still using oil....
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Pro
Joined: Oct 1999
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From: Nashua NH
still using oil....
After sending out my heads and redoing everything from the cam up... I'm still using oil as bad as before. Before I disassembled everything, I did a compression test. Lowest cylinder was 140, highest was 165. I didn't do a leakdown test, however... I'm thinking that my compression rings might be OK but the oil control rings are junk. Thoughts, anyone??
Thread Starter
Pro
Joined: Oct 1999
Posts: 515
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From: Nashua NH
Re: still using oil.... (bogus)
No leaks;
New oil pan, rear main, front crank, intake....
I can smell burning oil when I get on it. I just can't understand why my compression test results were so good!!
Now I have to decide if I should tear it down now, or wait until the fall...
New oil pan, rear main, front crank, intake....
I can smell burning oil when I get on it. I just can't understand why my compression test results were so good!!
Now I have to decide if I should tear it down now, or wait until the fall...
Race Director
Joined: Sep 2000
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From: The Top of Utah
Re: still using oil.... (Mark85Vett)
I think it's more than just oil rings. With a 15 pound difference and only 140 on the low side, I think it's short block time. Very often on a high mileage engine, fresh heads will over power the rings. Unfortunately, I'm in the same boat. With 140,000 miles I burn a quart every 4-500 miles. I know a good share is going down the valve giudes, but I also know that with a valve job I would end up like you. I have two cylinders at 165 and six at 175. People have been telling me for a couple of years to change the timing chain and sprockets, before I have a disaster. With all the work involved doing just the timing parts, and the general condition of the engine, I've decided to wait until I can do it right...or it HAS to be done. The hand writing is on the wall. I think you know what you're going to have to do. If not now, soon. Me too. Good luck.
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Re: still using oil.... (CFI-EFI)
I think it's more than just oil rings. With a 15 pound difference and only 140 on the low side, I think it's short block time. Very often on a high mileage engine, fresh heads will over power the rings. Unfortunately, I'm in the same boat. With 140,000 miles I burn a quart every 4-500 miles. I know a good share is going down the valve giudes, but I also know that with a valve job I would end up like you. I have two cylinders at 165 and six at 175. People have been telling me for a couple of years to change the timing chain and sprockets, before I have a disaster. With all the work involved doing just the timing parts, and the general condition of the engine, I've decided to wait until I can do it right...or it HAS to be done. The hand writing is on the wall. I think you know what you're going to have to do. If not now, soon. Me too. Good luck.
I agree completely with CFI-EFI... The rings don't have the strength left to keep up with the freshend heads.
this is common... very common.
time to rebuild the bottom end.
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Pro
Joined: Oct 1999
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From: Nashua NH
Re: still using oil.... (bogus)
I know....I'm kicking myself because I had this arguement with myself several times when I was doing the top end, but i pulled the main caps and they looked OK, my oil pressure runs at 60-65 psi @ 2000 RPM, and the results of the compression test didn't really alarm me too much....but now that everything is fresh upstairs, there's only one place left for that oil to be seeping by......what a drag..... (back to the old drawing board) :nopity
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Re: still using oil.... (bogus)
I have to agree with CFI-EFI completely on this one. Time for a total rebuilt bottom end. Your rings are gone, AND you must have a leak somewhere.
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Joined: Sep 2000
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From: The Top of Utah
Re: still using oil.... (65Z01)
65Z01,
Both. It is VERY evident if, while cruising at a steady speed, I take my foot off of the gas, let it back down, and then hit the throttle. Poof! Blue smoke every where. Last fall when I installed my ported intake manifold, I had the valve covers off. There was NO sign of sludge or build up, anywhere. If you are suspecting oil drain back problems, I don't think so. In my opinion, too many miles, and too many of them one quarter mile at a time. After 140,000 miles and more than 500 passes, it's hard to complain. If you have additional thoughts on the subject, I'm all ears. Thanks for your interest.
Both. It is VERY evident if, while cruising at a steady speed, I take my foot off of the gas, let it back down, and then hit the throttle. Poof! Blue smoke every where. Last fall when I installed my ported intake manifold, I had the valve covers off. There was NO sign of sludge or build up, anywhere. If you are suspecting oil drain back problems, I don't think so. In my opinion, too many miles, and too many of them one quarter mile at a time. After 140,000 miles and more than 500 passes, it's hard to complain. If you have additional thoughts on the subject, I'm all ears. Thanks for your interest.
Team Owner
Joined: Apr 2001
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From: Dallas TX
Re: still using oil.... (CFI-EFI)
My new engine is using a little oil. About .5 quart every 1000-1500 miles. i'm pretty sure that's from some kind of leak. I've noticed a little oil around the front. Gotta add that to my list :rolleyes: :rolleyes: :rolleyes:
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Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: still using oil.... (CFI-EFI)
Actualy I was thinking of my smoking problem near the top end.
I've only seen it going through the traps, when I let off there's a sizable cloud.
I have 113k miles on the drive train and it doesn't seem to realy use much oil. My compression checks had all in the 162-175 range with no two adjacent low. And I just had the intake off and resealed all carefully; no signs of leaks now.
Since I only see it in 3rd gear after a 1/4mi run it's hard to test except at the strip and they're not too happy about that either. I'll try your scenario to see if I can see any puffs of smoke.
Though it doesn't smoke badly on startup I'm thinking of pulling the valve covers and doing the lower seals.
I've only seen it going through the traps, when I let off there's a sizable cloud.
I have 113k miles on the drive train and it doesn't seem to realy use much oil. My compression checks had all in the 162-175 range with no two adjacent low. And I just had the intake off and resealed all carefully; no signs of leaks now.
Since I only see it in 3rd gear after a 1/4mi run it's hard to test except at the strip and they're not too happy about that either. I'll try your scenario to see if I can see any puffs of smoke.
Though it doesn't smoke badly on startup I'm thinking of pulling the valve covers and doing the lower seals.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Re: still using oil.... (65Z01)
At the end of the 1/4, I slip my trans into neutral. I've never let it back down from there. It would be a high vacuum situation, and very likely, the valve guides/seals are the problem. After you've backed down a while, try punching the throttle, and see if it doesn't get worse. Another thought, is that under the high vacuum, the negitive cylinder pressure is over powering the rings. Under that scenario, the rings are going to be sucked up to the top of the ring groove, where they don't run that often. Just a little food for thought. Good luck.
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: still using oil.... (CFI-EFI)
Thanks for the feedback.
We'll see what new lower seals bring. If that doesn't work I'll have to try your shift into N trick to see if I can reduce the smoke enough to run in the Corvette Challenge.
We'll see what new lower seals bring. If that doesn't work I'll have to try your shift into N trick to see if I can reduce the smoke enough to run in the Corvette Challenge.
Burning Brakes
Joined: Feb 2000
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From: SF Bay area, CA USA
Re: still using oil.... (Mark85Vett)
Somethings to check before you tear your engine down. Do a wet and dry compression test. Pull all plugs, disconnect coil, fuel pump etc. Take compression reading, squirt a shot of motor oil in the cylinder and retake the compression test. All readings will probably go up a little bit but a large difference in one will help isolate the problem.
Is your PCV valve sucking up your oil? I believe the stock valve covers have a baffle to keep the PCV from directly sucking up engine oil, have you changed valve covers or removed the baffle?
Could you have a warped intake manifold? If you do it could cause a vacuum leak under the manifold that could suck the engine oil into the combustion chamber. What do the plugs look like?
A valve job can cause a worn engine to burn more oil. I would be sure of the problem before you do a rebuild.
Is your PCV valve sucking up your oil? I believe the stock valve covers have a baffle to keep the PCV from directly sucking up engine oil, have you changed valve covers or removed the baffle?
Could you have a warped intake manifold? If you do it could cause a vacuum leak under the manifold that could suck the engine oil into the combustion chamber. What do the plugs look like?
A valve job can cause a worn engine to burn more oil. I would be sure of the problem before you do a rebuild.
Thread Starter
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Joined: Oct 1999
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From: Nashua NH
Re: still using oil.... (weekendwrench)
It's using the same amount of oil as it was before I did the top end... I tried the wet and dry compression tests and the numbers weren't any better (1-2 psi, that's it)...if there were big differences in the compression numbers (say 40 or more) then I would have no doubt; the only thing I can think of that would eat that much oil in such a short amount of time is oil control rings...92,000 miles; it's time! I'm going to wait until I'm on vacation to do it...I'll just keep adding oil for now