You just answered a question that has plaqued me for over 25 years. My first car had no rear brakes. No matter what I changed or how much money I spent I couldn't get rear breaks. 25 years later and your like heres your problem. Thanks for the video. Ill carry this knowledge with me for the rest of my life.
I got just front brakes. Was told it was the booster but I also was told the proportioning valve could be the problem. I think imma start with the valve then work towards the more expensive parts
Wow, there are brains out there. I was doing that last night for 3 1/2 hours trying to figure out why I can’t believe my brakes. I gave you five thumbs up.❤
That front "button" is actually the stem of the front metering valve, and is not connected to the shuttle valve. Pressing it will not recenter the shuttle valve. It needs somewhere to go when you press the breaks, and extends outside of the valve body as it opens. The rubber cap just prevents dirt from scoring the stem, and possibly causing a leak. The method to recenter the shuttle valve is to crack the break line open on the opposite side of the original failure. Then have someone use moderate pedal preasure, and hold while you retighten the break line. It's best to remove the light switch first so it doesn't provide any drag on the shuttle valve while recentering it. Then insert the shuttle valve blocking tool, and bleed your breaks. If it won't recenter it's usually because the o-rings on the shuttle valve have hardened. Which causes it to stick. You can try replacing them, but make sure it's a rubber that doesn't break down in break fluid. The shuttle valve can be removed by removing the front metering valve and the read orafice of the proportion valve. The a small brass pin punch can pass through the front metering orafice to knock the shuttle valve out the back of the valve body. If the cup Seals are bad (break fluid will be come out when you remove the warning light switch), I have not been able to find a place to buy them. Which means you are stuck buying a whole new valve. A PV2 type valve will work for most GM break systems. Just make sure you get the correct disk/disk or disk/drum version to match your setup. Hope this helps anyone having difficulty with thier combo valve.
William Adam.....you just solved me a problem ! I've been going crazy for 3 days, I read your comment, and there was my answer, don't know how I missed this, "cup seal". , I'm 75yr old retired mechanic and this one went right over my head😅 thank you sir
@@larrydriemel6242 lol. Something I learned as a computer tech was, that sometimes a fresh pair of eyes are needed. Eveb if they less experienced. I would be struggling trying to troubleshoot an odd server problem. 5 hours later I would have one my guys who wasn't as good at troubleshooting, but was a hard worker look at it. Less then 2 minutes later he would have the problem pin pointed. It's frustrating at times, but it works. 😂 I learned a lot about the combo valves when I converted my 1968 F100 to front disk brakes. I wasn't comfortable doing it until I knew how they worked so I chose the correct one. So I set out reading every technical document I could on them. An old habit from tech days. Cup seal was the best way I could describe it. I can't recall the technical term for them.
I just bought a new PV2 for disk/drum, removed the switch to insert to the stop, and I’m concerned the shuttle valve isn’t centered because I see brass that’s about 3/4 of the way filling the void, the gap facing the rubber cap/front side. Is there a way to verify the new prop valve was shipped in it’s centered neutral position, as I don’t want to spend all the time to install, try to bleed, etc, just to removed it to re-set it
@@WesternReloader yes. If you put the holding tool in and it seats without issue, it's centered. Basically the way it works is that the center portion of brass shuttle is narrowed. This allows the plunger in the warning switch to extended and open. There's a ramped section to either side of the narrowed center section that pushes the plunger contact closed when one side loses pressure. This grounds the warning light turning it on. If the holding tool can not be screwed in, the shuttle is not centered. BTW no need to crank down on the holding tool. Snug is enough. The solid pin can not be pushed out of the way like the plunger of the warning light can be. This is what keeps the shuttle from moving. Not how tight it is.
You're the first video I watched that I can understand. I got a 88 Chevy Silverado and was driving me nuts. Thumbs up thanks a lot for the information. 👍💯🐟👋👋👋👋👋👋😁😁😁😁😁😁
Thanks for posting this video and taking the time to explain the functions. Exactly what I'm going through, BUT I purchased a master cyl thinking..... ya know the deal! cheers!
Best video explain I've witness since looking.... Thanks man....I have a 94 GMC K1500 doing the same thing... Pedal feels spongy.... The valve leaks at the light switch... I know the rear drums are shot so ordered new drums and valve... Sure its really out of adjusted on rear drums....
wow so informative i just converted my rear drum to disc brakes and i just couldn’t get pressure to my rear brakes i was everywhere on forums and went through 3 mechanics who couldn’t find the problem i am hoping this is the problem so i can drive my truck again thank you 🙏
Man thanx, been breaking my head against the wall.. Changed everything on front and rear brakes. And stil having problems after " bleeding the system, but never touched proportioning valve.
Good to know. We deal with a lot of break bleeding and have run into this issue a lot. Won't be buying those $50.00+ proportioning valves so much now. Thanks
The pin in my sensor is pushed in an won’t come out. The part is discontinued. Having trouble finding it at the salvage yard. It’s for a 2004 Avalanche. Any help would be greatly appreciated
Those ports can become clogged with sediment if you push the caliper pistons back to put on new pads. Some thing with drum brakes, if you push the wheel cylinders back to allow space for the new shoes, you can push sediment back up and into the proportioning valve which can then clog a port or two ports or all the ports. If that happens, the valve can go off center. A leak can cause the valve piston to go off center as well. The switch mounts on the proportioning valve where there is no fluid. It should be dry in that spot. If not the valve is leaking.
Pulling my hair out! Have an aluminum screw in blocker tool like you mentioned. Can't see the sensor port to check if valve is centered, because of location, but aluminum pin tool screws in the whole way and seems to bottom out. I hate to tear apart the passenger side header downpipe to get to it and all the brake lines connected to the proportioning valve. But what you say makes a lot of sense. And if that tool is not screwed in even 1 or 2 threads more than i can see, then that may be my issue! I'm only going by feel right now and it feels like it is bottoming out but You can see. I may have to start completely over it with this valve.
Question, when the low brake fluid sensor is removed, is there supposed to be any pressure or brake fluid in that chamber? I just did a proportion valve rebuild for an 84 Mustang. Different animal, but same function as the proportion valve requires a set screw to hold the internal piston from moving while bleeding brakes. But after my rebuild, my low fluid switch is leaking brake fluid through the top pins. Not the threads. Does that indicate the rebuild wasn't a success? Right now I have the set screw acting as a plug because I cant used the stock low fluid switch. It's possible that when the torched the lines to get them free, they damaged the plastic sensor, but just the same, I was under the impression there wasn't supposed to be fluid under the switch in the chamber where the sensors prong rests in the V groove.
My rear brake line broke and it was fixed and they bleed the brakes...but the light still there..They told me to buy a new valve...If it push that pin with a tester would it reset?
Do you have to have the valve off the truck to move the shuttle valve? Or can you move it with it completely mounted? Can’t seem to get mine to move back to center
Oh my frickin... THANK YOU! Can I just put a brass plug in the brake light switch spot since I have different gauges and don't have stock warning lights?
Yup. The warning light switch is not needed for operation. Just make sure the plug does not extend past the internal threads. This way the combo valve still functions as designed.
Combination valve with proportioning valve and a fluid pressure differential valve. Which is the shut off valve. Should also trip a light. The proportioning valve keeps rear wheels from locking up during hard braking.
Here’s some more good info in these magical mystery devices- use a brass one if you can (S-10’s use them), the stock cast iron ones corrode and get gunked up. If you have it off, you can hold it upright and tap it on a hard surface and that should move the valve - if it doesn’t, it’s gunked up inside. Also that switch is your friend, it’ll tell you when something is wrong or if there is air in the system…I don’t know why you’d make in inoperative! Plus you want that shuttle valve to move, if there was ever a leak.
If you have repaired the leak you want to open the opposite side slightly while someone press the break pedal, and then close it off. If it's stuck, yes removing the valve and using compressed air can sometimes knock it loose. Then double check the orings, and center it before reassembly. Sometimes when they are stuck it's because the orings are toast, and have adhered to the bore surface. So if it's stuck it's just a good idea to replace the orings.
I have recently found that it is utterly impossible to find that switch for the proportioning valve for a 2004 Yukon, not even the dealerships can get it. Insane
Yeah man the them can be a pain to reset once they move! I see that new Hayes Street strip Clutch pressure plate! We need a one around on the bad 55 machine man! Been a while since ive seen it! Have a good one ✌️
If you, JB Weld that valve switch, you will disable the ability for your valve to move if you lose brakes on either the front or rear meaning the pin won’t move upward FYI
Yup. Couple of possibilities. First inspect your setup to make sure it is still stock, and hasn't been "modified" by a previous owner. If it has, or there are missing comments, decide if you want to replace or upgrade to front disks. If go the upgrade route, don't use an adjustable propotiining valve if you plan on it beibg a steet car. Use a disk\drum combo valve, or a disk\disk combo valve if going with a 4 wheel disk setup. Adjustable propotioning valves are good for the race, but suck on the street. Then I would suspect either bad wheel cylinders that don't retract, or a bad combo valve that is allowing full line pressure to build in the rears.
Close the rear bleeder open the front bleeder and smash the brake pedal to the floor three times did the brake light go out or flicker if yes close the front bleeder and open the rear bleeder and let it gravity bleed until solid fluid comes out of all bleeders
You either need a new one, or if yours uses standard orings. Just disassemble, clean it, and put in new orings. Basically your orings gave hardened, and developed a flat surface. This allows break fluid to enter ware it shouldn't be. Some older combo valves that use cup seals at either end still have rebuild kits that come with new cup seals. Hope this helps.
You just answered a question that has plaqued me for over 25 years. My first car had no rear brakes. No matter what I changed or how much money I spent I couldn't get rear breaks. 25 years later and your like heres your problem. Thanks for the video. Ill carry this knowledge with me for the rest of my life.
25 years! I would have went to school just to learn hydraulic components if it took me that long. Haha
I got just front brakes. Was told it was the booster but I also was told the proportioning valve could be the problem. I think imma start with the valve then work towards the more expensive parts
Wow, there are brains out there. I was doing that last night for 3 1/2 hours trying to figure out why I can’t believe my brakes. I gave you five thumbs up.❤
Testing it for ground to see if it is tripped was golden!
That front "button" is actually the stem of the front metering valve, and is not connected to the shuttle valve. Pressing it will not recenter the shuttle valve. It needs somewhere to go when you press the breaks, and extends outside of the valve body as it opens. The rubber cap just prevents dirt from scoring the stem, and possibly causing a leak.
The method to recenter the shuttle valve is to crack the break line open on the opposite side of the original failure. Then have someone use moderate pedal preasure, and hold while you retighten the break line. It's best to remove the light switch first so it doesn't provide any drag on the shuttle valve while recentering it. Then insert the shuttle valve blocking tool, and bleed your breaks.
If it won't recenter it's usually because the o-rings on the shuttle valve have hardened. Which causes it to stick. You can try replacing them, but make sure it's a rubber that doesn't break down in break fluid. The shuttle valve can be removed by removing the front metering valve and the read orafice of the proportion valve. The a small brass pin punch can pass through the front metering orafice to knock the shuttle valve out the back of the valve body.
If the cup Seals are bad (break fluid will be come out when you remove the warning light switch), I have not been able to find a place to buy them. Which means you are stuck buying a whole new valve. A PV2 type valve will work for most GM break systems. Just make sure you get the correct disk/disk or disk/drum version to match your setup.
Hope this helps anyone having difficulty with thier combo valve.
William Adam.....you just solved me a problem ! I've been going crazy for 3 days, I read your comment, and there was my answer, don't know how I missed this, "cup seal".
, I'm 75yr old retired mechanic and this one went right over my head😅 thank you sir
@@larrydriemel6242 lol. Something I learned as a computer tech was, that sometimes a fresh pair of eyes are needed. Eveb if they less experienced. I would be struggling trying to troubleshoot an odd server problem. 5 hours later I would have one my guys who wasn't as good at troubleshooting, but was a hard worker look at it. Less then 2 minutes later he would have the problem pin pointed. It's frustrating at times, but it works. 😂 I learned a lot about the combo valves when I converted my 1968 F100 to front disk brakes. I wasn't comfortable doing it until I knew how they worked so I chose the correct one. So I set out reading every technical document I could on them. An old habit from tech days. Cup seal was the best way I could describe it. I can't recall the technical term for them.
I just bought a new PV2 for disk/drum, removed the switch to insert to the stop, and I’m concerned the shuttle valve isn’t centered because I see brass that’s about 3/4 of the way filling the void, the gap facing the rubber cap/front side. Is there a way to verify the new prop valve was shipped in it’s centered neutral position, as I don’t want to spend all the time to install, try to bleed, etc, just to removed it to re-set it
@@WesternReloader yes. If you put the holding tool in and it seats without issue, it's centered. Basically the way it works is that the center portion of brass shuttle is narrowed. This allows the plunger in the warning switch to extended and open. There's a ramped section to either side of the narrowed center section that pushes the plunger contact closed when one side loses pressure. This grounds the warning light turning it on. If the holding tool can not be screwed in, the shuttle is not centered. BTW no need to crank down on the holding tool. Snug is enough. The solid pin can not be pushed out of the way like the plunger of the warning light can be. This is what keeps the shuttle from moving. Not how tight it is.
1000 times "like"! I have '88 Trans Am GTA and I have been trying to reset for a year now! Thank you!
Thank you. I haven’t had rear brakes for the last 4 years 😂😂😂😂
You're the first video I watched that I can understand. I got a 88 Chevy Silverado and was driving me nuts. Thumbs up thanks a lot for the information. 👍💯🐟👋👋👋👋👋👋😁😁😁😁😁😁
Great info! I never knew this in all the years of messing with old GM stuff!
Thanks for posting this video and taking the time to explain the functions. Exactly what I'm going through, BUT I purchased a master cyl thinking..... ya know the deal! cheers!
Best video explain I've witness since looking.... Thanks man....I have a 94 GMC K1500 doing the same thing... Pedal feels spongy.... The valve leaks at the light switch... I know the rear drums are shot so ordered new drums and valve... Sure its really out of adjusted on rear drums....
Pat your self on the back your sharing awesome info bro
wow so informative i just converted my rear drum to disc brakes and i just couldn’t get pressure to my rear brakes i was everywhere on forums and went through 3 mechanics who couldn’t find the problem i am hoping this is the problem so i can drive my truck again thank you 🙏
Did you solve your problem and if you did what did you have to do
Brother it is very valuable, and thank You for sharing. You're a big help.
Omg thank you...yes i have been pulling my hair out..now that almost bald i think i know what to do now..thanx buddy
Man thanx, been breaking my head against the wall..
Changed everything on front and rear brakes. And stil having problems after " bleeding the system, but never touched proportioning valve.
I have a 68 Chrysler Newport with a rear break leak i repaired, and this is my problem solved. Thanks
Man I just went through the heart ache, I ordered a tool and another proportioning valve. Thanks.
That kind of thing can drive you nuts, thanks for sharing, that’s a great tip. 👍🏻
Thank you for the tip I have in 1977 El Dorado Barrett that was my problem with the front brakes
Good to know. We deal with a lot of break bleeding and have run into this issue a lot. Won't be buying those $50.00+ proportioning valves so much now. Thanks
Thank You for the informative video. Keep up the good videos. Have A Good Day! 🛻🚚🚛
That little tool pops up on amazon if you look up the proportioning valve...i ordered both the other day to delete the abs on my truck!
GREAT Video.
Quality info pimpin thank u save me a headache
I'm getting ready to put a GM product in my Mustang got any warnings
Great info great video!
The pin in my sensor is pushed in an won’t come out. The part is discontinued. Having trouble finding it at the salvage yard. It’s for a 2004 Avalanche. Any help would be greatly appreciated
Those ports can become clogged with sediment if you push the caliper pistons back to put on new pads. Some thing with drum brakes, if you push the wheel cylinders back to allow space for the new shoes, you can push sediment back up and into the proportioning valve which can then clog a port or two ports or all the ports. If that happens, the valve can go off center. A leak can cause the valve piston to go off center as well. The switch mounts on the proportioning valve where there is no fluid. It should be dry in that spot. If not the valve is leaking.
Pulling my hair out! Have an aluminum screw in blocker tool like you mentioned. Can't see the sensor port to check if valve is centered, because of location, but aluminum pin tool screws in the whole way and seems to bottom out. I hate to tear apart the passenger side header downpipe to get to it and all the brake lines connected to the proportioning valve. But what you say makes a lot of sense. And if that tool is not screwed in even 1 or 2 threads more than i can see, then that may be my issue! I'm only going by feel right now and it feels like it is bottoming out but You can see. I may have to start completely over it with this valve.
Question, when the low brake fluid sensor is removed, is there supposed to be any pressure or brake fluid in that chamber? I just did a proportion valve rebuild for an 84 Mustang. Different animal, but same function as the proportion valve requires a set screw to hold the internal piston from moving while bleeding brakes. But after my rebuild, my low fluid switch is leaking brake fluid through the top pins. Not the threads. Does that indicate the rebuild wasn't a success? Right now I have the set screw acting as a plug because I cant used the stock low fluid switch. It's possible that when the torched the lines to get them free, they damaged the plastic sensor, but just the same, I was under the impression there wasn't supposed to be fluid under the switch in the chamber where the sensors prong rests in the V groove.
My rear brake line broke and it was fixed and they bleed the brakes...but the light still there..They told me to buy a new valve...If it push that pin with a tester would it reset?
thanks for taking the time
Do you have to have the valve off the truck to move the shuttle valve? Or can you move it with it completely mounted? Can’t seem to get mine to move back to center
Oh my frickin... THANK YOU!
Can I just put a brass plug in the brake light switch spot since I have different gauges and don't have stock warning lights?
Yup. The warning light switch is not needed for operation. Just make sure the plug does not extend past the internal threads. This way the combo valve still functions as designed.
Combination valve with proportioning valve and a fluid pressure differential valve. Which is the shut off valve. Should also trip a light. The proportioning valve keeps rear wheels from locking up during hard braking.
My wheels are locked. You think this causing it?
Thanks very, good information to know.
Bro I'm hoping this is my problem I have a leak coming from that switch every time I press the brake fluid squrts out. Gonna give this a shot
So/You tried yours during bleeding the rears?
What's good to use/homeaid/to hold it still?
A nail and duck tape it down?
maybe you could use thick zippy tie or a clamp like a large hose clamp you`d find on a manifold inlet to hold the `nail` down.
Here’s some more good info in these magical mystery devices- use a brass one if you can (S-10’s use them), the stock cast iron ones corrode and get gunked up. If you have it off, you can hold it upright and tap it on a hard surface and that should move the valve - if it doesn’t, it’s gunked up inside.
Also that switch is your friend, it’ll tell you when something is wrong or if there is air in the system…I don’t know why you’d make in inoperative! Plus you want that shuttle valve to move, if there was ever a leak.
Could u move it back with air pressue?
If you have repaired the leak you want to open the opposite side slightly while someone press the break pedal, and then close it off. If it's stuck, yes removing the valve and using compressed air can sometimes knock it loose. Then double check the orings, and center it before reassembly. Sometimes when they are stuck it's because the orings are toast, and have adhered to the bore surface. So if it's stuck it's just a good idea to replace the orings.
I have recently found that it is utterly impossible to find that switch for the proportioning valve for a 2004 Yukon, not even the dealerships can get it. Insane
Thanks alot very helpful
Mine just startd to leak from the front where you can reset it when i apply the brake it squirts out fluid what does this mean, how csn it be fixed
Anyone know where the proportioning valve is located on a 06 impala 3.9 v6?
Yeah man the them can be a pain to reset once they move! I see that new Hayes Street strip Clutch pressure plate! We need a one around on the bad 55 machine man! Been a while since ive seen it! Have a good one ✌️
If you, JB Weld that valve switch, you will disable the ability for your valve to move if you lose brakes on either the front or rear meaning the pin won’t move upward FYI
good shit dude, thanks!
I just barely touch the brake and the back tires lock up! it's a 60 chev! any idea's?
Yup. Couple of possibilities. First inspect your setup to make sure it is still stock, and hasn't been "modified" by a previous owner. If it has, or there are missing comments, decide if you want to replace or upgrade to front disks. If go the upgrade route, don't use an adjustable propotiining valve if you plan on it beibg a steet car. Use a disk\drum combo valve, or a disk\disk combo valve if going with a 4 wheel disk setup. Adjustable propotioning valves are good for the race, but suck on the street. Then I would suspect either bad wheel cylinders that don't retract, or a bad combo valve that is allowing full line pressure to build in the rears.
@@williamallen7836 it's modified it was a two wheel now it's a 4 wheel! friends are telling me sounds like a proportioning valve deal! Thanks!
Close the rear bleeder open the front bleeder and smash the brake pedal to the floor three times did the brake light go out or flicker if yes close the front bleeder and open the rear bleeder and let it gravity bleed until solid fluid comes out of all bleeders
My brake fluid was squirts out of the check valve does this mean I need new proportioning valve or does it need to be reset
You either need a new one, or if yours uses standard orings. Just disassemble, clean it, and put in new orings. Basically your orings gave hardened, and developed a flat surface. This allows break fluid to enter ware it shouldn't be. Some older combo valves that use cup seals at either end still have rebuild kits that come with new cup seals. Hope this helps.
Ira a pisser ain't it.
Thanks for sharing
I have 1993 Dakota - same issue..
great info subscribed
Thanks so much
Great job man
My man!
I thought that was 4 a panic stop...so all the fluid pushes to the front of the car
Thanks
It's a combination valve do not leave your tool in it it will not function properly
This is the exact problem. I’m having right now.🤬
Did you just save me hundreds of dollars
Dude!
What a horrible design by GM! Why would they not make this thing automatically reset.
So this is not so fucking painful, just choose double speed on video playback.
Amazon tool 7 dollars aluminum
Don't buy american. Every vehicle made in america has these insanely difficult to repair.and they need constant repair.
These long adds suck ! Only You can stop this by letting u tube know it sucks ! SpeK up
Thank You for the informative video. Keep up the good videos. Have A Good Day! 🛻🚚🚛