Hello,

I have a '92 Dodge (w150). my truck runs fine...but when I start her up she puffs out a bit of blue smoke (I know that's oil, but from where?) after startup it's fine. sometimes I get a tad bit of black smoke, but not very noticealbe. what could be causing these?

Thanks,
Larry

 

Well, I can't speak for the trucks, as to common problems.
I know when the valve stem seals in my grandpa's 3.0L V6 in his minivan were going out, it would blow blue smoke upon start up, and than the smoke would go away. It only got worse after that (it would blow a big cloud of blue smoke at every stop sign, and burn about a quart of oil every 3 days).
A worn out engine (piston rings, etc.) could also cause this.

 

I agree.

Could be valve seals. Could be that the engine is getting a little loose (worn rings).

How many miles on the motor?

 

Typically it's the valve seals, and not worn rings, when it smokes at startup. Some of the oil in the heads will leak past the valves into the cyls and burn when you fire it up.

Black smoke would probably be a bad O2 sensor or stuck fuel injector or something else causing it to run really rich.