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Small puff of smoke on start up

trueblue's Avatar
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September 20th, 2006, 3:35 AM   #1  
Small puff of smoke on start up

I have a 1992 S10 Blazer with the 4.3l vortec. It runs pretty good other than a tranny problem and a little miss. But on start up it puts out a white puff of smoke and then nothing else until it gets started back up after several hours. Does anybody know what this could be. I'm pretty new to Chevrolet's and I'm only a weekend mechanic. Any help would be appreciated.

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October 11th, 2006, 1:47 AM   #2  
RE: Small puff of smoke on start up

I have a 92 S10 pickup with the 4.3L. I have a small puff of smoke as well on start up after the truck has been sitting for awhile. It used to be when it sat overnight, but over the years has slowly gotten worse to where now if it just sits for 3 or 4 hours I will see some smoke on start up. I wouldn't say mine is white though, maybe kinda. I was told that the rings around the pistons are wearing out and while the engine sits, it's allowing oil to seap down below and when the engine starts, the oil is getting burned off. Whatever you have seeping is getting burned off when the engine is started. I havn't worried about mine much, as it doesn't seem to affect the performance of the engine. When it starts buring or smoking all the time or more than at start up, that's when you should worry. I'm just waiting until mine gets real bad and then I think I'll just go for a brand new engine. I think I started to notice a little smoke on start up when I still had somewhere in the 75K mile range. The truck is a 92, and I've had it since 95. Around 40K miles when I bought it and now I have 174K miles and I still would drive this truck anywhere, anytime. Best damn truck in my opinion. (Screw the Japs) Don't think this really helps your specific problem though, sorry, if your real worried about it though, try and find a good trust worthy mechanic to ask. (Just not the Chevy dealer as it seems the powers that be have given them a license to steal.)

golfer's Avatar
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October 11th, 2006, 2:34 AM   #3  
RE: Small puff of smoke on start up

On cold start:
white exhaust - moisture ( condensation ) should only last a short while this is normal
blue / white - oil burning could be valve seals if only shows for short time
dark or black smoke - too rich fuel

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October 11th, 2006, 12:21 PM   #4  
RE: Small puff of smoke on start up

The puff of white smoke on 4.3, 5.0 and 5.7 liter engines built in the late 80's thru the early 90's is caused by excessive clearance in the valve guides, normally the engines don't use much (if any) oil and it is not going to create any problems if you don't address the issue.
The fix is to either have the valve guides knurled or replaced.


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October 13th, 2006, 3:39 AM   #5  
RE: Small puff of smoke on start up

sorry guys, but usually white smoke is caused by a coolant leak-a leaking head gasket or a warpped head (or both!). trueblue, U failed 2 mention if the 'smoke' is light and transparent (moisture) OR is it thick and sweet smelling (like sugar, and coolant), and how long does the 'smoke' last 4?. also, did your truck overheat recently?, if it did pull the plugs after it has sat 4 a while and look 4 any water/condensation on the plugs. if U find some, it could be the problem(s) i mentioned above. altough i haven't heard of the clearance in the valve guides 2 B an issue, i routinly run my 308,000 kilometer 4.3L/5spd. powered '92 jimmy up 2 7grand (yes that's correct, and no the motor is stock) and run it at high rpm's/lower gears in traffic, and i've never seen any smoke out the tailpipe-except when the head gasket failed at the 292,000 mark (usually it's the left side, between cylinder's 3 and 5 that fails) IF the smoke was blue/grey at start-up, the valve seals R wearing out. if it puffs blue/grey all the time the rings are going- remember, the oil can only drain down (following gravity), so if the engine sits awhile (couple of hours/overnight) the oil drains down through the valve seals and sits on top of the piston, waiting for U 2 burn it off at the next start-up. try letting the truck idle a short while (30 secongs?) B4 shutting it down, this helps in my '90 Suburban-most of the time. good luck. (8p

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May 25th, 2017, 2:34 PM   #6  
hope this will help.

i cannot figure what the problem with my...
i cannot figure what the problem with my 2001 blazer ls 4.3l rwd is on start up the exhaust puts a sort of big puff of white smoke out after sitting for a couple of hours. i know i dont have problems with the oil rings and valves because i have done a pressure test on all 6 cylinders each cylinderhas 120+ psi so i dont have any compression loss but it seems to be putting out a white cloud only on start up after sitting for a few hours i was thinking it might be the intake gasket but im not sure. can you help me please?
25 May 2017 02:13

25 May 2017 02:17
Pete Pete
Chevy Mechanic
Hi my name is Pete and I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Intake gasket leaks are very common as the gaskets used were a poor design that shrunk or collapsed after several miles and causes oil and coolant to sometimes leak into a cylinder port.But the biggest issue with this smoke on start up is valve seals leaking.The valves may be sealed as per your pressure test but the seals can leak and allow oil to leak down in the valve cover past the seal onto the top of the valve.The more it sits usually the more smoke.Then on start up this oil is quickly burned off causing the smoke issue briefly.I have had to go through and replace the valve seals.Valve seals leaking will not affect compression or psi that a cylinder holds/leak down testing.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

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