99 QCSB 4x4 5.9 litre, on the odd start up I get a little bit of smoke out the exhaust, It isn't smoke as in anyone else cant see but a tiny bit of vapor? Oil is clean , coolant is fine. 02 sensor is a mess and I think that cat is not to far behind as it has a rattle now. I have not looked but I would a assume the plenum is toast because they all are and that combined with the cat and the 02 points to plenum. So is it possible that this tiny bit of smoke is due to the plenum??????

 

Yep. Or valve seals. Have a look at the plenum though, it is pretty much a guaranteed failure point on these trucks.

 

yah i am sure withought even looking that the plenum is dinked I just wanted to confirm that a lil smoke in the exhaust is in fact a symptom or can be a symptom of the plenum.....

 

Depends on the color. Black smoke = running rich/unbearnt fuel.

White, sweet smelling smoke is coolant (could mean cracked cylinder head or blown head gasket)

Blue looking smoke means burning oil.