Heavy smoke on decel

[KwS]

Hi

My new VR4 has developed an issue since i test drove it.

Basically, on deceleration it smoke heavily. Smoke is blue, definitely oil smoke. Sometimes can smell faint burning oil smell from exhaust on idle but cant see smoke. Doesnt smoke when revved when stopped and doesnt appear to smoke at high RPM with or without boost. No smoke on boost. No smoke on cold or hot start. No whining from the turbos.

Shove clutch in, and roll into and intersection and 9/10 times its fine. decel into an intersection and itll pump a cloud of smoke that makes my car look like its on fire.

Owner swears it didnt do it when she owned it, and i didnt notice it on the test drive (although i think i smelt it once).

Ive read this could be turbos, rings, valve seals or PCV. Im going to rip PCV out and clean/check its operation, and im working on getting a small catch can.

How can i see if its the turbos, rings and valve seals?

Tempted to just get a replacement short block and some new turbos and be done with it

[Ryan]

It could be the turbo seals, especially in your high mileage example. My old car would do the same thing, especially on downhills. Perhaps examine the internals of your turbo piping, especially the rear one and see how much oil is contained within?

[KwS]

It could be the turbo seals, especially in your high mileage example. My old car would do the same thing, especially on downhills. Perhaps examine the internals of your turbo piping, especially the rear one and see how much oil is contained within?

Would there be any way to tell oil coming from the turbo seals, against oil coming in from the rocker cover breather?

Engine braking down hill is hilarious, like a damn James Bond car or something. People back way off. Kinda embarrassing for such a nice car though.

[Nick Mann]

If I were a gambling man I would put a lot of money on one of your turbo seals. Take your y pipe off and see if one pipe has more oil in than the other.

[KwS]

just had a quick nosy, the Y pipe is easy to get off so ill do that after work tomorrow. Just had a quick look too, and pulled the breather pipe off from behind the AFM (goes from rocker cover to intake before turbos), and it was dry as a bone.... no trace of oil at all (no sludge, nothing, just clean). Is that normal, or could it be blocked? Ill take the intake off and remove that hose properly and see if its blocked, but i wouldnt think so, its got a pretty large ID.

[KwS]

Oh, also removed the bung that blocks up the BOV return the other day (as it has an SSQV BOV). only 2-3 drops of oil came out, so there doesnt appear to be much oil pre-turbo.

[Spirit]

Where the Y pipe goes to the rear turbo take a look as have often seen oil collect there too.

[mike74]

Sounds exactly how my Pulsar went just recently. It would puff a bit of smoke out while changing gears or a bit when decelerating. After a couple of weeks like this it really went downhill FAST. New tubbie cured it straight away...bang went my respray fund
Before I changed the turbo, I pulled the inlet tube off it & gave the impellor a wiggle about to check for play. Radially it was ok but axially there was about 1/4" movement! If you can get in about to the turbo's easily enough, you could do a similar check to see if there's any 'slop' in the shaft...hope its an easy fix anyway, good luck

[KwS]

okay. removed Y pipe, very little oil (a thin coating all over the inside, but it wasnt "fresh" oil, seems like normal blowby to me), basically nothing on the inside of the front turbo housing, and almost nothing in the rear housing. The rubber hose from the rear turbo to the y pipe had a little oil pooling in it, but it was so little it just wiped away easily and no more was to be seen.

The post intercooler pipes are also almost dry, and the throttlebody is damn near spotless. There is by far not enough oil there to make me think its the turbos.

I did discover the PCV rattles, and if i blow into it, itll freely flow air both ways. That will need to be replaced asap, but would that cause me issue?

[KwS]

tried again. Blowing hard into the hose side of the PCV valve locks it up and seals off the air.

With the engine running at idle, if i pull the valve out of the valve cover, and put my finger over the end of the valve, its sucking with enough force to damn near suck the skin off my finger.

My theory is that on decel, really high vacuum, its sucking oil fumes, and probably straight oil out of the rocker cover, into the intake manifold.... hence bypassing all the piping and the throttlebody (thats why its got no oil on it).

Possible, or just desperate for a solution? lol

[thfelipeth]

sounds like turbo seals to me.. had the same issue for a while.. it would do it sometimes. it only gets worse... like you say while descelerating it would puff alot of smoke. itll start to smoke on idle.. wont be noticeable while driving or revving.. i ended up getting a new engine and manual conversion yay!! but money out the window

[elnevio]

Is this a potential valve stem seals issue?

[KwS]

I'm not getting any smoke on startup, which is a usual sign of bad stem seals. It only smokes on decel.

Really starting to bother me now, not know what it is. Turbos are cheapish to replace, but don't want to do that unless I know it's a turbo.

[Nick Mann]

I've changed tubs on 3 cars that had these symptoms and in all 3 cases the smoking stopped. I can't tell you that your issue is the same, I can only tell you my experience and that my guess is based on that.

[KwS]

I've changed tubs on 3 cars that had these symptoms and in all 3 cases the smoking stopped. I can't tell you that your issue is the same, I can only tell you my experience and that my guess is based on that.

I appreciate your advice. How did you narrow down which turbo was the failed one? Or did you just replace them in pairs?

Im still hoping like heck its the turbos, as they are much cheaper and easier to replace than the whole engine.

Either later today or tomorrow morning im going to whip the inlet off the turbos and see how much shaft play there is. Im hoping for some play in one of them (preferably the front one lol).

[Nick Mann]

I changed them in pairs on all three. On two cars there was more oil in the rear pipe to the Y and the other in the front pipe. There is a very small amount of shaft movement on perfect turbos, but the play along the length of the shaft seems to increase to allow the oil seal failure. Given time the play becomes apparent in the other direction too, in the worst one I have seen it allows the inlet turbine to wear on the housing.