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Old 03-12-2008, 03:31 PM
Join Date: Mar 2008
Posts: 6
Default Bluish-White smoke on startup?

I bought a used 2004 Ext Cab Silverado with 78,XXX miles on it. Ive noticed that if the vehicle sits overnight, or for a few hours, I get a cloud of bluish white smoke out of the exhaust for about 20 seconds, then it goes away. I'm not losing any pressure and my truck isn't overheating. Everything runs fine. Any ideas? I'm thinking it's probably bad valves.
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Old 03-12-2008, 04:11 PM
Join Date: Feb 2008
Posts: 56
Default RE: Bluish-White smoke on startup?

it very well could be the valves, blue/white smoke is an indication that the motor is burning oil along with the fuel. im not 100% sure if it would be the valves though, maybe someone else here could shed more light on this problem?
2007 NBS Silverado, 5.3 V8 LT, 4x4 Z71, S&B Cold Air Intake, Flowmaster original 40 series single in dual out the rear w/ chrome tips, Airaid Throttle Body Spacer, Line-X Spray in bed liner, 7000K headlights
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Old 03-12-2008, 04:36 PM
Join Date: Aug 2006
Posts: 2,424
Default RE: Bluish-White smoke on startup?

Usually this is caused by oil seeping past the valve guides.
The repair involves having the either new guides and seals installed or having the old guides knurled and new seals.
However, if the engine is running fine otherwise and not consuming oil then there is no pressing reason to do anyhting about it.
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Old 03-12-2008, 05:32 PM
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Default RE: Bluish-White smoke on startup?

Viperx15, welcome to the forum!!!
'95 1500 Silverado, 350, flowmaster Force II exhuast, S&B CAI.

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Old 03-19-2008, 02:32 PM
Join Date: Mar 2008
Posts: 6
Default RE: Bluish-White smoke on startup?

I just changed out my oil with Mobil full synthetic 10W-30 oil. Chevy says to run 5W-30 but that doesn't work so well here in Texas. The smoking on startup stopped, but now my engine temperature is at 235 instead of the normal 210. I dont know if they are linked?
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Old 03-19-2008, 04:54 PM
Join Date: Mar 2008
Posts: 137
Default RE: Bluish-White smoke on startup?

I bet that the smoking will come back.Its just a matter of time until the oil makes its way back into the cylindar

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Old 03-20-2008, 01:50 AM
CF Junior Member
Join Date: Jun 2007
Posts: 72
Default RE: Bluish-White smoke on startup?

the oil weight and engine temp should not be linked at all, unless somehow the motor is working harder, but ive never seen that
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Old 03-22-2008, 01:08 PM
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Join Date: Feb 2008
Posts: 121
Default RE: Bluish-White smoke on startup?


I am afraid there is more to the story and it is going to show itself in the near future.

Changing to the synthetic oil, if anything should have made the truck run cooler.

I would put a new thermostat on truck and flush coolant system as you do not know the maintenance history of the truck. Need to get that temp down.

Of course, Ilike to install direct connect mechanical gauges to a vehicle: oil, coolant and amp. That way you know for sure what is happening out there under the hood.

Loss of oil pressure is the fastest way to lose a motor, overheating is the second fastest way to lose a motor.

Good luck in finding out what wrong with truck,
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Old 03-23-2008, 04:11 PM
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Posts: 435
Default RE: Bluish-White smoke on startup?

white smoke on startup is coolant burning, blue or grey - oil. have no idea which is more in your case.
in my opinion, and what do i know, your head gasket ain't quite right. look for outside leaks, maybe you'll spot some to know which side is it, but should you decide to fix it, replace both for the hack of being "there" anyway.
my prognosis is like this: you may end up with 1. bad spark plugs due to buildup on them (btw, pull plugs out and inspect them,
one/-s that have buildup on them, or oil residue on the stem will point towards bad side); 2 engine oveheating. if it sips in, it'll sip out through the same pinhole. resulting in exhaust gas sipping into coolant, boiling it at some point. had that on my buick century - coolant start looking like beer foam in the radiator.
also, you can do pressure testing and leak testing with contrast die. if you have extra cash on hand to spend.

goofy as it may sound, under the circumstance that i am wrong on premise 1, you can have condensate inthe engine forming overnight. it is supposed to be, but is not, truly sealed inclosure. moisture in air, moisture in gas, buildup on valve seats can create microscopic pores for moisture to sip in and condensate inside on the head/cylinder walls. another area for condensate to form is valve cover.

which ever way it goes, something's getting inside your combustion chambers, and if it burns white - it's coolant or whater, blue or grey - it's oil. or both. but if it sips in on cold and does not on hot - metal reenforcement iinserts in head gasket will do this, as metal shrinks as it cools - so hole opens, and closes as metal heats up/expends.

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Old 03-24-2008, 04:24 PM
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Join Date: Jan 2008
Posts: 371
Default RE: Bluish-White smoke on startup?

Thats a wierd one, a 25 degree difference in engine temperature from an oil change??? The smoke at start up is like ZX said-your valve guide seals. I used to change them all the time on my older cars with older enginesand the problem would go away. But the temp change and no more smoke is confusing, like ukr said you may have a coolant issue also.
Before you try to fix everything I would just keep a close eye on your oil and coolant levels. If one goes down start looking in that direction.
01 Silverado 5.3L 4X4
01 Camaro SS LS1 SLP
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