1998 Chevrolet Silverado smoke and oil leak

LANELEE5211

MEMBER
1998 CHEVROLET SILVERADO

I just got me a 1998 chevy 4x4 that someone took the 5.7 out of it and put a 400 small block in it but they also some how put the 5.7 intake on it and is flue injected when I start the truck white smoke comes out of tail pipe and when I give it gas some black smoke comes out and there is a light black fluid coming out of tail pipe but fills like waters and when I put it in gear it wants to die what could this be

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Do you know what year the 400 is? Also, you said they fuel injected it. Did they replace the heads?

As far as the smoke, white smoke usually indicates a bad head gasket or coolant getting into the combustion chamber. As far as the water in the exhaust, to an extent that is normal. Condinsation builds and comes out as water when the system gets hot. As far as the black you see in the water, most likely that is just some carbon from the exhaust.

Since things are changed (engine), it makes things difficult because I have no idea what has been done. However, I need you to check a couple things for me. First, check intake manifold vacuum. If there is a leak, it could be the problem. If the vacuum is around 17, then I would recommend moving to the fuel pump pressure to see if it is within the manufacturer's specs for the 5.7L. Also, let me know if the stalling is all the time and if it runs good once off an idle.

Do that first and let me know what you find.