I suspected a head gasket on my L33 in the Silverado due to some occasional smoke clouds from the exhaust. Upon tear down, I found chocolate milk under the valve covers and behind the timing cover.

After repairs plus some new parts, I'm having a few issues. I'm getting smoke on cold starts which typically continues all the way up to temp at idle. When I drive around the block, it goes away and stays away when I stop again and sit at idle. Hard for me to say if its white or blue honestly. Doesn't smell sweet.

The catch can that I installed at the same time has been filling up extremely quick, like almost full after driving less than 20 miles, its not straight oil but it is black. Thin consistency. Catch can is on driver side, valve cover to intake.

Oil on dipstick looks good. Drove 100 miles after repair, did an oil change, another 100 miles on it so far. Nice and clean, no milkiness on dipstick or when I changed the oil.

Otherwise the truck is driving well. Good oil pressure, 30-50 psi, running temp right at 210

Everything I did:
Pulled heads, home rebuild (first time), new seals, lapped valves, trunnion bushings, new LS6 style summit springs, GM LS1/6 gaskets
ARP head bolts
New lifters, Summit branded Morel style
New pushrods, BTR 11/32
New cam, Summit Torkinator SUM-8727 200/205 0.550
New AC Delco water pump and thermostat
Speed Engineering 1-3/4" long tubes and full dual exhaust kit
New Taylor Spark Plug wires
New plugs
Oil Catch can (driver side, valve cover to intake)
Replaced all gaskets
216k miles


So, the smoke from the exhaust plus the fast filling of the catch can, what could be going on here and what should my next steps be? I'm planning to pull a valve cover or both when I get some time. I realize I may have more than one issue. Worried I may have done valve seals wrong and they're leaking oil. And that I may still have a coolant leak, either head gasket or even a crack in the heads or block that I'm unaware of.

And the catch can has me confused. The old PCV tube doesn't have any oil in it that I can tell. The section of the new can line from the can to intake appeared to have light brown liquid but the section from can to valve cover was dry. I don't know where all the fluid is coming from.

 

The fluid is likely condensation. FWIW my 07 5.3l suburban chugged oil for many years and I just assumed the engine was worn. Similar symptoms to you, smoke on startup, lots of oil consumption on long drives, milky stuff under valve covers. I ended up changing the drivers side valve cover and it no longer has any of these issues. GM released an updated valve cover with a different pcv valve and this seems to have solved my issue.

 

Interesting. I have one of those valve covers on the engine in my garage for the Camaro so I’ll swap it on. I did recently learn the one on my truck isn’t the same and I don’t guess they’re a replaceable PCV.

Heres the fluid from my catch can. Seems like a water oil mix of some sort but my oil isn’t this dirty.

 

Could be your valve seals are leaking.

 

Condensation and when you're also driving it in cold weather there will be even more condensation. If unchecked it will get sucked into the intake manifold where it can wreak more havoc.

 

That's looking like a pretty normal, chocolate milkshake type color that I usually see.

 

Had a suburban that did exact same thing, replaced driver valve cover and it stopped completely.