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bluish white smoke from tailpipe - '06 4.8 vortec
06-16-2012, 01:21 PM
Post: #1
bluish white smoke from tailpipe - '06 4.8 vortec
My brother-in-law and myself are trying to determine whats causing his '06 silverado 4.8 to blow bluish/white smoke out the tailpipe when driving.

A little background...

we've done a few oil changes in the last couple of weeks and after the oil change, the dipstick shows full and a few days later, the truck all of a sudden starts to blow smoke out the tail pipe while driving. Re-checking the oil level comes back with a dry dipstick. Oil pressure the whole time is being displayed via the dash as having 40 pounds of pressure.

We ripped off the intake this morning to find that it was full of oil. We had a thought that it might not be correctly draining and pulled the lifter valley cover off to find no excessive oil in the top of the block.

Apparently, there is no PCV valve in this motor, so replacing that is out of the question.

truck has approximately 200,000 miles on it also.

Anyone run into this or have any ideas on where to look next? We're concerned that the dipstick showing dry even though the dash is reporting good oil pressure may cause long term problems for the motor.
More importantly, how is the oil getting into the intake with enough volume to cause this smoking?
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06-16-2012, 04:26 PM
Post: #2
RE: bluish white smoke from tailpipe - '06 4.8 vortec
my guess, head gasket letting oil in chamber and what is not burning is getting pulled by the EGR into the intake




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06-16-2012, 10:42 PM
Post: #3
RE: bluish white smoke from tailpipe - '06 4.8 vortec
Sounds like the intake gasket is bad.

When the engine gets low on oil, the oil preasure goes up. It's not a volumn meter, it's a preasure meter. It's still pickin up oil even though it's below the dip stick level.
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06-17-2012, 05:42 AM
Post: #4
RE: bluish white smoke from tailpipe - '06 4.8 vortec
(06-16-2012 10:42 PM)Tango Wrote:  Sounds like the intake gasket is bad.

When the engine gets low on oil, the oil preasure goes up. It's not a volumn meter, it's a preasure meter. It's still pickin up oil even though it's below the dip stick level.

When we pulled the intake off, we didn't see any signs of oil around the intake ports on the head; the gasket "appears" to not have been leaking.

We'll look into this a little more.
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06-17-2012, 06:52 AM (This post was last modified: 06-17-2012 06:52 AM by JasonB.)
Post: #5
RE: bluish white smoke from tailpipe - '06 4.8 vortec
have you checked the compression? you could be blowing oil past the rings, then like bad head gasket sucking oil through the egr into the intake




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06-17-2012, 09:53 AM
Post: #6
RE: bluish white smoke from tailpipe - '06 4.8 vortec
We haven't checked compression yet but upon further investigation, it looks like the intake gasket around one cylinder had a bit more oil then the others and the spark plug for that cylinder was in worse shape then the others.

We've got it put back together now (can't do a compression test without it together) with a new intake gasket and we'll see how we do.

Thanks for the responses; crossing fingers that the new intake gasket fixes the issue.
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06-17-2012, 10:16 AM
Post: #7
RE: bluish white smoke from tailpipe - '06 4.8 vortec
I would do a compression test just to be sure it's not blowing past the rings, but it sounds as thought you may have the problem solved Big Grin
Scott
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06-17-2012, 01:16 PM (This post was last modified: 06-17-2012 01:18 PM by Tango.)
Post: #8
RE: bluish white smoke from tailpipe - '06 4.8 vortec
Another way for oil to get in there is intake valve guides leaking, but the intake gasket is the most likely issue.
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06-18-2012, 04:54 PM
Post: #9
RE: bluish white smoke from tailpipe - '06 4.8 vortec
update.....

We replaced the intake gaskets and unfortunately, driving the truck down the street, smoke started to blow out the tailpipe.... grr!

Compression test results in numbers between 175-200 across all 8 cylinders.

We bought an new "updated" valve cover that is "supposed" to resolve some of the issues with the original valve covers but we don't want to put it on unless we know for sure it will fix the issue.

Any other ideas on where to look next before going down the road of replacing the valve cover?

Thanks everyone!
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06-18-2012, 05:38 PM
Post: #10
RE: bluish white smoke from tailpipe - '06 4.8 vortec
How does the engine breath .. and where does the oil vapor go without a PCV valve?

Do you have any other lines that could vacume the oil into the intake?

I think bad intake valve guide seals could also cause that and is likely with 200k on it.
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