Blue smoke on cold start up

Tiny
DECKER24
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 111,000 MILES
Z71 4x4 5.3 v8 ex cab. When I start it up in the mornings I get a small amount of blue smoke coming out of the exhaust. It only last for a few seconds and goes away. I use mobile 1 synthetic 5/30 oil. Change oil every 5000 miles. Could this be a valve seal, pcv valve or what? Thanks ken
Wednesday, October 23rd, 2013 AT 2:17 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Hardened valve guide seals are the logical suspect if the smoking stops very quickly. Oil runs down the valve stems into the combustion chambers when you stop the engine. That can be aggravated by excessive gas in the oil from a previous running problem. That will clear up once all the gas has vaporized and been drawn out.

Your engine really isn't old enough or has enough miles for this to occur yet but that is the only thing that will cause smoke only at start-up.
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Thursday, October 24th, 2013 AT 5:40 AM

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