Big Block oil consumption problem with pics

[G A.]

Re: Big Block oil consumption problem with pics

the valve guides in a BBC were bored after installed in the heads and sometime the bore was not concentric with the outside dia. this is one reason you have to use guide liners in the original guides to keep the valve on the same center line as original or you will have a problem with the valve seat and the valve being way off center. don't as me how i know this.

Clem, how would I determine if this is the case here? The rebuilder is of no help.

[Joe L.]

Re: Big Block oil consumption problem with pics

Thanks Joe,

I forgot about thin wall guides.
The rebuilder didn't log those kinds of details and says they can't recall. I'll still have to remove a spring to see. I am very tempted to pull the heads and have them built back to specs. I think I would rather spend some money and know what I have rather than try to resolve one problem only to then discover something else, like a worn valve.

Is there a machine shop in Houston that you or another member might recommend?

Dan------

I'm just going to caution you on one thing: I think it's a fine idea to remove the heads and bring them back to new spec in every way. However, don't be surprised if after you do this you still have the same problem. I once "chased" this problem on a small block. I have reported on this several times before and I'm not going to get into it again here in detail----the details are somewhere to be found in the archive. However, a FEW of the things I did were to replace the rebuilt heads with with brand new heads with all new parts, replace the manifold TWICE, use every conceivable type of valve seal, use every conceivable type of intake manifold gasket, use every conceivable type of sealer, and try every different calibration PCV valve made that had a configuration I could use . Nothing worked. After each try (and there were probably 25-30 "stabs" at it) oil consumption would be about 1 quart in 300 miles.

Finally, I figured it had to be the rings even though the kind of conditions I was seeing on the back of the intake valves wouldn't be explained by bad rings and the engine had perfect compression. But, I convinced myself that it just had to be bad oil control rings---there was nothing left to do. So, I re-ringed the engine. No change in oil consumption afterwards. So, I gave up.

I sincerely hope that you don't end up having to go through what I did to get the problem solved. However, just be prepared for the same ending.

I've got to say that my "escapades" trying to resolve this problem was one of the most frustrating experiences of my life. I'll NEVER, EVER forget it.

[Domenic T.]

Re: Big Block oil consumption problem with pics

Joe, you did everything,
I was waiting for the happy ending.
All that didn't solve the problem on the SB?

DOM

[G A.]

Re: Big Block oil consumption problem with pics

Wow Joe, and now I've got to try and get a good nights sleep after that?
I'm sure I won't have that happen to me. I'm sure I won't have that happen to me. I'm sure. I'm sure.......................................

[Joe L.]

Re: Big Block oil consumption problem with pics

Joe, you did everything,
I was waiting for the happy ending.
All that didn't solve the problem on the SB?

DOM

NOPE! Never. I still have that engine here and someday I'm going to "autopsy" it and see what I can find out.

[Clem Z.]

Re: Big Block oil consumption problem with pics

NOPE! Never. I still have that engine here and someday I'm going to "autopsy" it and see what I can find out.

2 things to check is con rod alignment and cylinder perpendicular to the crank center line as this will side load the piston causing the rings not to seal.

[Clem Z.]

Re: Big Block oil consumption problem with pics

Clem, how would I determine if this is the case here? The rebuilder is of no help.

this would not cause your oil problem as what it caused was the valve seats in the heads had to be moved so much that the CCs in the chamber would be way off from the others

[G A.]

Re: Big Block oil consumption problem with pics

Would you fellows consider the following shots of two exhaust valves to have leaking guide seals in need of replacement?

[Joe L.]

Re: Big Block oil consumption problem with pics

Would you fellows consider the following shots of two exhaust valves to have leaking guide seals in need of replacement?

Dan------


I don't think this is much of a problem. Actually, it's good to have a little lubrication on the exhaust valve stems. However, if you convert the intake valve seals to the stock, umbrella type, you would be replacing all the valve seals. The stock, umbrella type seals were used on all valves.

[Edward J.]

Re: Big Block oil consumption problem with pics

Dan, if you do pull the cylinder heads there is a way to tell if there is a ring problem , once the head is removed the outter circumference of the pistons will be wet with oil.

[Joe L.]

Re: Big Block oil consumption problem with pics

Dan, if you do pull the cylinder heads there is a way to tell if there is a ring problem , once the head is removed the outter circumference of the pistons will be wet with oil.

Edward------


Even though in desperation I once considered a ring problem to be a possible source for my oil-burning problem, rationally there's no reason that a ring problem should cause a build-up of caked-on, burnt oil on the port side of the intake valves and, certainly, not result in oil-wetted intake ports in the heads and intake manifold.

[Edward J.]

Re: Big Block oil consumption problem with pics

Edward------


Even though in desperation I once considered a ring problem to be a possible source for my oil-burning problem, rationally there's no reason that a ring problem should cause a build-up of caked-on, burnt oil on the port side of the intake valves and, certainly, not result in oil-wetted intake ports in the heads and intake manifold.

Joe, as I stated in my prev. post, The valves are very wet and have alot of deposits on the intake valves. as you to stated also, If Dan does pull the heads its will be a easy look to the piston tops to see if just maybe there is any issues. Not everyone knows what to look for with bad rings.

[Joe L.]

Re: Big Block oil consumption problem with pics

Joe, as I stated in my prev. post, The valves are very wet and have alot of deposits on the intake valves. as you to stated also, If Dan does pull the heads its will be a easy look to the piston tops to see if just maybe there is any issues. Not everyone knows what to look for with bad rings.

Edward-----


Yes, I was not implying that you gave bad advice or that he shouldn't check what you said. He could have ring problems as ANOTHER problem and he might as well check that while the heads are off, especially as simple as it is. Whether, or not, he has a ring problem, though, I think he also has a top engine-sourced oil control problem. So, even if he finds that there is a ring problem, he can't really figure that's the WHOLE problem.

[Clem Z.]

Re: Big Block oil consumption problem with pics

there are different tension of oil ring expanders and if you use the light tension one you will burn oil as GM found out in the 2001 ZO-6 corvettes. also the second ring is a oil scraper and if installed upside down you will also use oil because it does not wipe enough oil off of the cylinder walls. GM changed both these rings to fix the oil burning problem in the ZO-6

[G A.]

Re: Big Block oil consumption problem with pics

Joe/Ed

Thanks for the reply. I was hoping that the exhaust valves would be the determining clue here. I can't recall if exhaust valve stems should be dry on an 800 mile overhaul. Some oil should be on the stems, I'm just not sure what the evidence suggests. So to recap, here's what I have:

1. Approximately 350 miles to a quart of oil
2. Oily intake runners in each head, at each cylinder
3. Oil build up on the intake valves
4. Oil on all spark plug threads
5. Clean, white/brown electrodes on all plugs
6. Some oil streaking on the exhaust valve stems
7. Intake gaskets were well sealed/stuck to the heads on the upper edges
8. Gaskets were very easy to clean off the heads on lower edges
9. Gaskets were not stuck at all to the intake manifold
10. No smoking on start-up, warm or cold
11. A momentary oily smell after throttle release at higher RPM's (4000+)
12. Everything appears new in the engine save for three valve guides as appears in the photos earlier in this post.

Hmmm.........