Hey y’all. I got a 5.3 turbo that’s is burning oil and I can’t seem to figure out why. The engine has forged rods and pistons, cam, ported heads, and 90lbs injectors. It’s a 7675 Precision turbo and it’s paired with an oil catch can. Once I hit above 2500rmps, I start smelling oil and see a cloud of smoke. The piston rings are gapped at .024 top and .025 on the second one. For the fuel pump, I got a 525 walbro to push about 15lbs of boost. I’ve relocated the oil return line to make it quicker and it seem like it didn’t help. Any ideas? Thanks!

 

Are you set up with a check valve in the system, so you are not blowing boost back in the crankcase. When I first got mine running, it blew a lot of smoke, so I added a ck valve, small oil sep, then to the PVC valve, no smoke.

 

Probable crankcase pressure.

Proposed TEST:

Install 1/2" (inside diameter) OPEN VENT hose on driver side rocker cover.
Install OPEN 3/8" VENT hose on passenger rocker cover.
Go run heavy boost.... Is smoke GONE ?

 

What size is your turbo drain? does it have a good angle to drain? Pop off your down pipe and see if its covered in oil. Most don't go large enough on oil drains.

 

A -10an is usually sufficient but I've measured some china -10 that measures under .480. I've had great success with simple 3/4" barb ends and high temp oil hose. 99.9% of turbo smoke issues I've worked with are drain related.

 

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,WELL ? Crankcase pressure, or Drain line restriction ?

.......................................... Did you FIX it ?