I have a 1990 1500 4x4 4.3 v6. She just recently started smoking. Its very light. I changed the oil. Took it on a long drive. Still smoking. Oil level holding. I am hoping the motor is not burning oil. I was told I need a new catalytic converter to pass emissions. What may be causing my truck to smoke?

 

white smoke is oil...is it only at start up?

 

no it seems to be constant however it is very light. I can only see it at start up or when I pull off from a complete stop and sometimes if i am in gear and idling. I just changed the oil a day ago to see if that helps.

 

Leaky valves or rings probably. And catalytic converters go bad pretty quick when you are blowing smoke and crap through them.

 

i thought white smoke was coolant while blue smoke was oil. i didnt know when that happened to change...

 

My 89 GMC Sierra is blowing White smoke as well but the coolant levels are holding, its the oil that is going missing. We pulled the heads and noticed that the passenger side head had a decent sized gash in it that was allowing blowby. This may be the same issue you are experiencing. I would investigate the heads.

 

those 305s were notorious for bad valvetrain.

 

Acracked head is kind of a wild stab in the dark. It definitely happens and that could be the case but that is a rare occurance.

 

my case were 2 cracked pistons.... you wont know till you tear er down.

 

Water being burned in the cylinders wouldbe my guess.Usually leaking head gasket or cracked head. Only my guess because I had the exact same problem with these same out comes before.

A cracked head might be a wild stab in the dark, but as I found out, those wild stabs are sometimes worth it.