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tbaumann

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Joined
Jul 2, 2007
Hoping for help diagnosing some issues with my car smoking. It only seems to happen when deaccelerating. I noticed that it coincides with when my vacuum is above 20 for more than 5 seconds. It smells of oil so I don’t think it a head gasket. The oil on the stick looks ok. I also checked the radiator and no sign of oil. I am pretty sure it oil smoke. I don’t notice it when under boost or cruising.

The things I have looked at so far, I replaced the PCV valve and added a catch can. I added some stainless screening to the catch can input strainer. The can is working as it did have oil water and yuck. I emptied it and tried another test drive. Still smoking on deaccelerating (example I drop from OD to drive while going down a slight hill). I rechecked the can and it had only a small amount of stuff as it was only a short 10 mile drive.

An ideas on narrow this down or other things to check next
 
Engine been opened up?
Mileage is?
Check the intake manifold, by pulling the tb, and looking. {Sucking oil past the intake gasket}?
Pull the down pipe, and see what's in there.
Check turbo for brg play. Stock turbo may have scrammed.
Plugs look good?
Leak down and compression tests?
 
Engine been opened up?
Mileage is?
Check the intake manifold, by pulling the tb, and looking. {Sucking oil past the intake gasket}?
Pull the down pipe, and see what's in there.
Check turbo for brg play. Stock turbo may have scrammed.
Plugs look good?
Leak down and compression tests?

To my knowledge the engine has not been open up. Mileage is 55K (If that is legit and I don't have a reason to believe that it is not) .
There is not a power plate.
I just replaced the with a new aluminum one to accommodate the addition of vacuum brakes and it did seem oily by the vac. block.
I have not done a leak down test and the plugs are fairly new. I can pull them to see if any one of them have an oil issue.
I will pull the turbo DP side and let you know what I find. Time to start digging in deeper.
 
To my knowledge the engine has not been open up. Mileage is 55K (If that is legit and I don't have a reason to believe that it is not) .
There is not a power plate.
I just replaced the with a new aluminum one to accommodate the addition of vacuum brakes and it did seem oily by the vac. block.
I have not done a leak down test and the plugs are fairly new. I can pull them to see if any one of them have an oil issue.
I will pull the turbo DP side and let you know what I find. Time to start digging in deeper.

I think I foud my smoking issues - I did some various testing and here are the results. I tried a new PCV with the same result, I then bypassed the PCV to make sure I was not pulling oil up through it into the TB, I git the same smoking result with the PCV removed so I replaced it. I pluued the up pipe and noticed oil in the grooves of the coupling hose, so I used s bore scope to try to look into the intercooler. I could see oil on the fin and ithe bast that I can tell it appears to same some oil in the bottom, I then check the Turbo and I have shaft play, some side to side but more concerning was the in and out I am seeing 1/8" plus.
What I suspect is on deacceleration the vacuum of the engine would pull some oil past the compressor seal but once the vacuum dropped or if it went into boost it would seal back up and not smoke.
Does this sound logical ??
 
If you still have the original valve cover to turbo inlet breather hooked up, then (most likely) that's where your oil is coming from inside the intercooler. Of course, the compressor seal could be leaking but that would not cause the trail of smoke you describe when decelerating. The piping from the throttle body & intercooler leading back to the turbo does not have vacuum in it at all...only pressure so the engine can not be sucking oil from the turbo compressor seal. A faulty PCV valve can allow oil to be sucked in the intake on deceleration if it doesn't close off to a minimum when under high vacuum. Oil out of the tail pipe under high vacuum is usually caused by worn or stuck piston rings that can't seal properly anymore. Also, worn valve guides and seals on the intake side will also allow oil to be sucked into the cylinder. Exhaust seals are not under vacuum at all...only back pressure so they won't be putting oil in the exhaust during deceleration. The exhaust turbine seal on the turbo could be leaking and once you wind it up and get it good and hot, it could be burning the excess oil off the housing and smoking during deceleration. Intake gaskets & head gaskets could be sucking oil at high vacuum BUT if you have oil sucking in the intake or through a blown head gasket under high vacuum, then you'll have crank case pressure under boost that will blow oil out of your breathers. And on that note, a catch can is a band aid for leaking rings, gaskets and seals. If the engine is sealed properly, you shouldn't have oil blowing out of the engine.
 
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Hoping for help diagnosing some issues with my car smoking. It only seems to happen when deaccelerating. I noticed that it coincides with when my vacuum is above 20 for more than 5 seconds. It smells of oil so I don’t think it a head gasket. The oil on the stick looks ok. I also checked the radiator and no sign of oil. I am pretty sure it oil smoke. I don’t notice it when under boost or cruising.

The things I have looked at so far, I replaced the PCV valve and added a catch can. I added some stainless screening to the catch can input strainer. The can is working as it did have oil water and yuck. I emptied it and tried another test drive. Still smoking on deaccelerating (example I drop from OD to drive while going down a slight hill). I rechecked the can and it had only a small amount of stuff as it was only a short 10 mile drive.

An ideas on narrow this down or other things to check next
my thought is the turbo,if you have a friend that can lend you another turbo to swap out with and then see what happens,but from what your describing,turbo needs some attention.
 
Dynamic seal leaking on compressor section of turbo under high vacuum.
Rebuild or upgrade.
 
If you still have the original valve cover to turbo inlet breather hooked up, then (most likely) that's where your oil is coming from inside the intercooler. Of course, the compressor seal could be leaking but that would not cause the trail of smoke you describe when decelerating. The piping from the throttle body & intercooler leading back to the turbo does not have vacuum in it at all...only pressure so the engine can not be sucking oil from the turbo compressor seal. A faulty PCV valve can allow oil to be sucked in the intake on deceleration if it doesn't close off to a minimum when under high vacuum. Oil out of the tail pipe under high vacuum is usually caused by worn or stuck piston rings that can't seal properly anymore. Also, worn valve guides and seals on the intake side will also allow oil to be sucked into the cylinder. Exhaust seals are not under vacuum at all...only back pressure so they won't be putting oil in the exhaust during deceleration. The exhaust turbine seal on the turbo could be leaking and once you wind it up and get it good and hot, it could be burning the excess oil off the housing and smoking during deceleration. Intake gaskets & head gaskets could be sucking oil at high vacuum BUT if you have oil sucking in the intake or through a blown head gasket under high vacuum, then you'll have crank case pressure under boost that will blow oil out of your breathers. And on that note, a catch can is a band aid for leaking rings, gaskets and seals. If the engine is sealed properly, you shouldn't have oil blowing out of the engine.

The breather is blocked going to the turbo and replaced with a breather on the valve cover. Still has the oil filler on the driver side. I replace the PCV valve with PCV1138DL, the one recommended by Eric from TT. I also tried running with out a PCV and blocking the line and it still smoked. I guess it is possible that is was still pulling old oil from the intercooler. I also run a small catch can which will have a small amount of oil in it but not enough to account for the smoke.
I am still leaning toward the turbo because of the large amount of in/out shaft play (I will try to measure it). I will also pull the exhaust side of the turbo to see how it looks in the down pipe.
 
Question,
Why would a power plate have to do with engine smoking during decelerating?
because if you have oil getting into plenum it can build up on the back ledge of the power plate while cruising due to the engine angle and forward motion and may not have been enough oil to see as a smoke issue , but when you brake or decel the oil can roll off the plate and cause a smoke issue
 
because if you have oil getting into plenum it can build up on the back ledge of the power plate while cruising due to the engine angle and forward motion and may not have been enough oil to see as a smoke issue , but when you brake or decel the oil can roll off the plate and cause a smoke issue
I would imagine it has to be more then a drop of oil to accumulate to create that much smoke
good point, thanks
 
The latest findings. I pulled the exhaust side and it was sooty but oily. It did look wet when I looked past the turbine wheel on the exhaust side. I pulled the oil return line and it look good, no blockage. I tried to measure the in/out shaft play and the best I can tell is it is 3/32 to 1/18"
So I back to thinking its the turbo seals and I need to replace or rebuild
 
The latest findings. I pulled the exhaust side and it was sooty but oily. It did look wet when I looked past the turbine wheel on the exhaust side. I pulled the oil return line and it look good, no blockage. I tried to measure the in/out shaft play and the best I can tell is it is 3/32 to 1/18"
So I back to thinking its the turbo seals and I need to replace or rebuild
My bad. I missed the part where you said the turbo had about an 1/8th inch of in & out play. If that's the case the turbo is toast. It should have next to none. So winding the turbo up and getting the exhaust side really really hot, it was burning off the excess oil and that's what you are seeing on deceleration. Time for another turbo.
 
because if you have oil getting into plenum it can build up on the back ledge of the power plate while cruising due to the engine angle and forward motion and may not have been enough oil to see as a smoke issue , but when you brake or decel the oil can roll off the plate and cause a smoke issue

Ha,ha, what?????????
 
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