My '97 Z28 smokes when you start it, and even when it's idling. You drive it 30 miles, shut the car off, restart it a minute later and it's smoking again. I called my engine builder and he swears it's a leaking intake manifold letting oil into the cylinder. The spark plugs are completely dry, he tells me there isn't enough oil being burned for you to tell if it's an exhaust valve seal or an intake manifold gasket gone bad. It is only smoking from the left bank. What do you guys think?

 

Any mods?

 

CC503, 1.52 comp roller rockers, pcmforless tune, pacesetter long tubes, double catted y pipe, otherwise stock. I just pulled the intake manifold after speaking to my engine builder. He swears on his life the intake manifold gasket will be leaking on one side or the other. I can't tell just by looking at the gaskets, but I guess anything is possible. My spark plugs are dry, so I asked him about that. He told me there wouldn't be enough oil to tell that way. I'm gonna go get some new intake gaskets and see if that solves the problem. If not, i'm onto exhaust valve seals I guess.

 

Any update? Just curious if an internal oil leak can cause a split blm etc.

 

I called my engine builder and he swears it's an intake manifold gasket on the driver's side not sealing properly, letting just enough oil into one cylinder to smoke. Cannot see the smoke after the car is warmed up, maybe the cat is burning off that trace amount of oil. I know it's not rings, the car just runs too good for that. I have been told that maybe my rings are not sealing properly because they are chromoly. I am currently running 30w non-detergent oil to try and break the rings in more. The only other thing I can think of that it might be is an exhaust valve seal, but who knows which cylinder it is. I'm not all that worried about it, it is still using some oil but not much, and it's more of a weekend car now that gas prices are $4/gallon.

 

If it is a valve stem seal, that cylinders plug will be oil soaked, probably

 

All the spark plugs are completely dry and look great. If it is leaking oil through a valve seal, it is only a drop or two, just enough to put off a little smoke.

 

One last thing, did you have low tension oil rings put in when this was built.

 

I installed whatever the engine machine shop ordered for me. They were the MAHLE brand rings.

 

Understand. Mine were SRP low tensions and it did the same thing as yours and used about a quart every 500 miles on normal driving.
Couldnt hurt to ask them

 

So what did you end up doing to fix the problem? I'm not dropping the engine again just for that. They don't sniff for smog here, they only plug into the port & check for trouble codes. I have been told if the rings are made of chromoly they always have problems sealing to the cylinder. I have switched from detergent 5w30 oil to straight 30w
non-detergent to help scuff the cylinders and rings with a little bit more aggressive oil. My understanding is that the detergent oil has too much soap in it to seat rings properly. So far, it seems to be helping on how much oil it's burning. Pretty discouraging to have a brand new engine burning oil, you know?

 

I re-ringed it as this was the only way to fix it. I had catch can, and the rings were tight at .018 on ll three. Low tension uses oil, that's it. Chromoly will seal up if done right.