Hi Ivan I have watched you for years but today is the first time I disagree with you that those valve seats look good. When you lap valves in the seat on the head should be a uniform colour with no spots. You start with course and work to fine with the paste. Also by lapping the valves you should assemble the head before fitting and measure the valve lash because you may have the valves you lapped to loose or to tight and you would have to change the shims on those valves before fitting the head. I don't envy on this job and I do get the customer wants a budget job But if the valves are to tight it will have the same problem sooner rather than later.
If the seats are bad enough that fine paste won't give a nice clean sealing surface then the seats need to be re-cut (and these certainly needed it). Coarse grinding paste is an anachronism, trying to use it to clean up badly pitted seats just ends up recessing the valves.
I agree. He knows his electronics but this job is a failure waiting to happen and shouldn't have made it to video. That seat looked awful and the twisting back and forth with the wrong tool did zero to help. The other valves were toast and the seats needed grinding. He should have told the owner that there would be a good chance it needed both heads reconditioned, because they did.
Either the valve lapping stick has disintegrated or its not a proper one? The ones I've used have a suction cup either end (different sizes) to attach to the valve, and you can then use both hands/palms together to spin them at a decent speed. Plus also lifting the valve occasionally to redistribute the grinding compound. It definitely should have a good clean pit-free band around the seat for reliability, once the grinding / lapping is finished.
I have a 2015 Subaru, and the last time I had it at the dealer they asked me to do a warrantied leakdown test, even though I had no issues. Not surprisingly it passed. I wonder if they had a bad batch of valves that year.
I'm sure you're getting a ton of "opinions" on this video lol. I know what it's like working for customers on a budget and sometimes you have to do things that aren't 100% but all we can do is try our best. I'm sure the car will run fine. This is the reality of repairs . 👍
Hi IVAN,I'm afraid your going to get flak on this one.Most guys here that have done this type of repair{lapping valves in}noticed the VALVE SEATS.Any pitting {the dark spots}on the seat also is a place that doesn't transfer heat.OR can still leak pressure.AS for the valves themselves, they are either not heat treated right or crap steel to begin with.Or just a guess this thing burns oil and is forming carbon deposits the the exhaust valves. ALL this is on the assumption the valves have the proper valve clearance specs.Remember as your valve wears INTO THE SEAT the valve and rocker arm clearance tighten up??? keeping the valve with less time ON the seat to cool.But the reality on this car is,this guy is hard up,doesn't have or want to spend for a long term fix,but iv'e done fixes like this that lasted years.But like someone mentioned i too LAP a lot longer 1st coarse then fine.but you did a good job for the guy under the circumstances.thumbs up buddy.
Last year I bought a 2015 Legacy from the auction as a non runner from a Subaru dealer. Engine was dismantled and in the trunk, same issue. One exhaust valve was burned out. Car had 125K miles and was in good shape otherwise. $450 (luckily) bought a used motor with only 17K and it was back on the road. Interesting to see this is a common issue, or will become one as these cars rack up the miles.
The poor seat on the exhaust valve prevents heat transfer to the cylinder head, over heats the valve and resulted in the crack. The real question is why the seats are so bad? This may be a manufacturing issue, especially knowing about the change to the valvetrain on the other bank.
there's a reason it had a new cat on it. ingesting oil bad metal and that cooled egr. cooling the egr gasses allows the vapors to condensate out enough to turn them corrosive.
Those valves are burnt. The 'crack' is where jets of buring gas went out to the manifold when the spark fired. Enough gas to eat away the valve. The seats on the 1st valve shown in the second cylinder is worn out. You can see the seating area is depressed relative to new. Likely the other side is withing a few thousand of doing the same thing. The engine was run hard, and likely overheated(remember the silver-seal found in the water jacket). "Rode hard and put away wet." I hope you are giving zero guarantee as it will likely be back, or will be sold to an unsuspecting Subaru enthusiast who will need to do the rest of the job soonly.
Agree 100%! I noticed the same thing in Part 2. I was wondering why he kept saying this is the updated part number when clearly it was the same number as the old one.
Considering if you remember the end of PT 1 where Ivan wanted NOTHING to do with this repair, he's at least trying to help this customer out whereas most other shops would likely only install a new(er) engine as most shops won't tie up a bay for a car like this for someone on a tight budget. I used to work for used car dealers and we would do jobs like this and the amount of comebacks was very low. As long as your customer fully understands that this type of job is very hard to guarantee then I see no issue. At least we see effort, I know more than a few mechanics that would just slap valves in without any prep.
I am so glad i have a 2001 subaru outback where you dont have to remove the cams to get to the head bolts, they started making things more difficult as the years went by, same with all cars and trucks, its called engineering against the consumer
They want to engineer something that is very overly complex, plus they want to do it spending as little money as possible. That's the sad reality of modern automobile engineering. Over complicated design, with shabby cheaply made parts. One reason I'm such a big fan of Honda. For years, they've made all their own parts, engines, transmissions, and they use forged cranks and rods in every engine, or at least I know they used to.
I always stamp my work "NO GUARANTEE," and never have any issues since I'm the only customer. I had a lot of complaints once, but after some donuts and actually reading the manual, it got resolved to my satisfaction.
Out of all the repairs you have posted, I hope there was no warranty on this one. Sure the repair was driven by the customers budget, but will they be happy with it in a few weeks / month? Hope to see a follow up a few months from now and hope it's all still good, miracles do happen but this one is pushing it. EDIT: Seems to be the consensus here with this one after reading the comments.
If the Subbies have valve shims? That suggest that they need valve adjustments? With the valves that far into the head. That's part of the normal wear and tear process, since the valves rotate in the valve seat. Lean mixtures tend to cause burnt valves also. As with the valve materials. I've done heads like you Ivan. But with old style valve compressors to reinstall the keepers. I used a tall sockets and whacked it and the keepers popped out. Same as you. I removed all of the valves. Used a box upside down and put them in order I removed them. Cleaned the head. Inspected the valve seats. If they were good. I replaced the bad ones and lapped the valve in. Cleaned the head with power washer. Cleaned all parts and installed new seals and used my old valve compressor and got it fixed. I understand the customer not wanting to spend $$ at the dealer. I hope the customer doesn't start blaming you because he wanted to not spend $$ $ for not doing the whole engine? I'm sure the subbie will be ok.
I seem to remember Ford having similar exhaust valve problems back in the 90's, I think that was caused by the valves being faulty from manufacture, with micro cracks in the metal, or poor quality steel. Maybe same cause here. I had to change quite a few exhaust valves on the early ford zetec engines.
Way back in the mid'70's i worked in a automotive machine shop. We had a customer that was in the propane business and they ran their trucks on propane also. They used to burn up exhaust valves big time. Propane burns quite a bit hotter that gasoline. My guess on the Subaru is that it's running too lean but you made a good point on the valve not contacting the seat fully and not transferring the heat sufficiently! Good job!
About lapping the valves; I remember back when I was in high school I was watching a mechanic work on some valves and he had a rubber suction cup attached to the end of a dowel rod and he just rolled the rod back and forth in his hands to lap the valves. Seemed to work really well. I guess that was back in the "old days". 😄
@@ferrumignis I had(have) a crank tool that oscillated back and forth, and 'stepped' the valve around as it was being seated. Suction cup on one end, a crank on the side, and a wooden knob at the top.
I use a drill and a piece of plastic tubing.. place a piece of plastic tubing over the valve stem that fits snug, put the other end of the tubing in the drill. a piece abt 6 inches long is fine, lap them forward, then reverse.. keep doing this until lapped. pushing the valve stem in and out to redistribute the lapping compound.
In Part 4: Good luck getting everything back in with nothing falling out! Could you let us know how many hours it took you to do this "in situ" valve job? Finally, looking at those corroded valves, no wonder Subaru had to change the composition (alloy) of the valves!
Ivan as long the seat is not pitted you can away with install new valve however and did check the valve clearance with head off by reinstall the cam and shims before installing it in the car
Always cut with a coarse medium then fine cutting compound Matey on bad seats like that and wash it all off with brake cleaner and always replace the valve stem oil seals and you may need to resize the shims after
"temporary" is subjective. Left side original valves will probably fail long before the new replacement valves. I made the customer well aware of this...only real long-term solution is an engine that doesn't burn oil :)
@@PineHollowAutoDiagnostics When I was ten years age my brother works with Russian car Moskwitch. He use similar paste for fixing and I don,t know what it is. Moskwiths burn a lot valves because they use 85 octans gasolin there at russians that time and at Finlahd we have 92 octans. It was 60-talet :)
@@murphy1772 Yes in USSR the regular octane was 76 for low-compression engines. I think Moskvitch was designed to run on 92 minimum. My grandfather had a 1987 model, and he used a double head gasket to lower the compression so he could use the cheaper gas hahaha
You did what the customer wanted... get it running cheap! But, I don't think those valve seats looked very good. Just for the edification of your few non-mechanic viewers, when the pits get that deep it's recommended that you cut the valve seats to get them clean and re-profiled. I don't know what the angles for this engine are but, Subaru was very fussy about the earlier 2.5L. If I recall correctly the exhaust seats required four cuts to meet spec. The combustion chamber, top relief, seat, and lower relief cuts were all different. I'm sure your repair will get the owner enough miles to justify the cost of this repair... then, I have no doubt, he'll get rid of it.
I’d probably wager more that this is to get it running to get it sold or traded. Doesn’t seem to make much sense at all to go through the trouble on the repair this way and expect it to last…
Hi Ivan, I was reading through the comments but don't go through all , but based on my knowledge the reason for valve burning is improper shimming on the exhaust valve and overheating over time cause premature failure , if you notice that exhaust valve is thicker than the intake , because it is exposed to more heat so when it's closed it is supposed to stay close a bit longer than the intake to desipate the heat to the cylinder head , if you check any specification on valve clearance you will see that the exhaust have a wider clearance than intake.
Burnt exhaust valves are a classic indication of pre-ignition in the chamber and/or lean fuel air mixtures. Common root cause is running low octane bio-fuels for long periods of time, without refuelling with a fuel of higher octane which will achieve greater calorific values at lower combustion temperatures. Owners manufactured outside the USA, should be aware of high content bio-fuel limitations and their impacts upon fuel systems, engines and catalytic converters.
If the seats are a hard metal like stellite, or powdered metal, things should go well. ( for the price of installing new seats, it is cost effective, if you know someone you can trust to do it right ) But, when the new valves wear in they will sit taller in the spring end. This induces more preload onto the HLA which will resist the combustion forces, since hydraulics is stronger than the combustion. Then, the valve face will glow and fragment again. One has to hone the shims to get perfect hot running lash adjustment. Then the heat transfers to the valve seat completely. Thankfully, the engine isn't a cast iron flat eight, Then you would need a tractor to move the heads.
Possible manufacturer defect. When the 6.7 Diesel engine came out they were dropping exhaust valves and destroying the engines. Ford fixed the issue and hasn’t had any issues with them since. Also the 427 C6 ZO6 had issues with dropping valves too, not sure if it was intake or exhaust. Always enjoy watching your videos, I appreciate how calm you are when faced with these challenging vehicles. I wish I could say I am this calm when I am working on stubborn vehicles.
I almost think that valve failure is from a defect in the metal. Usually if they overheat from a lean condition(like a partially plugged fuel injector), it causes the valve to burn and a chunk will be missing. I've never seen a valve get cracked like this one is. All the ones I have seen had chunks missing.
Thats some straight up old school valve replacement.i am impressed,I haven't seen that in 40 years.assuming it wasn't a long term lean condition I have to figure the valves were made from bad metal,basically someone didn't check the quality of the stock the valves were made of.i have remover many many heads with burnt valves but I never seen that.hope it runs well sir
Because of the configuration of the engine , carbon deposits are more likely to burn on the valve seats , thats why subaru insist on using their upper cylinder cleaner every service to prevent this
I am guessing that the valve was leaking in that one spot, and the heat of the exhaust blow torched it's way through it over time. This could be the result of worn out valve guides or a manufacturing defect that took a long time to develop. In either case, it is important to know that a valve dissipates most of its heat by conduction by making contact with the seat. If it can't do this, either due to a negative valve lash or a guide that lets the valve close a bit too crooked, something like this is the end result over time.
I thought the updated valves were supposed to have E3 on them. It looks like you put E2 valves back in. That definitely looks like a job I wouldn't want to do.
Defective metal or improper heat treating on those old valves. Using both hands to roll valve grinding tool, like you are starting a fire with a piece of dowel, will go a lot faster.
At 160k miles, it would make the most sense from a longevity standpoint to send both of the heads to a machine shop for a complete refurb. As it is, the next valve failure looks imminent. Customer will probably sell the car to some poor sucker.
I personally would gone with ruff paste then fine till ALL the surface was very good then before assembly put in parts washer as one pice of paste left will destroy engine, plus valve clearance done on bench, still nice video
I know you pointed to the head gasket as a possible cause, but is it possible there was a flaw in the casting/bad steel for the valves that would make them more sensitive to degradation due to heat? I might have to visit some Subaru forums to get their take on the 2.5l EDIT: the most common problems with the 2.5 appear to be head gasket, and oil consumption, with ringland problems for the turbo version of the engine. There are anecdotal problems seen for problems with exhaust valves at higher mileages (150K miles and up). Whether this is an endemic problem is unclear, although you'd expect a lot more complaining from owners if the engines failed at 150K miles generally.
That has to be a very satisfying project. Tedious yes but fun too. Thanks Ivan. Could poor quality steel alloy contribute to all the valve corrosion and fatigue?
Hello Ivan and nice work as always. I'm shocked that the valve seat actually survived. WOW! Must be a terribly week (and weak..edit) valve to decay so much and not blow a groove in the seat. Also loved the review on the Lisle keeper tool. I have used sockets and small/heavy hammer for removal, but the install was amazing! Now looking at this tool to purchase. PS: No valve stem seals or not an issue with Subaru? BMW's are terrible with stem seals. P-Chi
I realize this is coming too late, but Subaru Fujibond is the only sealant that works for these motors. Subaru even re-engineered the sealant that was originally used on these motors to improve techs' chances of success resealing these motors. Everything that has come through the door with some other brand silicone has had leaks. But I get it: the budget is the budget. Having work is better than not, but hopefully the customer understands why this repair is only costing what it is.
its not the sealant its people who dont read the instructions and let the sealant set up for the specified time, so it firms up enough to create the proper thickness between the adjoined parts. they apply the form a gasket, immediately tighten the bolts and the sealant squirts out of the space. aluminum parts expand and contract ALOT so the gasket thickness is critical.
I still have Clover Compound and lapping tools from 1980's 😆. We used Dykem Blue, solvent and vacuum to test contact between seat and valve face. Used mostly on heads from pre-unleaded days; no hard seats. Dykem lets you measure contact area and uniformity. Left side probably a ticking time bomb. Maybe time to DETAIL the car and get top dollar while it's running good and a sellers market??
Great philosophy. So some guy on a budget can buy it for his daughter and she loses the engine in some desolate place at night. Hopefully the owner isn't a cheap prick.
@@giggiddy: Welcome to the USED CAR market, Buddy. Better have a mechanic look at that car before you buy it for your DAUGHTER, and hopefully he knows how to tell which cars to PASS on. Otherwise, be sure it comes with a warranty. Patching cars for quick sale is a tradition as old as cars themselves. In the infamous words of Dorothy, "Toto, I’ve a feeling we’re not in Kansas anymore!”
Nothing but respect for Ivan, he's an honest guy and i love this channel but the lapping job could use some improvement. Even if taking the head to the shop wasn't in the budget, lapping could've been done a lot better.
That damage on the valve looks excactly the same as my 1990 Mazda 323 had back in the early 2000's. My car had carburator, without catalytic converter, so the mixture probably wasn't exactly correct, like in fuel injection & O2 sensor systems, and the engine consumed a little oil, but not massive amounts. It had 4 valves per cylinder, and only one exhaust valve in cylinder number 1 was like this. It had about 300 thousand km's at the time, car was about 13 years old. Found out the problem, when the car failed the MOT emissions test :D
Traditionally, exhaust valves always are the ones that fail. Often there will be a slow build up of carbon on the seat(s) that begin over time to hold the valve open far enough to allow combustion gasses to jet out and create a blowtorch effect hence "burning away" the sharp edge of the valve. Your valve has been leaking a while thus removing more & more material. I don't think it is "cracked"....but just "blowtorched" so to speak. This failure is caused by the valve seat being so overly wide that there is too little "edge" where the valve rests, to break off tiny bits of carbon as they arrive. A thinner seat allows for greater closing force per square inch (cc?) allowing the seat to seal better on the valve face. It is necessary to grind and narrow the seats to provide long range longevity of the valve. Other contributing factors might be the tendency, as you point out, of this engine producing a lot of deposits...as shown in the intake body. Lapping in of valves is not considered "effective" on moder day engines with properly ground seat. A new properly narrowed exhaust seat will hammer (drastic word) it's perfect mating surface into the matching valve face shortly upon start up. Lapping is still used as a "marking" process to evaluate that the surfaces are mated well. Jeff Walker, Lakeside, Az.
Very good explanation, Jeff! Unfortunately even with perfect valve seats, this engine is on borrowed time since it burns a lot of oil due to defective piston rings 😔
Still looks like it got hit with debris. These year motors from Japan had bad pcv valves and the broke valves when the pieces of the pcv went downstream. And obviously with finding stop leak the car has been overheated. FYI Victor Reinz made the OEM single layer graphite head gaskets
Hi Ivan thanks for the video 📹 about grinding in the exhaust valves in my opinion you haven't grind in the valves enough as the seats and head should have a grey ring showing i think that the valves will lose some compression regards Tony 😉
umm, that seat is very trashed, it may even be loose in the head after being torched like that. the guide is likely spent also, even if it seems tight and in place. may get by with it like that on an old mower engine, but it wont hold up long on higher compression injected stuff.
Noticed the right angle cordless wrench you were using. Thinking of buying one. Which is more useful, an impact version, or ordinary cordless wrench type ?
In high school (a very long time ago) we lapped valves using that method, but we'd attach a drill to the valve stem and pull on it while spinning the valve with lapping compound on it.
Ivan when you put the form a gasket sealant on you want to wait abt 30 minutes before tightening down, the form a gasket needs to set up, firm up a bit so it creates a seal.. if you tighten right away you will have a very thin film of gasket material and if there is too much tolerance between the parts, u will have leaks,.
I slap it together ASAP after gasket application and have NEVER had any leaks on dozens of jobs...but perhaps for some applications that makes sense :)
@@PineHollowAutoDiagnostics I used to do the same thing, but the directions to let it cure make good sense,. modern engines have closer tolerances generally, so its usually not an issue but I try to eliminate any potential leaks possible. Im getting too old and tired to do it twice. ha manufacturers using form a gasket was a way to save costs, not to increase reliability. I think letting it dry a bit is critical when there is no gasket and all that is used is the form a gasket sealant.
to clarify, when using form a gasket sealant on parts that have NO paper, . cork. or rubber gasket, you must let the form a gasket set up before assembling parts. you are making a gasket, not a gasket sealer,.
make sure its exact same length.. new one obviously longer... ok they look the same... replacement part sheet showed the newer ones were a little longer. that makes me think they are too short and slam till they crack? I mean I have no clue what im talking about. but the spec sheet you showed did show the replacement ones were slightly longer
I did not understand the TSB requiring the exchange of everything in the valve train if you wanted to go with the updated valve. Sorry for the unfounded critique.
Good job Ivan glad you did not send the customer away to a chop shop to turn his engine into a blender. Other shops would have said new engine period. Keep up the good job.
The valve burned because the valve did not transfer the heat to the head (the coolant removes the heat from the head and developed a hot spot. This is usually caused by poor contact with the valve seat. This can be caused by worn guides, bent valve, or seat out of round. I suggest you invest in a Neway valve cutter set (they can also be bought individually, so you can properly cut all three angles on the seat and get the contact exactly in the center of the ground valve surface and get it back to the proper angle and get that seat back in round and making full contact. This is especially important with the burnt valve seat. I didn't see you check valve guide wear either, which could have been the cause of the valve burning. I would have liked to see some oil on the valve stem during reassembly. I admire your electronic diagnostic skills, but there are better ways to replace valves that will make the repair last a lot longer. Pretty Russian
I cant believe so many people are hating on this. Yes the right way would be to get both heads refinished at a machine shop but the customer wants it done cheap. I'm sure it will last a few years. But this is what the customer wants and you did the best you could do on a budget Great work
Thanks John! Yup that's exactly the case here, and customer is very happy with the results :) Too bad they wasted money on the parts cannon before bringing it to me...could have maybe just bought a replacement engine haha
Those are not very good valves are too soft they probably didn’t harden a head when they made them it was supposed to be harder than the valve seat on the head ! keep up the good work
Hi Ivan, I seem to recall back in the day that if you didn't have lead in the gas you needed Hardened valve seats to prevent the type of wear that you have. I am curious if these valves and seats are cheaper quality and are not lasting like they should. What do you think?
I thought the new valves were supposed to be E3 not the same E2. Now I have to go back and look at the part 2 video to check myself. Thanks vlad for all the great videos. I checked video 2 the service bulletin definitely says E3 is the new part and the valve stem was longer by 2.4 mm. I know the part# on the bag was for the new part but I'm concerned that bad parts went back in.
So why didn't you use the new part number valves if they replaced the old valves. I noticed a little bit different length, but maybe a replacement because of the old ones known for burning up like that?
It seems like this engine has sucked in a piece of debris. That cracked valve looks like it slammed down onto a piece of something. I wouldn't be surprised if there's more damage on the other valves too. Maybe a loose intake duct or something, letting in dirt and sand.
This type of valve damage is typical of misalignment of the valve guides to the seats. This prevents the valve from closing fully resulting in excessive heat build up and eventual failure of the valve and/or the valve seat. To properly effect repair, the valve guides should be replaced and machined accordingly prior to replacing the valves.
I had an 88 ford bronco that did this. I worked on it and serviced it. Then some things happened and I stopped taking care of it. It developed a miss after I found a loose spark plug and it also happened the water pump went out and I ran it dry of water. So it had a lot going against it and yeah when I pulled the head the exhaust valve had a v chunk missing.
Hey Ivan. I know your customer wants a budget job and you're doing them a great service getting this engine to run on all 4 again. But I have to agree with the majority here and point out that those valve seats in the head are cooked! No amount of lapping can fix that. If you were to do this job right, you would send the heads to a machine shop and have those valve seats re-ground and new valve shims will be needed to get the valve clearances back to spec. But I understand that your customer is on a tight budget. So, it is what it is. Anyway, what usually causes this is carbon buildup that gets trapped between the valve and valve seat. A hot spot forms around the compression leak and over time, it weakens the valve.
My brother had like a 1995 Subaru and just a few years in the valves all needed redoing. He was a cheap sort so he was not happy paying for that. He also had some early body rust-through but he did get Subaru to pay for that.
The valves were obviously too tight and not seating. The first one you did needs a lot more attention! The seat interface needs to be smooth all the way around on the seat and the valve.
Used to be valves could burn like this from either valve face or seat erosion or both, often caused by having valve seats that relied on leaded fuel, and using unleaded. The cure would be and still is to get hardened valve seats….but what happened here? It’s a Subaru , pretty reliable but when they go bad nobody seems to know why🤔
Hi Ivan I have watched you for years but today is the first time I disagree with you that those valve seats look good. When you lap valves in the seat on the head should be a uniform colour with no spots. You start with course and work to fine with the paste. Also by lapping the valves you should assemble the head before fitting and measure the valve lash because you may have the valves you lapped to loose or to tight and you would have to change the shims on those valves before fitting the head. I don't envy on this job and I do get the customer wants a budget job But if the valves are to tight it will have the same problem sooner rather than later.
If the seats are bad enough that fine paste won't give a nice clean sealing surface then the seats need to be re-cut (and these certainly needed it). Coarse grinding paste is an anachronism, trying to use it to clean up badly pitted seats just ends up recessing the valves.
Agree. BUT I would still drive 2000 miles. As phad to fix my vehicle with 100% honesty. Plus that will force me to take a holiday.
I agree. He knows his electronics but this job is a failure waiting to happen and shouldn't have made it to video. That seat looked awful and the twisting back and forth with the wrong tool did zero to help. The other valves were toast and the seats needed grinding. He should have told the owner that there would be a good chance it needed both heads reconditioned, because they did.
My gut tells me the owner wants the car running for as little as possible.
Either the valve lapping stick has disintegrated or its not a proper one? The ones I've used have a suction cup either end (different sizes) to attach to the valve, and you can then use both hands/palms together to spin them at a decent speed. Plus also lifting the valve occasionally to redistribute the grinding compound.
It definitely should have a good clean pit-free band around the seat for reliability, once the grinding / lapping is finished.
I have a 2015 Subaru, and the last time I had it at the dealer they asked me to do a warrantied leakdown test, even though I had no issues. Not surprisingly it passed. I wonder if they had a bad batch of valves that year.
I'm sure you're getting a ton of "opinions" on this video lol. I know what it's like working for customers on a budget and sometimes you have to do things that aren't 100% but all we can do is try our best. I'm sure the car will run fine. This is the reality of repairs . 👍
Hi IVAN,I'm afraid your going to get flak on this one.Most guys here that have done this type of repair{lapping valves in}noticed the VALVE SEATS.Any pitting {the dark spots}on the seat also is a place that doesn't transfer heat.OR can still leak pressure.AS for the valves themselves, they are either not heat treated right or crap steel to begin with.Or just a guess this thing burns oil and is forming carbon deposits the the exhaust valves. ALL this is on the assumption the valves have the proper valve clearance specs.Remember as your valve wears INTO THE SEAT the valve and rocker arm clearance tighten up??? keeping the valve with less time ON the seat to cool.But the reality on this car is,this guy is hard up,doesn't have or want to spend for a long term fix,but iv'e done fixes like this that lasted years.But like someone mentioned i too LAP a lot longer 1st coarse then fine.but you did a good job for the guy under the circumstances.thumbs up buddy.
Budget or not, when you get inside and see how bad those valves were, it's time to find a way to get those heads to a machine shop.
Totally agree, those valves are living on borrowed time.
maybe the guy is going to trade it in and stick it to a dealer...
Yup. 15 or so hour job is no place to skimp on some machine work
Valve Grind Compound is also good for slightly stripped screws. A little dab on your screw driver gives it a little extra bite on the bit.
Last year I bought a 2015 Legacy from the auction as a non runner from a Subaru dealer. Engine was dismantled and in the trunk, same issue. One exhaust valve was burned out. Car had 125K miles and was in good shape otherwise.
$450 (luckily) bought a used motor with only 17K and it was back on the road.
Interesting to see this is a common issue, or will become one as these cars rack up the miles.
The poor seat on the exhaust valve prevents heat transfer to the cylinder head, over heats the valve and resulted in the crack. The real question is why the seats are so bad? This may be a manufacturing issue, especially knowing about the change to the valvetrain on the other bank.
there's a reason it had a new cat on it. ingesting oil bad metal and that cooled egr. cooling the egr gasses allows the vapors to condensate out enough to turn them corrosive.
Those valves are burnt. The 'crack' is where jets of buring gas went out to the manifold when the spark fired. Enough gas to eat away the valve. The seats on the 1st valve shown in the second cylinder is worn out. You can see the seating area is depressed relative to new. Likely the other side is withing a few thousand of doing the same thing. The engine was run hard, and likely overheated(remember the silver-seal found in the water jacket). "Rode hard and put away wet." I hope you are giving zero guarantee as it will likely be back, or will be sold to an unsuspecting Subaru enthusiast who will need to do the rest of the job soonly.
Did I miss something? You said there's an updated part number of the Valves but you replaced them with the same part number?? Or did I get that wrong?
Yeah that's what I thought.. I mean I thought I saw E3 on the updated version but he put another E2 back in it.. 🤷♂️
It requires a new head assembly. Customer doesn't want to pay it so there's no reason why he should eat the cost of a new head
@@robertvillafan1220- Well if that's what the customer wants to do that's dumb but I never said Ivan should pay for it.
@@robertvillafan1220 I know the customer won't pay for new heads but I just didn't know why Ivan didn't use the updated valves that's all
Agree 100%! I noticed the same thing in Part 2. I was wondering why he kept saying this is the updated part number when clearly it was the same number as the old one.
Considering if you remember the end of PT 1 where Ivan wanted NOTHING to do with this repair, he's at least trying to help this customer out whereas most other shops would likely only install a new(er) engine as most shops won't tie up a bay for a car like this for someone on a tight budget. I used to work for used car dealers and we would do jobs like this and the amount of comebacks was very low. As long as your customer fully understands that this type of job is very hard to guarantee then I see no issue. At least we see effort, I know more than a few mechanics that would just slap valves in without any prep.
Like with Ivan the customer would have had a hard time convincing me to do this job, but he never could have convinced me to just do half the job.
I am so glad i have a 2001 subaru outback where you dont have to remove the cams to get to the head bolts, they started making things more difficult as the years went by, same with all cars and trucks, its called engineering against the consumer
They want to engineer something that is very overly complex, plus they want to do it spending as little money as possible. That's the sad reality of modern automobile engineering. Over complicated design, with shabby cheaply made parts. One reason I'm such a big fan of Honda. For years, they've made all their own parts, engines, transmissions, and they use forged cranks and rods in every engine, or at least I know they used to.
I always stamp my work "NO GUARANTEE," and never have any issues since I'm the only customer. I had a lot of complaints once, but after some donuts and actually reading the manual, it got resolved to my satisfaction.
Out of all the repairs you have posted, I hope there was no warranty on this one. Sure the repair was driven by the customers budget, but will they be happy with it in a few weeks / month? Hope to see a follow up a few months from now and hope it's all still good, miracles do happen but this one is pushing it.
EDIT: Seems to be the consensus here with this one after reading the comments.
If the Subbies have valve shims? That suggest that they need valve adjustments?
With the valves that far into the head. That's part of the normal wear and tear process, since the valves rotate in the valve seat.
Lean mixtures tend to cause burnt valves also. As with the valve materials.
I've done heads like you Ivan.
But with old style valve compressors to reinstall the keepers.
I used a tall sockets and whacked it and the keepers popped out.
Same as you. I removed all of the valves. Used a box upside down and put them in order I removed them. Cleaned the head. Inspected the valve seats. If they were good. I replaced the bad ones and lapped the valve in. Cleaned the head with power washer. Cleaned all parts and installed new seals and used my old valve compressor and got it fixed. I understand the customer not wanting to spend $$ at the dealer.
I hope the customer doesn't start blaming you because he wanted to not spend $$ $ for not doing the whole engine?
I'm sure the subbie will be ok.
I seem to remember Ford having similar exhaust valve problems back in the 90's, I think that was caused by the valves being faulty from manufacture, with micro cracks in the metal, or poor quality steel. Maybe same cause here. I had to change quite a few exhaust valves on the early ford zetec engines.
Way back in the mid'70's i worked in a automotive machine shop. We had a customer that was in the propane business and they ran their trucks on propane also. They used to burn up exhaust valves big time. Propane burns quite a bit hotter that gasoline. My guess on the Subaru is that it's running too lean but you made a good point on the valve not contacting the seat fully and not transferring the heat sufficiently! Good job!
About lapping the valves; I remember back when I was in high school I was watching a mechanic work on some valves and he had a rubber suction cup attached to the end of a dowel rod and he just rolled the rod back and forth in his hands to lap the valves. Seemed to work really well. I guess that was back in the "old days". 😄
Still got my dad's in the tool box different size cup on each end.MISS you Dad.
That's the correct way to lap in valves even today. You can get drill attachments that give the same motion which is a lot less tiring.
@@ferrumignis I had(have) a crank tool that oscillated back and forth, and 'stepped' the valve around as it was being seated. Suction cup on one end, a crank on the side, and a wooden knob at the top.
@@GrumpyUnkMillions so fancy!
I use a drill and a piece of plastic tubing.. place a piece of plastic tubing over the valve stem that fits snug, put the other end of the tubing in the drill. a piece abt 6 inches long is fine, lap them forward, then reverse.. keep doing this until lapped. pushing the valve stem in and out to redistribute the lapping compound.
In Part 4: Good luck getting everything back in with nothing falling out! Could you let us know how many hours it took you to do this "in situ" valve job? Finally, looking at those corroded valves, no wonder Subaru had to change the composition (alloy) of the valves!
Ivan as long the seat is not pitted you can away with install new valve however and did check the valve clearance with head off by reinstall the cam and shims before installing it in the car
Nice job. Looks like that first valve has a lot imperfections in the seat on the head.
Always cut with a coarse medium then fine cutting compound Matey on bad seats like that and wash it all off with brake cleaner and always replace the valve stem oil seals and you may need to resize the shims after
Pine Hollow makes the best holiday specials.
Just a temporary fix. Those exhaust seats needed to be cut to achieve a proper seal ! Just saying !
"temporary" is subjective. Left side original valves will probably fail long before the new replacement valves. I made the customer well aware of this...only real long-term solution is an engine that doesn't burn oil :)
I think the fix was just good enough to sell this turd to some poor sucker.
The paste you're using is still available here in Europe! Same exact metal can and everything :D
Awesome! Love that paste :)
@@PineHollowAutoDiagnostics When I was ten years age my brother works with Russian car Moskwitch. He use similar paste for fixing and I don,t know what it is. Moskwiths burn a lot valves because they use 85 octans gasolin there at russians that time and at Finlahd we have 92 octans. It was 60-talet :)
@@murphy1772 Yes in USSR the regular octane was 76 for low-compression engines. I think Moskvitch was designed to run on 92 minimum. My grandfather had a 1987 model, and he used a double head gasket to lower the compression so he could use the cheaper gas hahaha
Chuck the valve grinding tool with the rubber end up in a variable speed drill, and grind a little more on the valves using a very low RPM>
When I lap valves, I use my cordless drill and chuck the stem after you put the valve in the head. Use the drill to do all the work
You did what the customer wanted... get it running cheap! But, I don't think those valve seats looked very good. Just for the edification of your few non-mechanic viewers, when the pits get that deep it's recommended that you cut the valve seats to get them clean and re-profiled. I don't know what the angles for this engine are but, Subaru was very fussy about the earlier 2.5L. If I recall correctly the exhaust seats required four cuts to meet spec. The combustion chamber, top relief, seat, and lower relief cuts were all different. I'm sure your repair will get the owner enough miles to justify the cost of this repair... then, I have no doubt, he'll get rid of it.
I’d probably wager more that this is to get it running to get it sold or traded.
Doesn’t seem to make much sense at all to go through the trouble on the repair this way and expect it to last…
I bet customer will be selling it as soon as it’s repaired. That’s why I don’t buy used cars anymore.
Hi Ivan, I was reading through the comments but don't go through all , but based on my knowledge the reason for valve burning is improper shimming on the exhaust valve and overheating over time cause premature failure , if you notice that exhaust valve is thicker than the intake , because it is exposed to more heat so when it's closed it is supposed to stay close a bit longer than the intake to desipate the heat to the cylinder head , if you check any specification on valve clearance you will see that the exhaust have a wider clearance than intake.
Burnt exhaust valves are a classic indication of pre-ignition in the chamber and/or lean fuel air mixtures. Common root cause is running low octane bio-fuels for long periods of time, without refuelling with a fuel of higher octane which will achieve greater calorific values at lower combustion temperatures. Owners manufactured outside the USA, should be aware of high content bio-fuel limitations and their impacts upon fuel systems, engines and catalytic converters.
WIth all that stated, seems like the only subarus affected are some forresters, like he said.
Ivan, holding my breath that everything goes well. Looking forward to Part 4. Thanks for Sharing!
If the seats are a hard metal like stellite, or powdered metal, things should go well.
( for the price of installing new seats, it is cost effective, if you know someone you can trust to do it right )
But, when the new valves wear in they will sit taller in the spring end.
This induces more preload onto the HLA which will resist the combustion forces, since hydraulics is stronger than the combustion.
Then, the valve face will glow and fragment again.
One has to hone the shims to get perfect hot running lash adjustment.
Then the heat transfers to the valve seat completely.
Thankfully, the engine isn't a cast iron flat eight,
Then you would need a tractor to move the heads.
Possible manufacturer defect. When the 6.7 Diesel engine came out they were dropping exhaust valves and destroying the engines. Ford fixed the issue and hasn’t had any issues with them since. Also the 427 C6 ZO6 had issues with dropping valves too, not sure if it was intake or exhaust. Always enjoy watching your videos, I appreciate how calm you are when faced with these challenging vehicles. I wish I could say I am this calm when I am working on stubborn vehicles.
I believe the 6.7 was actually dropping valve seats like the 5.7 Hemi was too, causing the valves to meet the pistons with catastrophic results.
I almost think that valve failure is from a defect in the metal. Usually if they overheat from a lean condition(like a partially plugged fuel injector), it causes the valve to burn and a chunk will be missing. I've never seen a valve get cracked like this one is. All the ones I have seen had chunks missing.
that first valve was most defiantly not lapped it should be a continuous grey line that had many defects in the surface of both valve and seat
I remember being the first on the block to have that valve seat tool.
Wicked awesome
I would have definitely shimmed the valves with the head on the table Before installing it.
Thats some straight up old school valve replacement.i am impressed,I haven't seen that in 40 years.assuming it wasn't a long term lean condition I have to figure the valves were made from bad metal,basically someone didn't check the quality of the stock the valves were made of.i have remover many many heads with burnt valves but I never seen that.hope it runs well sir
I don’t know callme an idiot or maybe I missed that step but should the head be machined flat again?
Defective manufacturing of the valve. Burning valves are supposed to be a thing of the past.
Yeah I was really surprised to see this failure on a modern vehicle 😳
Because of the configuration of the engine , carbon deposits are more likely to burn on the valve seats , thats why subaru insist on using their upper cylinder cleaner every service to prevent this
I am guessing that the valve was leaking in that one spot, and the heat of the exhaust blow torched it's way through it over time. This could be the result of worn out valve guides or a manufacturing defect that took a long time to develop. In either case, it is important to know that a valve dissipates most of its heat by conduction by making contact with the seat. If it can't do this, either due to a negative valve lash or a guide that lets the valve close a bit too crooked, something like this is the end result over time.
Hi Ivan bad call those seats needed re cutting all that pitting will lead to the seats burning again, then the shims needed checking,
I thought the updated valves were supposed to have E3 on them. It looks like you put E2 valves back in. That definitely looks like a job I wouldn't want to do.
Ya the revision what Ivan showed us was E3. Not sure 🤔
That is a cool tool. I personally like the C style tool and take my time, also I would install new valve stem seals wile it’s apart
Defective metal or improper heat treating on those old valves. Using both hands to roll valve grinding tool, like you are starting a fire with a piece of dowel, will go a lot faster.
At 160k miles, it would make the most sense from a longevity standpoint to send both of the heads to a machine shop for a complete refurb. As it is, the next valve failure looks imminent. Customer will probably sell the car to some poor sucker.
Only 120k on this one...
I personally would gone with ruff paste then fine till ALL the surface was very good then before assembly put in parts washer as one pice of paste left will destroy engine, plus valve clearance done on bench, still nice video
I bought those same tools to replace a broken valve spring on a Toyota Sienna with the head still installed and they worked amazingly well.
SSHHH Don't tell Scotty 😉😊😂🤣😂
@@stephenjones9153 😂😂
I know you pointed to the head gasket as a possible cause, but is it possible there was a flaw in the casting/bad steel for the valves that would make them more sensitive to degradation due to heat? I might have to visit some Subaru forums to get their take on the 2.5l
EDIT: the most common problems with the 2.5 appear to be head gasket, and oil consumption, with ringland problems for the turbo version of the engine. There are anecdotal problems seen for problems with exhaust valves at higher mileages (150K miles and up). Whether this is an endemic problem is unclear, although you'd expect a lot more complaining from owners if the engines failed at 150K miles generally.
That has to be a very satisfying project. Tedious yes but fun too. Thanks Ivan. Could poor quality steel alloy contribute to all the valve corrosion and fatigue?
Yep, no need for digital torque wrenches still using a Craftsman TW i bought in the early 90`s
Thought I heard someone say they didn't want or have time to do a head job but hear you are somehow you allways get it done.
Hello Ivan and nice work as always.
I'm shocked that the valve seat actually survived. WOW! Must be a terribly week (and weak..edit) valve to decay so much and not blow a groove in the seat.
Also loved the review on the Lisle keeper tool. I have used sockets and small/heavy hammer for removal, but the install was amazing! Now looking at this tool to purchase.
PS: No valve stem seals or not an issue with Subaru? BMW's are terrible with stem seals.
P-Chi
You da man Ivan. From in-depth diag to internal engine service.
Can usually use the tool with hand pressure alone to install the valve keepers , especially on the little engines
I have tried that, but the hammer tap helps the keepers fall into place instantly 👍
Exhaust valves get hella hot. Material is leaving the valve surface. The seats are cooled by conduction with the head.
I realize this is coming too late, but Subaru Fujibond is the only sealant that works for these motors. Subaru even re-engineered the sealant that was originally used on these motors to improve techs' chances of success resealing these motors. Everything that has come through the door with some other brand silicone has had leaks. But I get it: the budget is the budget. Having work is better than not, but hopefully the customer understands why this repair is only costing what it is.
its not the sealant its people who dont read the instructions and let the sealant set up for the specified time, so it firms up enough to create the proper thickness between the adjoined parts. they apply the form a gasket, immediately tighten the bolts and the sealant squirts out of the space. aluminum parts expand and contract ALOT so the gasket thickness is critical.
I still have Clover Compound and lapping tools from 1980's 😆. We used Dykem Blue, solvent and vacuum to test contact between seat and valve face. Used mostly on heads from pre-unleaded days; no hard seats. Dykem lets you measure contact area and uniformity. Left side probably a ticking time bomb. Maybe time to DETAIL the car and get top dollar while it's running good and a sellers market??
Great philosophy. So some guy on a budget can buy it for his daughter and she loses the engine in some desolate place at night. Hopefully the owner isn't a cheap prick.
@@giggiddy: Welcome to the USED CAR market, Buddy. Better have a mechanic look at that car before you buy it for your DAUGHTER, and hopefully he knows how to tell which cars to PASS on. Otherwise, be sure it comes with a warranty. Patching cars for quick sale is a tradition as old as cars themselves. In the infamous words of Dorothy, "Toto, I’ve a feeling we’re not in Kansas anymore!”
@@giggiddy Maybe buy a used car with way less miles? Over 100K is where things definitely need replacing
Nothing but respect for Ivan, he's an honest guy and i love this channel but the lapping job could use some improvement. Even if taking the head to the shop wasn't in the budget, lapping could've been done a lot better.
That damage on the valve looks excactly the same as my 1990 Mazda 323 had back in the early 2000's.
My car had carburator, without catalytic converter, so the mixture probably wasn't exactly correct, like in fuel injection & O2 sensor systems, and the engine consumed a little oil, but not massive amounts. It had 4 valves per cylinder, and only one exhaust valve in cylinder number 1 was like this.
It had about 300 thousand km's at the time, car was about 13 years old. Found out the problem, when the car failed the MOT emissions test :D
Traditionally, exhaust valves always are the ones that fail. Often there will be a slow build up of carbon on the seat(s) that begin over time to hold the valve open far enough to allow combustion gasses to jet out and create a blowtorch effect hence "burning away" the sharp edge of the valve.
Your valve has been leaking a while thus removing more & more material. I don't think it is "cracked"....but just "blowtorched" so to speak.
This failure is caused by the valve seat being so overly wide that there is too little "edge" where the valve rests, to break off tiny bits of carbon as they arrive. A thinner seat allows for greater closing force per square inch (cc?) allowing the seat to seal better on the valve face. It is necessary to grind and narrow the seats to provide long range longevity of the valve.
Other contributing factors might be the tendency, as you point out, of this engine producing a lot of deposits...as shown in the intake body. Lapping in of valves is not considered "effective" on moder day engines with properly ground seat. A new properly narrowed exhaust seat will
hammer (drastic word) it's perfect mating surface into the matching valve face shortly upon start up.
Lapping is still used as a "marking" process to evaluate that the surfaces are mated well.
Jeff Walker, Lakeside, Az.
Very good explanation, Jeff! Unfortunately even with perfect valve seats, this engine is on borrowed time since it burns a lot of oil due to defective piston rings 😔
Keep It Simple. Made it look easy, Ivan ! Those valves will outlast the car and the owner can still afford to put gas in it!😃
Still looks like it got hit with debris. These year motors from Japan had bad pcv valves and the broke valves when the pieces of the pcv went downstream. And obviously with finding stop leak the car has been overheated. FYI Victor Reinz made the OEM single layer graphite head gaskets
Hi Ivan thanks for the video 📹 about grinding in the exhaust valves in my opinion you haven't grind in the valves enough as the seats and head should have a grey ring showing i think that the valves will lose some compression regards Tony 😉
umm, that seat is very trashed, it may even be loose in the head after being torched like that. the guide is likely spent also, even if it seems tight and in place.
may get by with it like that on an old mower engine, but it wont hold up long on higher compression injected stuff.
Understand the customers budget limit... but I can only imagine the other side has issues as well...
We'll take a look at the other side in Part 4 :)
They made a tool to lap in valves, works with a suction cup and it oscillates .
Nothing more abrasive than lapping paste...thoroughly clean & clean again & again !
Noticed the right angle cordless wrench you were using. Thinking of buying one. Which is more useful, an impact version, or ordinary cordless wrench type ?
In high school (a very long time ago) we lapped valves using that method, but we'd attach a drill to the valve stem and pull on it while spinning the valve with lapping compound on it.
Those were small blocks with cast iron heads, not aluminum like these.
Hope you made a disclaimer with customer not having machine shop recondition the head. New keepers maybe??
Ivan when you put the form a gasket sealant on you want to wait abt 30 minutes before tightening down, the form a gasket needs to set up, firm up a bit so it creates a seal.. if you tighten right away you will have a very thin film of gasket material and if there is too much tolerance between the parts, u will have leaks,.
I slap it together ASAP after gasket application and have NEVER had any leaks on dozens of jobs...but perhaps for some applications that makes sense :)
@@PineHollowAutoDiagnostics I used to do the same thing, but the directions to let it cure make good sense,. modern engines have closer tolerances generally, so its usually not an issue but I try to eliminate any potential leaks possible. Im getting too old and tired to do it twice. ha manufacturers using form a gasket was a way to save costs, not to increase reliability. I think letting it dry a bit is critical when there is no gasket and all that is used is the form a gasket sealant.
to clarify, when using form a gasket sealant on parts that have NO paper, . cork. or rubber gasket, you must let the form a gasket set up before assembling parts. you are making a gasket, not a gasket sealer,.
make sure its exact same length.. new one obviously longer... ok they look the same... replacement part sheet showed the newer ones were a little longer. that makes me think they are too short and slam till they crack? I mean I have no clue what im talking about. but the spec sheet you showed did show the replacement ones were slightly longer
Need to lap out all the pitting on the valve seat for a good seal!
Hi Ivan, that all most looks like someone has been running E-85 in that engine and the alcohol has been eating away at the valves.
I did not understand the TSB requiring the exchange of everything in the valve train if you wanted to go with the updated valve. Sorry for the unfounded critique.
For the small cost you should have changed out the valve seals.Maybe not as necessary on the boxer stye motor. Great work Ivan.
Good job Ivan glad you did not send the customer away to a chop shop to turn his engine into a blender. Other shops would have said new engine period. Keep up the good job.
The valve burned because the valve did not transfer the heat to the head (the coolant removes the heat from the head and developed a hot spot. This is usually caused by poor contact with the valve seat. This can be caused by worn guides, bent valve, or seat out of round. I suggest you invest in a Neway valve cutter set (they can also be bought individually, so you can properly cut all three angles on the seat and get the contact exactly in the center of the ground valve surface and get it back to the proper angle and get that seat back in round and making full contact. This is especially important with the burnt valve seat. I didn't see you check valve guide wear either, which could have been the cause of the valve burning. I would have liked to see some oil on the valve stem during reassembly. I admire your electronic diagnostic skills, but there are better ways to replace valves that will make the repair last a lot longer. Pretty Russian
I cant believe so many people are hating on this.
Yes the right way would be to get both heads refinished at a machine shop but the customer wants it done cheap. I'm sure it will last a few years. But this is what the customer wants and you did the best you could do on a budget
Great work
Thanks John! Yup that's exactly the case here, and customer is very happy with the results :) Too bad they wasted money on the parts cannon before bringing it to me...could have maybe just bought a replacement engine haha
Customer is always right!!
I wonder if something kept that valve from spinning and it got hot in that one spot.
Those are not very good valves are too soft they probably didn’t harden a head when they made them it was supposed to be harder than the valve seat on the head ! keep up the good work
Hi Ivan,
I seem to recall back in the day that if you didn't have lead in the gas you needed Hardened valve seats to prevent the type of wear that you have. I am curious if these valves and seats are cheaper quality and are not lasting like they should. What do you think?
That cylinder head should have gone to the machine shop and done right .ivan
You stated you saw shiny stuff in the coolant stop leak possibly you said, maybe this cylinder overheating causing the valve to self destruct.
I usually put the valve stem on the end of my drill and slowly lap it using sound as a guide.
I also spent a lot more time lapping valves. I believe the problem is caused by low octane no lead fuel...maybe even helped along with ethanol.
I thought the new valves were supposed to be E3 not the same E2. Now I have to go back and look at the part 2 video to check myself. Thanks vlad for all the great videos.
I checked video 2 the service bulletin definitely says E3 is the new part and the valve stem was longer by 2.4 mm. I know the part# on the bag was for the new part but I'm concerned that bad parts went back in.
So why didn't you use the new part number valves if they replaced the old valves. I noticed a little bit different length, but maybe a replacement because of the old ones known for burning up like that?
It seems like this engine has sucked in a piece of debris. That cracked valve looks like it slammed down onto a piece of something. I wouldn't be surprised if there's more damage on the other valves too. Maybe a loose intake duct or something, letting in dirt and sand.
Why did you not replace the valve Guides seals while you're there?
This type of valve damage is typical of misalignment of the valve guides to the seats. This prevents the valve from closing fully resulting in excessive heat build up and eventual failure of the valve and/or the valve seat. To properly effect repair, the valve guides should be replaced and machined accordingly prior to replacing the valves.
If the guide and seat were not aligned wouldn't that show up on the shape of the shiny part after lapping?
I had an 88 ford bronco that did this. I worked on it and serviced it. Then some things happened and I stopped taking care of it. It developed a miss after I found a loose spark plug and it also happened the water pump went out and I ran it dry of water. So it had a lot going against it and yeah when I pulled the head the exhaust valve had a v chunk missing.
Hey Ivan. I know your customer wants a budget job and you're doing them a great service getting this engine to run on all 4 again. But I have to agree with the majority here and point out that those valve seats in the head are cooked! No amount of lapping can fix that. If you were to do this job right, you would send the heads to a machine shop and have those valve seats re-ground and new valve shims will be needed to get the valve clearances back to spec. But I understand that your customer is on a tight budget. So, it is what it is. Anyway, what usually causes this is carbon buildup that gets trapped between the valve and valve seat. A hot spot forms around the compression leak and over time, it weakens the valve.
wasnt much carbon on the valves?
@@randy1ization I didn't suggest that this was the case here. It's just that carbon buildup is a more common cause for chipping valves.
My brother had like a 1995 Subaru and just a few years in the valves all needed redoing. He was a cheap sort so he was not happy paying for that. He also had some early body rust-through but he did get Subaru to pay for that.
The valves were obviously too tight and not seating. The first one you did needs a lot more attention! The seat interface needs to be smooth all the way around on the seat and the valve.
Looks like JDM good used engine time, otherwise can let go at any time , these are notorious for headmaster and oil consumption issues too.
I learned early that lugging the engine on a standard tranny car is hard on the exhaust valves. Keep the revs up on long PA hillclimbs!!
Used to be valves could burn like this from either valve face or seat erosion or both, often caused by having valve seats that relied on leaded fuel, and using unleaded. The cure would be and still is to get hardened valve seats….but what happened here? It’s a Subaru , pretty reliable but when they go bad nobody seems to know why🤔