1G New Head, Valves Not Seating..

[90_GSX_DSM]

Alright, where to start? The car is a 90 GSX. Decided to build a new head this spring which seemed to be in better condition that my previous. Upgraded springs at the same time. Specs on the head are Kelford 272's, Kiggly beehives(brand new), and Manley standard sized valves.

Got the head back, fired up the car and it ran super rough and was burning an insane amount of oil. Narrowed the problem down to the head by removing the turbo with the same results and performing a leak down and compression test. Leakdown showed leakage in between cylinders and valves, intake and exhaust.

So naturally I took the head back off to inspect for something obvious. Only thing I noticed is that the head gasket didn't seal which I believe was the cause of the oil burning. So I took the head back to the shop to get it checked out. They checked everything out and didn't find anything wrong with the head. They told me I hadn't used enough copper spray and I needed to torque my l19's to 105 ft lbs. So whatever that doesn't explain why the valves weren't sealing but I gave it another try.

Re-installed the head as instructed. No more leakage in between cylinders but the valves still weren't sealing. I was pumping 80 psi into the cylinders and was getting anywhere from 40-60 psi out. Leaking through the intake and exhaust valves. Called the shop back and explained what I was experiencing and they said that there could be some grinding compound or copper spray on the seats causing them not to seal properly and that running the car for a bit should take care of whatever was causing them not to seal.

I almost took that advice and put everything back together but I just didn't feel confident that it would sort itself out as they suggested. I wanted to get a second opinion pretty much and took it to a local machine shop and explained everything to them. He went back through the head, re-lapped the valves, inspected the valves, seats, guides, and nothing looked out of wack to him either. Pretty much ended up telling me the same thing the previous shop did.

So okay I pick the head up today and re re install it. Just torqued down, with no cams or anything in it so valves should be 100% closed. Leaked it down and you guessed it, same result. Maybe a bit healthier but still leaking about 20psi per cylinder out the valves. So I turned the block over so the pistons were all even and down in the cylinders so I could knock the valves off the seat with an extension and rubber mallet. Did this several times to each valve on each cylinder and it did help but only 5-10 psi which like I said still leaked about 20 psi.

Has anyone ever had experience with this happening? If it were one or two valves I wouldn't think nearly as much of it and I'd just slap it together and think it could work itself out. Or if it was only leaking 5 to maybe 10 psi then too. I leaked the motor down before the winter and it only leaked 2-3 psi per cylinder through the rings on a cold motor. Was with the previous head but same valves. Leak down tester itself I thought could be the issue but with not having either manifolds on it makes it very easy to hear/feel all the air leaking past the valve seats.

I'm at the point where tomorrow I'm ready to throw it all together and just run it and hope that it sorts itself out but my head is telling me that's going to be a waste of time. Please tell me someone out there has came across this before and it just happened to seal itself after running . I'm at a complete loss. Any input is appreciated.

Thanks!

By the way, this is not a thread made to discount either shop or to bash any shop. I just really feel like I'm in a tough situation and I'm desperate for some answers. I've had nothing but success with dealing with both shops in the past and the fact that they both didn't find an issue so I know this is something I'm making a big deal out of for nothing or something that's very rare.

 

[yhype]

You are remembering to re-set the gauge each time you use the leak down test right(i think most usually supposed to be at 100 psi)? I know that on my own personal leak down tester that 0-10% is just to get the gauge set and anything below 40% is considered low. By the sounds of it you should be fine, but if you wanted to perform another test on it before you reinstall it, you could always do the old school trick and install the spark plug, flip the head upside down and fill the combustion chambers with water and monitor if any leak and trace it from there. Hope this helps.

 

[90_GSX_DSM]

You are remembering to re-set the gauge each time you use the leak down test right(i think most usually supposed to be at 100 psi)? I know that on my own personal leak down tester that 0-10% is just to get the gauge set and anything below 40% is considered low. By the sounds of it you should be fine, but if you wanted to perform another test on it before you reinstall it, you could always do the old school trick and install the spark plug, flip the head upside down and fill the combustion chambers with water and monitor if any leak and trace it from there. Hope this helps.

Thanks for the quick reply! It sounds like our leak down testers are way different. I have a Jegs tester I've been using for years. No need to reset, there is a regulator knob that you open to let air into the cylinder and close to set back to 0 psi. It has two gauges, the first to show how much psi you're letting in and the second to show how much the motor is keeping in.

Like I said if I literally couldn't hear or feel air leaking past the valve seals I would suspect a faulty tester but that's far from the case. I actually did try that test with the water and it seemed to hold the water level well. But that's under 0 pressure and isn't air more thin than water?

 

[Greedy Pimp]

You need to run the motor and get it hot before you do a leak down test. The air is pushing past the piston rings because nothing has expanded, metal expands when it is heated up. If you want to check the head and see if the valves are seating correctly pull the head and spray some carb or break cleaner in the ports and check if it leaks past the valves.

 

[90_GSX_DSM]

Even with the motor being cold it's not pushing much past the rings. But anyway that's getting off topic. Like I said before when I pressurize the cylinders I can literally easily FEEL and HEAR air leaking past the seats. This is with no exhaust or intake manifold.

Have you ever heard of valves freshly lapped into a head not sealing like this until the motor has been ran?

 

[Greedy Pimp]

Is this on every valve? I've seen it before where a machinist could not cut the seats right because of his tooling was jacked up and had someone ealse do the job. Pull out a valve and inspect lap it your self if you can. What it sounds like they dident cut the seat right or did a poor job laping the valve by what your describing. It's weard because too shops took a look at it and both said it was ok.

 

[90_GSX_DSM]

Is this on every valve? I've seen it before where a machinist could not cut the seats right because of his tooling was jacked up and had someone ealse do the job. Pull out a valve and inspect lap it your self if you can. What it sounds like they dident cut the seat right or did a poor job laping the valve by what your describing. It's weard because too shops took a look at it and both said it was ok.

There are valves that are clearly worse than other ones, but I'm not convinced that it's every valve. It seems that the intake side is a bit worse but there is still leakage on the exhaust side. There are some valves where I can't feel or hear them leaking but that's definitely not an exact way of measuring so... Yea.

Also seems weird to me because I had another shops opinion. He actually specifically said that the seal looked really good on the valve and the seat. The first shop only inspected the seat and seal when they built the head. The time I brought it back they only checked the surface for warping. But still I just don't see them both missing something as critical as a poor seat especially when I tell them it's going on a high boost, high revving car... Idk... Thanks for the responses Greedy!

 

[90_GSX_DSM]

Well surprise surprise the head didn't magically seal itself just by running it. It's almost impossible to even keep the car running. Have to keep the pedal to the floor to even get a quick little 2.5k rev out of it then it dies, which isn't surprising when the valves are leaking over 30%.............

The head has got to be complete junk that's the only thing it could be. About 1k worth of machine shop work down the freaking drain...

 

[JacksonAuto]

Before pulling the head, do a leakdown test with the cams loosened up and the rockers removed. It's possible that the lifters could be holding the valves open. If the leakdown numbers get better, then try bleeding the lifters, reinstall them with the cams and do the test again. If there is still an issue then it's likely that the valve heights were not set correctly when the head was built.

 

[bryanwheat]

I had a similar issue with a local machine shop. They were the best in the area when it comes to block work, balancing, and surfacing, but their valve guy is just awful. I took a head in for new guides and a valve job. When i got it back i went to do a vacuum test on the valves, no seal whatsoever. I noticed that i could see light thru almost every single valve at one point or another. I then pulled a few valves, marked the seat and lapped it a little. I than saw the issue, the seat was cut incorrectly. After going back to the shop to show them this the guy told me, oh that is normal, than the manager comes out and starts getting mouthy with me for doubting his guy. They then both try to tell me that a properly sealed valve won't hold vacuum or liquid (i was ready to hit someone at this point). After talking with them it turns out that they didn't have the correct size metric pilot to put in the guide to cut the seats so they used a loose fitting standard size pilot. This cause the cutter to just follow the current shape of the seat which was not concentric to the new guides. I grabbed the head, left and have never been back. This experience has literally gotten me out of building engines for the most part. In my area it is near impossibly to get good quality machine work without their stupid opinion. The only other machinist in town won't even machine a 4g63 block for you unless you are buying forged internals because he has seen so many rods break so he says.

 

[boost97gst]

Off topic, but isnt it just insane how machinists are with the 4g engine??? Its like its from another world. They have such a hard time with it and so few know how to build them properly. Its JUST an internal combustion engine with the cams on top. Whats so f ing hard about that? I went through the same shit, OP. Its so frustrating to watch the thousands and thousands of dollars rack up just so you can put hundreds of hours into pointless work. It tests your patience, ill say that. Especially when you can take a camaro or corevette with a 350 SBC in to literally any machinists and he can turn it out perfect. ??

 

[My1GLaser]

Send it to (Dale) BogusSVO!

 

[v8s_are_slow]

Dale is pretty backed up at the moment. He's had my block since Feb. and crank and rods since before then. I paid him a visit this past Friday and hasn't even been able to start putting anything together yet. Not even sure if any machining has been done.

Good luck trying to contact him at the moment.

 

[pacn91]

If you end up removing the head again, you could check for your leaks by spraying the combustion chambers with soapy water and blowing compressed air up the runners. Sometimes the water in the chamber trick takes a while before a leak will seep through. Just another trick...

Aside from looking at the dye or lapped area, I just dont see how they could look at the seat and tell that the valve is sealing....atleast not without a leak test. If a customer is standing there and has a problem, why not show them that it seals up. It shouldnt hurt, right?.....One thing that im curious about and have never really had to deal with is clearance in the stem. Could there be too much clearance in the stem? And would it cause this? Probably not likely but just curious. The long valve comment may be more possible here.

 

[Gearhead4G63]

Dale is pretty backed up at the moment. He's had my block since Feb. and crank and rods since before then. I paid him a visit this past Friday and hasn't even been able to start putting anything together yet. Not even sure if any machining has been done.

Good luck trying to contact him at the moment.

I'm having issues getting ahold of him, he has my 6bolt and 2heads and am getting skeptical, he's been paid, and am trying to get ahold of him to get my block and heads back, is that the issue he's just to busy to return a phone call or email?

 

[Calan]

I went through a similar hell a few years ago. Long story short...

Although it was a very reputable shop, they weren't familar with DSM's and their quirks. When they machined the head for new valve seats, they used a big $$$$ CNC machine and simply indexed off the first valve guide like any other head and went at it. What they didn't realize is that DSM head casting tolerances are all over the place, and you can't rely on things to be where they should. So that (along with a new mandrel that came from the supplier .001" undersized, causing some wobble) allowed the seats to be cut slightly non-perpendicular to the guides, which caused the valves to not seat correctly under operating conditions.

That aside, keep in mind that it is sometimes normal to get valve leakage unless the crank is in a very specific spot, and that depends on the cams, and any ACG settings you may be using. The only way to be sure the valves are truly closed and not leaking is to pop the rockers and pressure test the ports.

In response to a few other points:

1). I don't know what HG you used, but you don't need copper spray on an MLS, and should never have to rely on a certain amount of it to seal any type of gasket. If you have to cake on copper spray to get something to seal, you have other issues.

2). Head bolt/stud torque specs are based on the amount of friction reduction that the lube provides; therefore, the shop can't recommend what you should torque your studs to, unless they asked what lubricant you were using. If they tossed out a blanket torque number without asking that, I wouldn't fully trust much of anything else they say.

3). If the shop said that grinding compound may be causing the valves not to seal and just "run it a while"... well you know where I'm going with that.

Do you know which specific valves are leaking? Are they intake, exhaust, or both? Do the leak-down test results change if you rotate the crank to a different position?

 

[CrashGNX]

doesnt matter what position the crank is in, he tested it without cams even in it. I'd say they screwed up cutting the seats and they are at the wrong angle. find the correct specs and verify, then send the head to Jackson Auto Machine and have them fix it right.

 

[v8s_are_slow]

I'm having issues getting ahold of him, he has my 6bolt and 2heads and am getting skeptical, he's been paid, and am trying to get ahold of him to get my block and heads back, is that the issue he's just to busy to return a phone call or email?

I'm not speaking for him at ALL. When I saw him, he said he's not answering calls right now cause he can't get any work done. Dunno how ya run a business and ignore all calls, text, etc. but it's not my business. All I can say is that I'll be going to get my parts back soon if my engine isn't done soon. Very soon. But hoping he gets it done. I'll just post updates after I know something more. Till then, keeping thoughts and anything else to myself.

 

[90_GSX_DSM]

Thanks for the responses guys, I thought this thread was dead and haven't checked it in days.

Before pulling the head, do a leakdown test with the cams loosened up and the rockers removed. It's possible that the lifters could be holding the valves open. If the leakdown numbers get better, then try bleeding the lifters, reinstall them with the cams and do the test again. If there is still an issue then it's likely that the valve heights were not set correctly when the head was built.

Like I said I already removed the cams and no difference once so ever. I agree I now think it's something to do with the valve heights.

I had a similar issue with a local machine shop. They were the best in the area when it comes to block work, balancing, and surfacing, but their valve guy is just awful. I took a head in for new guides and a valve job. When i got it back i went to do a vacuum test on the valves, no seal whatsoever. I noticed that i could see light thru almost every single valve at one point or another. I then pulled a few valves, marked the seat and lapped it a little. I than saw the issue, the seat was cut incorrectly. After going back to the shop to show them this the guy told me, oh that is normal, than the manager comes out and starts getting mouthy with me for doubting his guy. They then both try to tell me that a properly sealed valve won't hold vacuum or liquid (i was ready to hit someone at this point). After talking with them it turns out that they didn't have the correct size metric pilot to put in the guide to cut the seats so they used a loose fitting standard size pilot. This cause the cutter to just follow the current shape of the seat which was not concentric to the new guides. I grabbed the head, left and have never been back. This experience has literally gotten me out of building engines for the most part. In my area it is near impossibly to get good quality machine work without their stupid opinion. The only other machinist in town won't even machine a 4g63 block for you unless you are buying forged internals because he has seen so many rods break so he says.

Unfortunately my issue isn't as obvious as yours. I inspected the head a bit myself while it was off. Everything looks good to the naked eye and the valves hold unpressurized water in the combustion chamber. Which makes sense because according to the leakdown the valves are really close to sealing correctly but something is not quite right. Like I said the valves are holding almost 60% which is enough to make finding anything obvious hard but enough to make the motor run like complete crap, and that's an understatement.

Off topic, but isnt it just insane how machinists are with the 4g engine??? Its like its from another world. They have such a hard time with it and so few know how to build them properly. Its JUST an internal combustion engine with the cams on top. Whats so f ing hard about that? I went through the same shit, OP. Its so frustrating to watch the thousands and thousands of dollars rack up just so you can put hundreds of hours into pointless work. It tests your patience, ill say that. Especially when you can take a camaro or corevette with a 350 SBC in to literally any machinists and he can turn it out perfect. ??

Yea man it completely sucks. I've been in the game for so many years I thought I was done with this kind of bullshit. I pay good money so I don't have to go through this stuff. Now because of this the head has been on and off about 4 times, wasted money on head gaskets not to mention the time and energy wasted. It's so unmotivating...

If you end up removing the head again, you could check for your leaks by spraying the combustion chambers with soapy water and blowing compressed air up the runners. Sometimes the water in the chamber trick takes a while before a leak will seep through. Just another trick...

Aside from looking at the dye or lapped area, I just dont see how they could look at the seat and tell that the valve is sealing....atleast not without a leak test. If a customer is standing there and has a problem, why not show them that it seals up. It shouldnt hurt, right?.....One thing that im curious about and have never really had to deal with is clearance in the stem. Could there be too much clearance in the stem? And would it cause this? Probably not likely but just curious. The long valve comment may be more possible here.

I agree with you 100%. I haven't done that exact test but something similar. With both manifolds off I sprayed brake clean in the runners and pressurized the cylinders. On Both intake and exhaust sides the brake clean was being spit back out at me. Some valves however did seem to be sealing more than others and possibly all the way. But more were leaking than not, that's for sure.

Bottom line is I shouldn't be having to do any of these tests because the machine shop should have checked this head thoroughly the first time I brought it back.

I went through a similar hell a few years ago. Long story short...

Although it was a very reputable shop, they weren't familar with DSM's and their quirks. When they machined the head for new valve seats, they used a big $$$$ CNC machine and simply indexed off the first valve guide like any other head and went at it. What they didn't realize is that DSM head casting tolerances are all over the place, and you can't rely on things to be where they should. So that (along with a new mandrel that came from the supplier .001" undersized, causing some wobble) allowed the seats to be cut slightly non-perpendicular to the guides, which caused the valves to not seat correctly under operating conditions.

That aside, keep in mind that it is sometimes normal to get valve leakage unless the crank is in a very specific spot, and that depends on the cams, and any ACG settings you may be using. The only way to be sure the valves are truly closed and not leaking is to pop the rockers and pressure test the ports.

In response to a few other points:

1). I don't know what HG you used, but you don't need copper spray on an MLS, and should never have to relay on a certain amount of it to seal any type of gasket. If you have to cake on copper spray to get something to seal, you have other issues.

2). Head bolt/stud torque specs are based on the amount of friction reduction that the lube provides; therefore, the shop can't recommend what you should torque your studs to, unless they asked what lubricant you were using. If they tossed out a blanket torque number without asking that, I wouldn't fully trust much of anything else they say.

3). If the shop said that grinding compound may be causing the valves not to seal and just "run it a while"... well you know where I'm going with that.

Do you know which specific valves are leaking? Are they intake, exhaust, or both? Do the leak-down test results change if you rotate the crank to a different position?

I'm still not going to mention any shop names because I still don't know the issue and I'm not one to go out bashing a shop that before this I've had nothing but success with. And they specifically specialize in DSM's btw which is another reason why this is shocking to me. It definitely sounds like we had a very similar problem. Very convinced that the valve seat isn't cut right of the valve heights are wrong. I'm going with the ladder because like I said i did get the second opinion at the other machine shop and he said the seal on the valve seat looked real solid.

1). I used a Mitsu MLS. I've honestly never heard anyone say you don't need copper spray on a metal HG. I've always used it but pretty sparingly and never had any issue. The gentleman at the shop who told me this is very reputable and although I agree with you in that you shouldn't need to cake it on to get a proper seal I did as he said because that's the shop who did my work and I wanted to do everything as he said so I couldn't be blamed.

2). That was all discussed when I talked to him I just didn't go into detail in this thread.

3). I couldn't agree with you more...

Both intake and exhaust valves are leaking. I didn't document which exact valves are leaking but it's the majority. I leaked it down with the crank in at least 3 different positions and same results.

doesnt matter what position the crank is in, he tested it without cams even in it. I'd say they screwed up cutting the seats and they are at the wrong angle. find the correct specs and verify, then send the head to Jackson Auto Machine and have them fix it right.

Thanks for actually reading my post before you replied. That is one of two possibilities. I don't have any more money to just give another machine shop to build this head for the third time so I'm just going to pray that the original shop will agree to find the real issue and make things right...

 

[boost97gst]

Fwiw, I havent read about spraying copper on a MLS either. Mine wasnt sprayed and held over 30psi juuuuust fine. Regular arp studs. Just my .02, but hey, if it works it works and this isnt even your problem, its in the head, or should i say, the WORK done to the head.

 

[90_GSX_DSM]

Fwiw, I havent read about spraying copper on a MLS either. Mine wasnt sprayed and held over 30psi juuuuust fine. Regular arp studs. Just my .02, but hey, if it works it works and this isnt even your problem, its in the head, or should i say, the WORK done to the head.

Yea, I mean obviously I'm sure it works for some people but I personally don't know anyone who doesn't spray their metal HG. Everyone has a way of doing things the way it works best for them and until this past time I never had issues with a HG sealing.

With the bind I'm in now I'm probably going to go with a composite just to hopefully get me to the shootout. I've had good luck with composite gaskets in the past pushing 30 psi. This whole situation just really blows and I've never seen anything like it before. Glad to know that there are a few people that had a very similar issue though. Hopefully this week I can finally get to the bottom of it...

 

[NHerron]

Guess I got lucky out here in V8 country, when I got my head back I simply had to do some extra lapping on just couple of valves. I let WD-40 sit in all intake ports for two nights, flipped and did the exhaust. Only a couple leaked. Lapped a bit and no leak. Leakdown test on engine stand had some leakage though. Machinist instructed to strike valve to hopefully seat better, didn't make much difference. I broke engine in motoman method, rev limiter was found. Anyway, 100 mile leakdown test was fantastic, basically all cylinder (minus ring gaps) leakage. Something like 8% I'd have to check. Valves didn't leak at that point, 100psi.

Of course I f***ed that all up tuning with old unsupported stuff and found out what the world of preign and detonation is all about. Now I'm somewhere like 18% don't quote me. Oh well now I know, but at least dipstick ain't horny yet.

Anyway hope that helps somehow.

 

[90_GSX_DSM]

Guess I got lucky out here in V8 country, when I got my head back I simply had to do some extra lapping on just couple of valves. I let WD-40 sit in all intake ports for two nights, flipped and did the exhaust. Only a couple leaked. Lapped a bit and no leak. Leakdown test on engine stand had some leakage though. Machinist instructed to strike valve to hopefully seat better, didn't make much difference. I broke engine in motoman method, rev limiter was found. Anyway, 100 mile leakdown test was fantastic, basically all cylinder (minus ring gaps) leakage. Something like 8% I'd have to check. Valves didn't leak at that point, 100psi.

Of course I f***ed that all up tuning with old unsupported stuff and found out what the world of preign and detonation is all about. Now I'm somewhere like 18% don't quote me. Oh well now I know, but at least dipstick ain't horny yet.

Anyway hope that helps somehow.

Thanks for chiming in Herron. Do you have any idea how much you were leaking before you re lapped any of the valves in? I've essentially had two machine shops lap these valves in with the second one saying the seal looked really good when he lapped them back in. I as well was instructed to tap of the valve to knock them off of their seats to hopefully raise compression but it didn't really do anything. With the valves leaking 30% it's impossible to keep the motor running. I don't know much about installing valves with the proper valve heights but that seems more plausible than the valve seats being cut wrong. If the valve seats we cut wrong or if the valves are seating on the wrong angle wouldn't that show while lapping the valves in? I'm assuming if the valve height wasn't measured/done correctly it could cause the valve to stick partially open? Also is it crazy that almost ALL the valve heights would have been messed up? I am re using these valves btw. Manley standard sized valves. Ran great in my last head with my bc springs. I have Kiggly beehives now too...

 

[91-GS]

Was going to say that valves might be bent (from a previous timing belt mishap, or something similar) but it sounds like valves are new, so that theory is out of the question.

 

[90_GSX_DSM]

Was going to say that valves might be bent (from a previous timing belt mishap, or something similar) but it sounds like valves are new, so that theory is out of the question.

Valves aren't new. Used them on my previous head. But with all this trouble I've been going through they have been checked by 2 machine shops so that is very unlikely.