Blue smoke at idle om617

[w123suv]

I have been trying to chase down this smoking issue for a couple months. It’s a friends car that was run very low on oil.
Compression test found 400 in all but one cylinder at 280. I assumed that was the cause of smoking. I got the compression back up to 400 and the smoking is still there.
I don’t know if it is valve stem seals? There is no smoke at startup.

Could it be an issue with the turbo leaking oil into the intake?

I need to troubleshoot this but do not know where to start?

[R-3350]

check your cam timing, and injectors those are the two most likely candidates. it could be a failing turbo oil seal but that would also show as excessive smoke at high rpm more than idle as with rpm the oil pressure increase would push more out the seal. does the smoke smell kind of sweet? or is it more like burning plastic? sweetish smoke tends to be uncombusted fuel while oil smells more like burning plastic. depending on exactly whats up they can both appear blue white. and finally what did you do to restore compression it may be that it has a burned valve or glazed rings and compression returned to the low value it was before causing the smoke.

[torsionbar]

Do a cylinder leakdown test, it will help tell you where the oil may be getting in from. Compression test won't. If this problem started right after the engine was run out of oil, I would pull it and do a simple rebuild without bothering with all the diagnosic time. You know what caused the problem, so you know all the usual wear items are probably toast.

[Diesel911]

Originally Posted by w123suv

I have been trying to chase down this smoking issue for a couple months. It’s a friends car that was run very low on oil.
Compression test found 400 in all but one cylinder at 280. I assumed that was the cause of smoking. I got the compression back up to 400 and the smoking is still there.
I don’t know if it is valve stem seals? There is no smoke at startup.

Could it be an issue with the turbo leaking oil into the intake?

I need to troubleshoot this but do not know where to start?

If this was happening if you pulled an Injector near where the turbo attaches to the Intake Manifold, remove the heat shield and look inside the Pre-combustion chamber will have a shiny wet sheen to it. The normal Pre-combustion Chamber Color is flat black.
It would be the same if Oil was getting past the rings and the Cylinder.

You did not say what you did to get the compression higher but if it was sticking rings it is possible the Oil rings are sticking.

If the exhaust side of the Turbo is leaking when you remove that wrinkled expansion piece of the Exhaust it will have that shiny black sheen and there will be a build of shiny carbon on the housing outlet and maybe even the Turbine Wheel.

[w123suv]

Originally Posted by R-3350

check your cam timing, and injectors those are the two most likely candidates. it could be a failing turbo oil seal but that would also show as excessive smoke at high rpm more than idle as with rpm the oil pressure increase would push more out the seal. does the smoke smell kind of sweet? or is it more like burning plastic? sweetish smoke tends to be uncombusted fuel while oil smells more like burning plastic. depending on exactly whats up they can both appear blue white. and finally what did you do to restore compression it may be that it has a burned valve or glazed rings and compression returned to the low value it was before causing the smoke.

I believe the timing is good. I did a new timing chain a few thousand miles ago and I just checked ip timing a couple days ago. I also replaced the fuel injectors at that time because they were pitted around the pintles?

I restored compression by rotating the valves to reseat them.

[w123suv]

Originally Posted by Diesel911

If this was happening if you pulled an Injector near where the turbo attaches to the Intake Manifold, remove the heat shield and look inside the Pre-combustion chamber will have a shiny wet sheen to it. The normal Pre-combustion Chamber Color is flat black.
It would be the same if Oil was getting past the rings and the Cylinder.

You did not say what you did to get the compression higher but if it was sticking rings it is possible the Oil rings are sticking.

If the exhaust side of the Turbo is leaking when you remove that wrinkled expansion piece of the Exhaust it will have that shiny black sheen and there will be a build of shiny carbon on the housing outlet and maybe even the Turbine Wheel.

Thanks for these diagnostic tips. As soon as I can I will check it out.

[w123suv]

One thing I noticed today is that after driving at temperature for 30 or more minutes when I come to a stop I will usually start to get the smoke. If I rev the engine I get a small cloud of smoke but then it stops smoking.

It never smokes at startup.