Oil Mist From Muffler Tailpipes

[Ludigdrums]

My '81 seems to spray a mist out of its tailpipes. I thought it was just condensation, but I accidentally put my arm by it, and got sprinkled with black spots, seeming to be oil.

Is this possible?! It seems a long way for oil to travel. If so, what does this mean?! The performance seems fine, and nothing sounds bad enginewise.

I have noticed however, that I've been losing about a quart of oil between oil changes. It's not leaky out, because I would be able to tell...so it must be burning it. And it also seems that the oil gets pretty black too when I'm close to an oil change. As far as I know, the engine has ~70k miles on it.

Do all these factors lead to some conclusion. Again, performance wwise, everything seems good.

Thanks!

- Jeremy

 

[ICP777]

I'm thinking it could possibly be your exhaust valve seals. I would pull your exhaust manifold or headers off and look inside with a mirror. If there is any oil seeping from the seals you need to replace them.

Take it easy MATT

 

[zgator]

I had a 70Z/28 orignal LT1 engine that started doing that and my problem was a rich condition.Bought a new carb and all was good.I did keep the 780 that was on it and had it rebuilt.

 

[The73vetteman]

I'm thinking it could possibly be your exhaust valve seals.

I had bad valve stem seals, if that's what you mean. The big clue was that if I restarted the engine after it had sat for maybe twenty minutes there'd be a cloud of blue smoke out the back. Once that died down though, no smoke or mist.

My guess would be worn rings/bores but I suggest you run a compression test to find out.

John

 

[JohnZ]

If you get the "spots" when you start it up from sitting overnight, that's perfectly normal - just dirty condensate being blown out of the system. If you still get it after the exhaust system is heated up to operating temperature and blown out, it's probably running too rich or the choke isn't opening up all the way. If you have worn valve stem seals, you'll see blue smoke (not black spots) when you start it up in the morning and while you're driving when you let off the gas, then get back on it (high vacuum pulling oil down the stems, then it's burned). It's normal for the oil to get dirty as you approach a change interval - the detergent and dispersant additives in the oil keep dirt and combustion by-products suspended in the oil instead of letting them settle out and forming sludge.

 

[Ludigdrums]

Thanks everyone for your replies!

JohnZ - I feel much better about what you said. I think you're right because it only happens when I first start it up. After that, I don't get any smoke, except when driving and I floor it.

I also have the feeling that I'm running to rich though. That means too much fuel right? Cause I also get a gas smell. It's hard to determine if it's just exhaust, because I have an exhaust leak at the header collector, which I replaced to no avail. I used the good gaskets with the metal in them, and I also applied a gasket maker to it to try and seal it better. I think it might need 2 gaskets (I'm not sure if that's kosher though)?

How can you tell how rich/lean you're running? I'm running a Holley Carb, and for the most part, I think it runs great. I'm a little afraid to start messing with it until I know more of what I'm doing.

Any suggestions?

Thanks again!

- Jeremy

 

[Bob Chadwick]

Jeremy,

Start with your idle circuits. Hook a vacuum gauge up to a vacuum circuit and adjust the idle mixture screws until you get the best vacuum. Be carefull if you you should close them all the way to not damage the seats by putting too much pressure on them.

Bob