happy to help you this time. Turns out the answer is, there's a specialized procedure for bleeding breaks on that particular model. What you have to do is push the brake pedal down once, open up the rear nipple and bleed. Then you have to wait 15 full seconds. Then you put down the brake pedal just once and bleed. On most cars you pump the brake pedal a bunch of times. On those models, your partner has to push the brake pedal to the floor only once. Then you open it up in the rear. We did everything, bled the hell out of the brakes the normal way, but when we followed this procedure we still got black fluid out and lots of bubbles. Completely changed the way the pedal felt. They also want you to bleed the reservoir. They want you to do that by having your partner put their foot down on the brake pedal, and you slightly open the forward most brake line on the brake reservoir. You do that a few times, then you follow the same procedure for the backmost brake line on the brake reservoir. That's your starting point. After that, bleed the rear brakes. But you absolutely have to wait 15 seconds in between! And you cannot pump the brake pedal. It makes it almost impossible to bleed. Have your partner push it down once, hold, flush the back end, close it back up and have your partner release the brake pedal and wait 15 full seconds. Then try again.
I have the same problem , an spongy pedal en poor rear brakes. The problem (and the dashboard warning light is shining) since i changed the brake dot 3 oil after there was to little oil in the reservoir. I will try out your advice !
@@marcvermeylen4891 did it work?
The NBS Silverado master swap makes a BIG difference in pedal feel on the older trucks. I did this swap on my Tahoe and it was night and day difference. All you need is a master from a 01 and up and an adapter fitting and you get better pedal feel. I later upgraded to the 13 inch 05 up front rotors and calipers since my truck is 4wd, huge increase in braking ability.
The 1990 has the RWAL (rear wheel antilock) system. It's that other module next to the proportioning valve on the bracket next to the master cylinder. Pumb the rear brake line directly to the proportioning valve bypassing the RWAL module. The modules are known to cause a spongy brake feel. My 1990 had this issue and that was the fix. Mine has great pedal feel now.
Eric I appreciate and enjoy your videos. I know you went to a tech or trade school which is far better than shade tree shops.
I have been in the trade for well over fifty years; and many authorized Factory approved schools which includes GM Bendix Westinghouse brakes school (air&hydraulic), Cat, Cummins and Detroit Diesel.
Well my point is when working on hydraulic brakes I was taught when replacing a wheel cylinder you also replace the apposing cylinder and you gravity or preferably pressure bleed as pumping the brake pedal can create micro bubbles in the fluid; which causes soft/spongy pedal. And the micro bubbles really became a problem after the invention of disc brakes!!!
To start off I would have to say, what a great sense of humor!
I thought several of the GM products had an "anti-reverse" valve that doesn't allow you to "pump" the breaks for bleeding. When pumping the breaks, this valve engages and stops the bleeding process. The brake pedal feels harder (until the engine is started), but the air in the lines is never displaced. Not sure on your rig, I have found it on some products.
Thanks for taking the time to make the video.
I was having the same issue and thought about doing the same with my suburban, I changed the front ABS sensors instead and it fixed the problem. Brake pedal is way more responsive to what it was before. I would definitely recommend it Eric!
Cool. You could replace the rubber brake lines that run down to the calipers with braided stainless. This helps get the brake pedal feel back. Those old rubber ones start to stretch alot over time.
Delete the ABS module and it's control module. That solves the spongy brake problem on these trucks. Ran into same problem on mine when I changed the rear wheel cylinders. The old ABS on these trucks are not the best and you cannot bleed the AND without a GM original diagnostic computer scan tool.
Most bi-directional scan tool allow for abs cycling and finding snowy,slippery,or dirt road to stomp the brakes works in a pinch.
My buddy’s 03 blazer is doing the same thing. New MC, bench bled, all 4 wheels bled like crazy, still a soft pedal. Although with the vehicle not running you can pump them up and the pedal is rock hard. I’m still leaning towards air in the ABS module.
@@ImTheJoker4u yep, this happened to me on my '88 GMC ,will try !
Absolutely delete RWAL ABS. Cause of serious problems and can actually leave you with no brakes whatsoever. At least disconnect the dump valve solenoid. Brake warning light can be ignored if necessary. By the way if your brake warning light comes on consistently at around 35 mph that usually indicates brake pedal switch needs replacement. May otherwise function properly but has to do with the way it communicates with the electronic module. I know, sounds ridiculous, and it is. RWAL ABS was not good.
Anyway to upgrade instead of delete rwal?
And a new brake master cylinder didnt work...
Eric, I appreciate your straight forward 100% honesty...b/c I know I'm going to spend money on a new MC and still get a spongy feel.
But, you know what I think it is??...if you installed a new brake caliper piston seal it may not 100% seal the old brake caliper b/c a 30 year old caliper changes shape as they age ...
I have a 96 K1500 GMC Yukon, same problem. I did the 99 master cylinder swap, like everyone said to do. Didn't do a damn thing except make my bank account smaller in dollars. I have been told by two GM Line mechanics, that I have to blead the Kelsey Hayes ABS computer. Problem is the only way to do this, is with a OBDII device that has the function built in. To get one that does you have to spend more than I want to. Solution take it to a shop and they will do it for just under what he OBDII device costs. Oh well, the price we pay for rebuilding old Chevy's and GMC's. I love the 94 to 98 Chevy Silverado K15 & 2500 and the GMC counter parts. I have had five of them and have amassed quite a parts store, and learned way more than I should have about how to maintain and service all of them. From replacing engines, Tyranny's, Transfer cases, lifting, and all kinds of customization.
Hey Ericthecarguy
I have been in a problem with a 94 Chevy 1500, with a spongy brake pedal, I ended replacing the rear drums and that solve my problem !!!!
Often the rear brake adjustment can solve a soft pedal. However, as mentioned at the beginning of the video, I did that before trying the master cylinder. Glad it worked out for you though.
Why did you have to replace the rear drums to begin with? Were they worn excessively? If they were wouldn't your self adjusters move the brakes shoes closer to the drum surface?
Per usual, very informative and thorough. So well, I feel confident enough to do this on my car. Thanks again, Eric!
Excellent video. The easy way to fix a brake issue. Easy step by step instructions on this to keep from having issues later with the brakes , great video. Thanks
Excellent explanation throughout the process. Only thing I would say is "OK hold it" does not mean to stop pumping in whatever position the foot is in. It means hold the foot down with pressure and do not release the pressure on the pedal even when the pedal drops.
Yes hold the pedal to the floor until told to release
You got it ETCG. The 88-98 trucks had the “spongy” brake pedal throughout the model years, and all models had it. Alot of guys swap the master cylinder (and brake booster for some) from 99-06 NBS trucks which helps get a firmer pedal. Others ditch the factory ABS and get a proper proportioning valve to help with it as well.
Aside that, I am glad to see you are doing videos on the GMT400! Oh, and I had to check to make sure Cameraman Derek didn’t take my shoes... I have the exact same pair. Haha!
That's exactly what I heard. I'm thinking of making another video installing those parts. If that doesn't work, I was going to go with steel braided brake lines. Thanks for the info.
Yup every chevy ive owned in that era always seem like it never had as good as brakes as it could of compared all other vehicles ive owned
rrcoster I am not too sure. I have driven a few GMT400 trucks, including my current daily driver which is a 98 K1500, and it has done that on all. I have just gotten used to it, I suppose, and can still activate an emergency braking procedure without locking up the wheels (ABS quit working a while back). That being said, I have also driven some GMT800s (99-06 models) and felt that the brakes had the same/somewhat similar feel. Perhaps the 800s were just a tad firmer, but otherwise. Alot of 400 owners that have done the 800 MC Conversion claim to have a better, firmer pedal. I’d like to feel one to see if it is better after all. I hope that if ETCG decides to do this to his 90 Chevy, that he will share with us the findings and conclude if it is better. I wonder if MCs from 07-18 work better too. I also wonder if it is better to get rid of the ABS modules and put the proper proportioning valve and converting the rear to Disc if it would help. All this is just reaching for straws, I suppose.
Chris Jacobs I am sure those do make a difference. I am not real sure why people make a big stink about it, as I have driven a GMT400 for a while, and it has always had this problem. I don’t even consider it a problem. The ABS doesnt work, yet I know how much pedal to give it especially if I need to stop on a dime. At the same time, I havent driven a GMT400 with the conversion done, so I can’t speak for it. I can only go on word of mouth. I guess it all depends on the driver, after all.
In any case, steel braided lines may help, and I eventually plan to do that with mine. I am not in a rust belt, so my lines are in great condition. Thanks for the tip! ETCG, you may want to try this first!
I've worked on a fleet of Chevy trucks from 1986 to 2002 model years and they all had spongy pedals since they were new. I experienced the same thing on a first gen Toyota Sienna, which I hated.
On my 2005 GMC Sierra, I had nearly zero braking from a worn wheel hub (bearing) so the ABS speed sensor was "confused". I isolated the problem by pulling the ABS/Brake fuse and brakes were perfect in manual mode. There are so many damn possibilities on modern vehicles. Sometimes I just want to buy an old truck from the 1950's, dammit.
Exactly Gy Bx. Also the hi-tech crap on the new stuff just creates more of headache tryin to diagnose a simple problem.
My dream car is a 1963 Chevy Nova 6 cyl 3 speed manual transmission - where the only thing electronic is the radio. These cars ran forever and were cheap /easy to maintain.
😄
Watched the vid last night to prepare to replace my sons MC on his S10, did the swap no problem! Thanks a ton!!!
Wow, a lottta good tips and ideas but I feel like some people in the comments dont realize that you are a career mechanic and do this for a living. Great video on how to replace the master cylinder and I'm surprised that you didn't get a bunch of you have to bleed brakes this way comments
Adjust the rear out all you can, I have had a ton of what seemed to be spongy brakes on GM Trucks that cranking out the rear shoes solved.
what does adjusting and cranking out mean? Do you mean bleed it a lot or?
@@jestes7 Turning the adjusters out, minimizing shoe travel.
@@routeoneauto wow fast response, thanks!
G'day, Eric! Yes! I second that! "Eric O., would be very proud!!" Thank you for "how to replace, and bleed a master cylinder on a C1500, 1990 5.7L!!"
Cheers! :D😊🚚❤️
Since I'm reviewing some of these older videos - I felt it only right to comment. Thanks again Eric!
I've got a 1991 C1500 350tbi and I've always had a great pedal... Never any sponginess, or fade. One thing I did do though was install a set of braided stainless steel lines and that made my pedal rock solid... noticed it for sure!
I was thinking of that too. Thanks for the recommendation.
Great Video Eric. This will help a lot of people.
We're getting bloopers now? love it!
I had a Caprice 9C1 that had a spongy brake pedal. Switched out the rubber brake hoses to braided stainless ones. Helped significantly.
I couldn't get air out the system for months.So I put the heavy duty master cylinder.Bench bled and bleed all four wheels.Brakes work perfect.
If that truck has rear ABS, there is a dump valve that gets triggered and air gets caught in or if the rear brakes were ever depleted of brake fluid from a rusted brake line or blown wheel cylinders. May times I thought I had a bad master cylinder when all it needed was a bench bleed. It always works and the brake pedal will be awesome on it Apparently you can also crack a line off the rear ABS valve and open and close it like a bleeder as if it was at a brake. Oh I see now yours has a bleeder at the rear ABS. My later model does not. Mine stops fine. Stock master, I keep the rear drums adjusted fairly tight and run performance front brake pads. Used some new ACD brake shoes too, they have alot of bite compared to these cheap ones I have. basically if you have a air pocket in that rear ABS solenoid/ dump valve the pedal is going to suck no matter what you do. Sometimes mine gets spongy all of a sudden but firms up. One day I am going to delete the rear ABS. All it needs is a few short brake lines made up to patch it in. www.aa1car.com/library/abs_kelseyhayes_rwal.htm
+Ghetto Wagon - Good Link! 😅 😅 😅 😅
Great info my 99 pedal is spongy and I will by pass the abs.
i put new front rubber lines on my 94 gmc and that made a real difference hope this helps and they got the nice stainless steel lines for these at orilles for like $85 for all 3 lines also i had sponge brake on a 96 jeep gc and i took off the abs relay and it was much better i have yet to lock the brakes up at all
..what is "orilles"?...O'Reilly's, maybe?.. :)
Check the brake booster push for clearance. There is a very specific clearance for the push rod for each model. Hope that helps.
I read somewhere a long time ago that spongy pedal feel is usually the brake booster diaphragm leaking and giving out. As already concluded, you changed the master cylinder and the only other part that could be problematic is the booster. Great vid as always and thanks for sharing
Dude! You have an Amsoil fender cover! Go Eric!
Yeee Haw... been waiting for you to start up videos on this truck...! Awesome Eric!
Interesting, Eric. But there is another possibility , air in the ABS HCU. With some vehicles, the hcu has to be run with the scantool to push air out of the unit, then the rest of the system has to be bled. If the hcu is not actuated, it is very difficult to bleed the air out of the system. In your case, your truck has an RWAL system. Also, my brake bleeding sequence preference is to look up the sequence and do it that way. For those who are not aware; usually the sequence starts with the corner farthest from the master, brake line wise. It is because of how the lines are run. For example, the lines on my 95 Neon run from the master to the firewall, travel along the firewall to the right side of the car, then run down under the car, and run to the rear on the right side. That makes the left rear the longest line on the car, and the furthest from the master. The bleeding sequence starts with the left rear, then to right front, then to right rear, then finally the left front.
I have a 1994 Chevy C1500 and have the exact brake issue you have Eric. I know others that have the same issue as well. One guy had a brake shop tell him that is just the nature of these trucks. I also saw on TH-cam someone say the problem is the rear brake anti lock is causing the spongy brake and bypassing this but rerouting a brake line fixes the problem but I haven’t tried that yet.
I heard the hissing sound when derik was pushing on the brake pedal and knew it wasn't fixed. Either brake booster or leaking vacuum line, sometimes the foam if you have it is degraded and you will hear the hissing.Glad your back missed your knowledge of cars brother. Oh nice can for spraying brake cleaner, just put some air in it and spray away.
That's not the issue, it's just how some systems sound. If the booster was bad, the brake pedal would be extremely hard because there would be no assist. I'm thinking of getting the new parts and trying it out to see if that solves the problem.
This is awesome Eric! Btw a 1990? Nice! I hope I can keep my vehicles going as they get older too. Thanks for the knowledge!
..I don't consider a 1990 truck that old..now my '70 Chevy, yes, somewhat..the '52 Dodge in my dad's shed?..yes....
I have had success with eliminating the the “spongy petal” by only pushing the piston into the master 1/4 to 3/8 of an inch. This with also not putting the petal to the floor just pumping it 3” approx and holding it. This was a “fix” from an instructor that observed the the length of movement of the plunger on a Raybestos bleader bench...
Hey Eric i saw your video and im sorry to hear about your troubles. If your truck has ABS air can get trapped in the ABS module. There is actually a "brake bleed" function that bleeds the abs module using a scan tool. I use an Autel DS808 but im sure there are other scanners capable of this function. If you can borrow one from someone give it a try. I had the same issue on a 99 suburban and it worked for me.
Hold the phone on any brake modifications you do!!!
I have a '98 that I'm LS swapping. I'm installing a Wilwood 1" master cylinder, ABS delete, and a Little Shop MFG rear disc conversion.
I'll let you know how it goes.
If you don't like the pedal feel, I think I know what you mean. When you first slam the brake as hard as you can, the system doesn't build pressure to stop the vehicle. Slower application of the pedal works just fine.
On modern trucks, they're waaay over-boosted so the pedal is super mushy. I know the feel you're going for. "You like it when you can push the pedal as hard as you can, but without the pedal going closer to the floor. You want to feel like you're standing on top of a spinning smoothly machined iron disc. You want to be able to feel if your rotors are warped by how they modulate the pedal."
Yes, Eric O would be proud. Nice one.
Excessive amounts of brake clean being used brings a little tear to my eye :')
Using enough of it brings a tear to everyone's eyes!
Brake Clean also makes great nasal decongestant. Just ask Eric O
Brake clean.. on brakes... what the hell?
Lol, yes, especially - - INHALING IT! as well....
Bleed the abs module directly under the master cylinder. My 89 has that old school rwal (kelsey hayes I believe), which can still have air even after a full bleed on the rest of the system. Kept looking at it on your video, the little bleeder there (just above the yellow paint mark).
Replace the old rubber brake lines is a big help
Shout out to SMA!
10:38 that sounds like progless lmao great video
Add shims to the pushrod between the rod and the plastic sleeve; worked for me.
Love seeing the 90 Chevy under the knife. I have one myself. Thank you Eric
Awaiting the booster video. I see what you did there... Keeping suspense!
i thought this video 3 or 4 years old but then i realized it is very new
Eric O. would be jealous of your brake clean sprayer!
Great video Eric. It’s very informative. I just had my brakes become soft the other day on my 91 C1500 after having to brake hard to avoid an accident. A friend helped me bleed the brakes which did not fix it. He suggested exactly what you did at the end of your video so that’s my next step.
Why contaminate with silicone when a little dot 3/4 works great?
Not really gonna do anything
my thoughts exactly lube all seals with clean brake fluid when ever working on brake systems
I remember back in the late “60s” when I was learning the trade, I left a”drop” of brake fluid on the fender of a black hearse. Later when I went back to wipe off the fluid, it left a bright shiny bare metal spot on the fender where the fluid sat.🤭
Another great video! I vote you make it into a performance truck.
I never bench bleed master cylinders. I put a vacuum on the reservoir, take it off and refill. Do that a couple times then put a vacuum on while pumping pedal and that usually gets all the air out. Many car manufacturers vacuum bleed the brake systems on the assembly lines. No mess and a little faster.
Good timing. My 2000 Buick LeSabre had this issue (no brakes, dry lines) and swapping master cylinders also fixed it. That said, I didn't bleed the wheels after, so maybe I screwed up there (or I missed a leak, it's a real rust bucket).
I should've hung onto my '94 K1500. Biggest mistake I ever made was selling it, and buying an '07 Silverado 1500. The '94 was 100x more reliable! With that in mind, I'd keep that one stock, and just drive it until the body falls off. I sold my '94 with 266k miles, and was STILL running like a top! Also had a more quiet interior than my brand new truck did. OE u-joints made it 222k miles. May not have had much top end power, or a very good ride, but at least it didn't cost me an arm and a leg to keep it going ... after spending an arm and a leg for it, like the Silverado! GM ain't what she used to be, that's for sure. :(
Anyway - great vid! Gotta run - time to refill my IV bag with brake clean ... 😁
94-98 was the best years to buy because GM was working hard to compete with the Toyota trucks coming into the market. Some of the best trucks ever made.
It certainly shows! My '94 was bulletproof, while my '07 has been the biggest, most expensive disappointment of my life.
Once a car or truck is out of warranty they never have squeaks or rattles.
may daily work van is a 92 astro..i will never sell it..most reliable vehicle i have ever owned and i work her every day...easy to diagnose and fix..those old chevys only had like 5 sensors that could go bad lol
Remember that Astro is equipped with a fuel pump that is guaranteed to fail. I also like the Astro (but the last model only) I am not a fan of TBI and the last model came with the 4.3 and multi port injection. I made a good bit of money working on Astro vans (Chevrolet Dealer in Tucson AZ) My area was light line, AC, electrical and interior trim, rounded out by new car accessories. Not everything in the garage is heavy line, brakes,oil changes. Some shops continue to force mechanics to be "bumper to bumper" mechanics. This is a policy I will not work under. I just do not hire on with firms that require bumper to bumper work.
I have a 1995 suburban that gets that spongy feel too. Once in a while, if I hit the brakes hard enough while backing up, or have adjusted the rear shoes myself, the brakes get really good and she'll stop on a dime. I've done water crossings a few times as well with it, and then the brakes REALLY work for a while afterwards (until they fully dry back out anyways). I subscribed just to see if you do that brake upgrade to the gmt800 stuff, and i really like the clarity with which you present yourself.
For the cost of brake fluid, I do a complete flush whenever I change calipers/cylinders or buy a used vehicle. A lot of people don't realize that brake fluid is actually a consumable that needs to be replaced due to water absorption. I have a little one man brake bleeder that I use for the work. (essentially a jar with a hose that goes to the bottom of said jar that ensures air isn't sucked back in when releasing the pedal. Mine is a little plastic deal with a magnet so that I can place it higher than the bleed screw.)
Good video... I was taught when bleeding breaks to always start at the brake that is the furthest away from the master cylinder, then the next furthest and so on.
Thats the correct way.
I like how at the end of the video, you admit that it didn't solve your problem.
Imagine someone following your video instructions and ending up with the same results 🤣🤣🤣
81 c10 has a firm pedal.
Must be combination of the master cylinder design and the size of the booster.
Always wondered why some newer cars you barely touch the pedal and it grabs.. then others are softer.
I did the exact same thing to my truck 6 months ago and got the exact same result.
You might not be driving it enough to realize, but another common thing is for the truck to be a little late on releasing the Driver's side brake disk, or not completely release at all. Check it out next time if you've got time. I never found a fix for this problem either, and I've replaced everything short of the brake lines.
If you replace the 1/4" rear steel brake line with a 3/16" you will get much better pedal feel from a 88-98 chevy truck
leeding practice as taught early on: furthest to closest bleed point.
Yep, start at furthest from the ABS/Proportionality Valve, Right Rear, Left Rear, Right Front, Left Front...
That truck looks fantastic!
I had an 88 Chevy regular cab, short step side pickup. 350 V-8. I drove that truck everyday for 11 years. Kept it in top mechanical condition. Then I got a suer dear on a 95 Dodge ram 2500 with the cummins 12 valve. Ended up selling the chevy and eventually sold thr dodge, now drive a 98 dodge ram1500 with a 318...good truck, only had it a bit over 7 years. I kick myself everyday for ever selling the littli 88 chevy. It was the best truck I ever owned.....oh well, they say hind sight is 20/20.....
I figured it out......was going to replace my master cylinder from AutoZone with a warranty replacement
.......glad they didn't have it ,in stock.....went orieley auto parts,bought a 100 persent new master cylinder.....now have firm peddle ,not spongy foot pressure.i figured new would have firm new inner springs.
Great video...especially like when mechanics mention bolt/wrench sizes in their videos!
I had the exact same issue with my 90 1500 Suburban. I watched one of you earlier videos on master cylinder bleeding and was ready to make it happen. The instructions that came with my new master cylinder told me to leave the plugs in and gently press the plunger until it stopped bubbling. After bleeding all the lines, it all worked out fine and the peddle no longer sinks to floor at a red light. Like some others have said in the comments, the brakes still aren't as firm as they should be.
Do the late model master cylinder swap he talked about. I did on my 96 Express. I got it off of a 2002 Suburban. It's unbelievable the difference it makes in pedal feel.
Maybe consider replacing the old rubber brake lines. They degrade over time and tend to balloon outward instead of directing the pressure toward the brake pistons.
When $$ comes available I'll look into that.
Yep, they're nearly 30 years old.
Seriously, brake lines can be an issue, but if you have that 80's style square capped master cylinder, they are known for spongy pedal feel. I'm willing to bet once you replace all the brake lines, you'll still have the crappy pedal. It's just a design flaw that was fixed on later models with the newer style master cylinder
i've had to do more master cylinders on chevy trucks than i even want to think about.....a little trick i have done to get the air out of the lines is,i will take a front and rear wheel off,and have someone push the caliper piston back in with a c clamp while i loosen the line at the master cylinder. i do bench bleed the master with brass fitings and clear tubing before hand.
I have the same truck. There are four things you can do on these trucks for better brake feel, in order from bargain to bankrupt.
1: ABS delete.
2: Rear disc conversion.
3: 1" master cylinder.
4: Use a rear disc conversion with a 2" D154 caliper and all of the aforementioned mods.
4.5: Front caliper mod. Replace the front pistons with stainless cylinders that don't have notches cut in them.
Why didn't I get a notification about this video? I stumbled across it...ugh youtube
The mech a nic Same here, and I follow Eric very closely!
Same!! I have even clicked the bell and didnt get a notification.
The bell has to have those two "thingies" over it. It will say at the bottom left of the page "You will get all the notifications". Otherwise it would say "You will get notifications from time to time" and that's probably what you have set it to.
I have a. Stripped hole connecting brake pads line
Sucks it didn't solve your problem, but atleast you know it's functioning properly.
The ABS units tend to be a problem on these. I had removed mine on my 1994 GMC Safri AWD. They wanted $300 bucks to replace it. Nuts! But it made a world of difference
Nice job..excellent video. Happy I watched your video. Had I not viewed your video I would of had a world of trouble because I would of not benched bleed out the master cylinder .