*Update, post #4. Problem found and solved.


Fairly new combo in my truck. LQ4, stock 24x crank, gen 4 rods and flat top pistons, 799 heads. BTR 660 springs with unknown LS valve seals someone gave to me (they don't look like the valve seals that BTR has since recommended to me), VSR 80/96 turbo, oil drain is free flowing and goes to front of oil pan without restriction. Tune is pretty good, on e85 fuel.

I get smoke coming from the tailpipe, light blue/grey color (oil) and it's at random when I come to a stop. Not on first start up, not at WOT, not while cruising, not during decel, just when I come to a complete stop after cruising it smokes out the tailpipe for several seconds and then stops. When I take back off, it doesn't smoke. When I give it some throttle while holding the brakes and keep rpm up to about 1200 as I come to a stop, it doesn't smoke. Cold starts, it doesn't smoke.

I don't thing it's a head gasket because it's not over heating, turbo seals aren't blown, I see no pooling of oil inside the turbo compressor or exhaust housing, cold side piping or inside the intake manifold. I'm thinking it's not the piston rings because I'd see smoke all the time especially at WOT and I'd have a decent amount of blow by (which I don't), right? I'm leaning towards one or more valve seals are jacked up slightly and as I go into high vacuum on decel with the throttle body closed, it's possibly pulling oil past the seals?

It wasn't doing any of this up until just recently. Thoughts?

 

Sounds like that unknown valve seals are leaking, and causing oil to puddle up on the valves and while your sitting at idle your seeing it burn off causing it to smoke. Someone else can chime in but if it were me id put the valve seals btr recommended.

 

Yeah I definitely think that’s the issue. I didn’t know they needed a specific seal to go with the springs until I emailed them the other day. Definitely going to swap them out with the correct seals.

 

Well, problem solved. I'll still change the valve seals to what BTR recommends. But my issue was right here. Clogged 10an hose that goes from the valve cover to the catch can, 100% blocked. Rubber in the hose broke down and collapsed on itself. Crankcase pressure was through the roof, pushing oil out of whatever seal it could, causing both tailpipe smoke and oil leaks onto my turbo crossover pipe. Good lesson for some to learn, always check your ventilation.

 

wow that wouldnt be one i would expect, at least you figured it out. Lucky it didn't blow the rear main. Good reason to weld an bungs on the valve covers and use AN lines.