smoke coming from tailpipe

[bulldogs27]

i have a 92 gmc jimmy with a v-6 vortec engine...when the car has been sitting cold for a substantial amount of time, it releases a puff of white smoke when the engine is started...i've noticed it doesn't do that when the engine is fairly warm...any ideas as to what that might be?

[clariveros]

The main emissions of a car engine are: Nitrogen gas (N2), Carbon dioxide (CO2), Water vapor (H2O) A product of combustion. The hydrogen in the fuel bonds with the oxygen in the air. there by creating water in your tail pipe you usually notice it when you start the car because the vapor cooled inside the tailpipe when the car was not running and the water collected inside so when you turn on you car in it heat up the water that collected and you get the white smoke (steam)

[bulldogs27]

so this isn't something i should be worried about?

[clariveros]

If it worries you when the car is cold and you go to turn it on take a piece of cloth or a sheet of paper and hold it by the exhaust pipe if it gets wet, then i would think that there is no problem, Also look at other cars on cold mornings many do the same thing, but keep checking the posts, in case someone else might post some different opinion.

[BlazerLT]

It is condensation in your exhaust system.

Completely normal.

[flywings85]

Is it an oily type smoke, other than steam?

If so, I may know what you're talking about. While my 98 Jimmy does not have this problem, a relative of mine's old 1990 GMC Suburban did. Everytime he would start it while cold, a puff of oil smoke would be released. From then on, while the engine was warm, no smoke was released upon ignition.

He was relatively mechanically oriented, and knew a pretty good deal about automotive engines. He said that just a tiny bit of oil seeped into the cylinders after sitting for a while, and it was no big deal, it didn't hinder engine performance whatsoever.

If you want to have the problem fixed, I would imagine it is fixable, but for now, I don't think you have much to worry about.

[blazes9395]

Valve guide stem seals. That is what is causing the problem. The seals are hardening and not sealing. Flywings has it just about right. Oil does get past the seals and get into the combustion chamber. Just at startup there is a puff of white smoke and then its gone. It won't hurt the engine or performance for that matter, it just doesn't look that great - especially if its coming from a relativily new truck. The parts are cheap, around $50.00 for the replacement kit from GM, but the task of removing the old ones and installing the new ones is quite labour intensive.

[BlazerLT]

Originally Posted by blazes9395

Valve guide stem seals. That is what is causing the problem. The seals are hardening and not sealing. Flywings has it just about right. Oil does get past the seals and get into the combustion chamber. Just at startup there is a puff of white smoke and then its gone. It won't hurt the engine or performance for that matter, it just doesn't look that great - especially if its coming from a relativily new truck. The parts are cheap, around $50.00 for the replacement kit from GM, but the task of removing the old ones and installing the new ones is quite labour intensive.

White smoke does not come from oil. White smoke at startup comes from condensation or antifreeze.

If it was oil, the puff would be blue.

Mine does the same thing at startup. Until is warms up in the cold, it is white water vapour until the exhaust system has warmed up enough to expell all moisture from the headers to the tailpipe.

Nothing is needed, everything is absolutely fine.

His engine is perfectly normal.

[blazes9395]

Yes correct, nothing is really wrong. And yes let my correct myself, white/blue smoke. But if its only at startup and its white/blue smoke..it is valve guide stem seals. Easy way to tell is if the "puff" does not evaporate and it lingers its smoke. I have owned four blazers with the 4.3, and I have always had this problem. I changed the seals myself every time and it always corrected that problem. The most recent one I have done has been my 93 with the 4.3 W engine. On the other hand if it IS anitfreeze burning when started, that would be a problem. Antifreeze getting into the engine is BAD, casues many problems, just ask fellow GM owners who have had the poorly designed intake gaskets on their cars, vans, and trucks....

[BlazerLT]

But he is only having minor white condensation smoke which is completely normal for all cars.

My spews white water vapour when it is warming up.

[goinbig]

Yes, I think just about every single car in the world will do this.