Just wanted to get some oppinions on this....especially from the guru's like kevin, ted, NZvert, etc...

My car is a 91 turbo. New turbo, rebuilt engine of unknown age.

Turbo makes good boost, spools quickly, no funny noises etc.

Engine starts and idles well. Holds 750 RPM for the most part. No starting issues.

Engine has good compression on all 6 faces 110-115 psi.

Car makes decent power 190 to the rear wheels at 7lbs of boost.

All the fuel and oil vapor emissions systems are stock, the purge valve is piped correctly and in good working order.

Here is the situation, the car has some symptoms of bad oil rings but not all of them.....

The car has moderate oil smoke when started after sitting for a week or more. A pretty good cloud comes out the tail pipes but clears up in 30-45sec. Then no smoke at high or low idle. Also the the car spewes huge clouds of oil smoke out the tail pipes when decelerating in gear above 5500 rpms (high vac). It takes a couple sec for it to start after I let off at redline and mostly clears up by the time it drops to 3500rpm or so but it seems to do it more and more consistantly. It does this regardless of if the oil is at the top or the bottom mark on the dipstick.

The wierd part is the car almost never smokes on shifts (only high RPM shifts when it hasnt been warmed up for at least 20mins or so). Further, if i hold a constant RPM, ANY RPM, in neutral, it does not even smoke a little bit, none at all. No smoke under redline WOT runs either.

Also even though the condition seems to be getting slowly worse as i put miles on the odometer, the longer I drive the car in one trip the better it gets. Less smoke the longer the trip is.

So is this the very early stages of oil control ring failure?

 

So when its cold? is that what this is getting at?

Im sure you're aware that reving the bag off it cold isn't a good idea.


Anyways - I would pull the TID and check the shaft play, and also inspect the inside of the I/C coupler at the turbo for any oil inside it.

I believe you've hit the nail on the head and your turbo oil seals are letting go....but I'd check out shaft play and look for oil content in the intercooler piping by the turbo to confirm this.

At the very least, doing these inpections will rule out one possible cause.

 

My suspicion is the oil control rings in the engine because the turbo is almost new from mazda, although I am hoping it's the turbo.

The inside of the intercooler and associated piping is clean, i checked that first.

As far as cold, it only takes the car 5-10min to come up to temperature. I dont drive it hard before that. Once it is at temp and has been for 5-10 min i drive it hard and that is when it smokes but the longer the car is at temp the less it smokes.

 

hmm it does sound like oil control rings to me....

i wouldnt worry too much yet it can take a long time for the rings to go all the way bad, or well to the point where the smoke is unbearable, or all the time...

 

What about shaft play?

Im assuming since you didn't mention it that there wasn't any....

 

Im gonna have to check it, but there was none when i installed the turbo because it was brand new. That was less than 2000 miles ago.

Plus there is ALOT of smoke on high RPM decel. Like people driving behind me cant see anything.

But it stops as abruptly as it starts.

 

Did you check other threads?

20-second high idle test
This usually nails the oil control rings.
Rev engine in neutral for about 20 seconds at least 4kRPM.
If the exhaust starts to smoke, it's the oil control rings most likely.
Check spark plugs - if they are significantly crusty and wet, it can be oil control o-rings or turbo compressor seal failure - check turbo test below.

Only other culprit is turbo - might be better to check this first...
Pull IC hoses - do you see lots of oil?
If it's easy to do, pull the IC - do you see oil dripping inside?

If the spark plugs look clean, then the turbo is spitting oil out the turbine compression ring.
Never assume the turbo is in good shape, even brand new or newly rebuilt.


-Ted