Smoke on deceleration

Hey guys, just recently noticed that after a pull, when I let off I looked back and noticed some smoke in the rear view mirror during the pull its clean just after letting off this happened. It wasn't a crazy amount but enough that it made me pay attention to it.

I'm going to check for shaft play to see if there's an issue there. At Idle in almost sounds like the turbo has a chirp to it. But when I turn the car off it still sounds like its spinning freely as I can here the wheel spinning smoothly after the car is off.

Just curious if there's anything else I should check or should I also compression test it?

Is it a stock long block?

Built motor, pistons, rods, cams.

Def be thinking about oil being sucked past a seal with high vacuum...valve stem seals.

The turbo never sees vacuum but maybe the seal is leaking a little and you can’t see it under WOT.


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I'm thinking about doing a leak down just to be sure.

Could over filling the oil cause the same symptoms?

Overfilling would cause it all the time I'd think. Plus you'd need like 10 quarts to get to the point of overfilling. Do you know what rings and what gaps were used? I made the mistake of using gapless rings in my built engine. It would suck the oil past the valve seals on decel. I learned later on this was a common issue with the mod motors and gapless rings.

I'm not sure on the ring gaps, but the rings were the total seal ap steel.

I had the stainless steel in mine. If you're running the gapless top ring I'd lay odds that's your issue. One time on the dyno when it was decelerating it shot out a whole bunch of smoke. I think Malcolm had similar experiences when he ran the gapless rings. Next time around I'm going to stick with traditional style.

Thanks for the info, I haven't heard about this and it's always good to learn something new. It just simply surprised me to see some smoke after a pull.

Any resolve with this issue?


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If it has ball bearing turbo and if it has restricters on the return hoses, if they are to small it will smoke


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Hey sorry, I did a comp test and leak down, everything was good there the worst cylinder was 6% most were 2-4%. So I looked else where. What I think it ended up being was my catch can was too full, I left it open for 24hrs to completely drain it. Since I have done that, I've had no smoke after doing a pull.

Wow. Best case scenario. Good for you!

Ya I was pretty happy after I did the leak down test.