Situation: Car leaks oil. 30% of the time if I boost hard under load (on-ramp, low rolling speed, etc.) I will see a fairly distinguishable ploom of blue/gray smoke exiting the rear of the car. I cannot determine whether this is oil dripping onto my exhaust pipe, or leaking from the turbo bearings into the exhaust port.

Given this situation, does anyone here have any thoughts or experience that might steer me in the right direction towards chasing away these gremlins?

Regards,
Carlos

 

I'd start by having someone follow behind you. If the smoke is coming out of the exhaust, then either the turbo oil seals are leaking, or the oil filler neck to engine block O-Rings are leaking. Remove and inspect one of the intercooler hard pipes. Also remove the rubber J-Boot between the Air Flow Meter and the inlet to the turbo. If you have oil in the IC pipes, but none in the J-Boot, then the turbo oil seals are leaking. If you have oil in the J-Boot, then the oil filler neck O-Rings are leaking.

Second, I'd give the engine a good cleaning with an engine degreaser (I use Gunk Engine Brite) and then watch for leaks. Obvious spots are the rear cam cover, oil cooler housing, and oil pressure sender.

 

Great feedback Cliff. Cleaning the engine first is definitely the best plan of attack at this point. There is oil everywhere.

Re: the oil filler neck - if that had leaky o-rings, wouldn't it cause oil to leak outside of the emissions system, and therefore I would NOT see smoke coming directly out of the exhaust pipe?

 

Yes and no. There will be some oil leakage from the lower O-Ring, but typically the amount of leakage is very small because the oil is not under pressure at this point.

The oil filler serves tripple duty as an oil mist seperator, oil filler, and scavenge point for combustion blow-by.

Look at the top of the mist seperator section and you should be able to see a rubber hose. This hose is routed to the intake J-Boot, just up stream of the throttle body

As the engine is running, air flow through the J-boot creates a low pressure condition or partial vacuum in the scavenge hose. If the O-Rings are leaking, this partial vacuum will draw air past the O-rings and will actually draw oil into the J-Boot. At idle this oil tends to collect or pool in the hose and in the J-boot.

When you "hit the loud peddle" the initial in-rush of air will have sufficient velocity to carry any oil that has pooled into the throttle body. From there the oil enters the intake and you get blue smoke out of the exhaust.