Smoke Cloud From Exhaust
Thread Starter
4th Gear
Joined: Mar 2018
Posts: 4
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Smoke Cloud From Exhaust
Hey guys,
Thinking of buying a C4 next week, and I've heard of the issue of a smoke cloud coming out of the exhaust upon starting the car after it's been sitting for a few hours and lasting for 30 seconds or so. Anyone experienced this, and if so is it a major problem?
Thanks
Thinking of buying a C4 next week, and I've heard of the issue of a smoke cloud coming out of the exhaust upon starting the car after it's been sitting for a few hours and lasting for 30 seconds or so. Anyone experienced this, and if so is it a major problem?
Thanks
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
White most likely condensation no worries. But make sure cooling system isn't losing coolant.
Blue valve seals and/or guides worn.
Black over fuel leaking injector(s) or FPR. Sensor skewd.
Blue valve seals and/or guides worn.
Black over fuel leaking injector(s) or FPR. Sensor skewd.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
First I would not say smoking exhaust is common for C4 Corvettes.
Condensation/steam from the exhaust is normal and nearly every car does this on cold mornings. This is not smoke and it usually disappears within a few minutes. It sounds like this is what your car is doing -- if everything else works fine and the car runs good, I would not worry about it.
But Kevova is right that steam can also be caused by bad head gasket - coolant entering the combustion chamber (loss of coolant).
If you are talking about actual white smoke (not steam) that happens only on startup, again Kevova is right that it's valve guides or valve guide seals. This usually happens on motors with high-mileage or have excess wear for some reason (abuse, lack of maintenance, etc). If it's really smoke and it happens all the time, that's probably worn piston rings.
Black smoke is caused by excess fuel or heavy detonation (during acceleration).
Condensation/steam from the exhaust is normal and nearly every car does this on cold mornings. This is not smoke and it usually disappears within a few minutes. It sounds like this is what your car is doing -- if everything else works fine and the car runs good, I would not worry about it.
But Kevova is right that steam can also be caused by bad head gasket - coolant entering the combustion chamber (loss of coolant).
If you are talking about actual white smoke (not steam) that happens only on startup, again Kevova is right that it's valve guides or valve guide seals. This usually happens on motors with high-mileage or have excess wear for some reason (abuse, lack of maintenance, etc). If it's really smoke and it happens all the time, that's probably worn piston rings.
Black smoke is caused by excess fuel or heavy detonation (during acceleration).
Last edited by DGXR; Mar 6, 2018 at 12:20 PM.
