Blue smoke when accelerating?

smoke

#1

I own a Lancer Evolution X and I’ve been having a strange issue wherewhen accelerating around 2500-3500 rpm a thick cloud of blueish smoke starts pouring from the exhaust for about a second or two accompanied by a loss in power. The smoke stops quickly and then it runs like normal. This only happens once in a while for a second or two. When idling there is no smoke. Or at Wot. There is no coolant mixing with oil. The oil was recently changed with the proper oil. and it still happens once in a while. I checked the turbo and there is no shaft play or oil inside of it. There is no loss of boost. Although I did see a tiny pool of oil near the turbo inlet and some more oil coating the inside of the intake pipe. is it possible that the turbo just sucks up some oil that collects at the end of the intake? the PCV line which connects to the intake appears to be letting some oil into the intake.


#2

This sounds like you have worn valve guides and oil is leaking in to the cylinder.


#3

That has always been the weakness of turbos. With age, the seals on the shaft between the impellar being spun by the hot exhaust and the impellar pushing air into the intake begin to allow the oil lubricating the bearings to be drawn into the induction system. The exhaust side is under pressure, and the induction side is under vacuum, the assemblage is being heated by the exhaust stream and it’s spinning at high speed.


#4

wouldn’t valve guides smoke more often and at startup? And I checked the turbo and it was dry inside.


#5

Maybe it would be a good idea to run a dry/wet compression test and/or a leakdown test and see if there’s a piston ring problem.


#6

ASiemers, the answer to your question is “yup”. If it were smoking upon startup, that would be my suggestion.

If the valve stem seals were worn, oil from the valvetrain would seep past them when the engine was sitting overnight and sit on the backs of the valves, or in the cylinder if the valve is open. That burns off when the engine is again started. It actually gets drawn into the cylinders while you’re driving when you decelerate and the vacuum in the cylinders spikes, but it usually gets distributed in the air too thinly to see… unless it’s extreme. And yup, I’ve seen it so extreme that when decelerating a huge blue cloud follows the car down the road.


#7

Blue smoke when you lift you foot off the gas pedal is a sure sign of worn valve guides; not blue smoke on acceleration.


#8

The loss of power points to the turbo. All turbo’s have a waste gate to control boost pressure, specifically over boost. Oil is collecting in the waste gate plumbing and then pushed into the cylinders when the waste gate either opens or closes.

Time to pull the turbo and rebuild it.