Need some pointers to look at

[Jerome Leberer]

Hey guys and gals,

Long time creeper, first time poster. I currently have a 2011 silverado 1500, with 163,622 miles on it. It's a 5.3 vortec engine. It smokes from the exhaust a light blue exhaust that's mixed with a grey/white exhaust. It stops smoking after roughly 10 seconds of running. Haven't noticed it while driving. It also doesn't smoke every start-up. It rough idles when in park. I replaced the plugs and wires a couple weeks ago, and I started misfiring on cylinder 8 after the change, before the change it was cylinder 5. The only codes it's thrown is for the misfiring. I also pulled plug 8 after the codes to check it and found oil on it. I did a combustion gas leak test and the liquid stayed the same color (blue). I'm starting to lose my mind. Any thoughts, suggestions to try? Also, as of now....I've noticed no loss in power at the moment.

[swathdiver]

46 minutes ago, Jerome Leberer said:

Hey guys and gals,

Long time creeper, first time poster. I currently have a 2011 silverado 1500, with 163,622 miles on it. It's a 5.3 vortec engine. It smokes from the exhaust a light blue exhaust that's mixed with a grey/white exhaust. It stops smoking after roughly 10 seconds of running. Haven't noticed it while driving. It also doesn't smoke every start-up. It rough idles when in park. I replaced the plugs and wires a couple weeks ago, and I started misfiring on cylinder 8 after the change, before the change it was cylinder 5. The only codes it's thrown is for the misfiring. I also pulled plug 8 after the codes to check it and found oil on it. I did a combustion gas leak test and the liquid stayed the same color (blue). I'm starting to lose my mind. Any thoughts, suggestions to try? Also, as of now....I've noticed no loss in power at the moment.

You may have more than one issue going on.  Burning oil like that, I'd say it is time to rebuild the heads, new valve seats and this may cure your misfires as a valve may not be closing.  You might also have a broken valve spring on number eight as well.  Could also be a bad lifter.  Seems like a good candidate for a top end refresh if the oil pressure is still good.

[CamGTP]

Valve seals or a piston ring issue if it's cylinder 8 (passenger side rear by the firewall) is my guess.

 

You normally don't see non DoD lifter failures.

[Black02Silverado]

This might not make sense but my 2002 Silverado would puff smoke on start up but only after I towed my trailer up the interstate.  Didn't do it any other time.  It was confusing to say the least.  I had a small oil leak and in the process of finding it the smoke on start up stopped.  What seemed to fix it and this didn't make any sense is when I changed out the intake and plenum cover gaskets along with the oil pressure switch.  Change the switch out because it was really wet around it and was easy to get to with the intake off.

 

I know that this doesn't make sense but for me it worked for some reason.  Mine was also at 180k miles when I did all this.

 

I did more gasket changes to find the leak but that is another story to tell at a different time.