Smoke Out Exhaust

[Joel Russo]

Had the car out for a run yesterday, couldn't resist a sunny 45* day.  When I returned home, I pulled on the driveway...let it idle.... while I moved a few bicycles from in front of the GN stall door..


As I walked toward the car, I noticed "smoke" coming out of the exhaust.  Looked to be typical bluish in color and had the smell of burning oil.  I checked temp gauge and it was 165*, which is where it was while I was out for the run.  I blipped the throttle and the smoke briefly went away until in came back to idle rpm, and then it came out of the exhaust again.


I did not notice it while driving or stopping while I was out on the road, but then again, I wasn't looking for it.


Stock unopened '87 GN with 14k on the clock..


Do I need to replace valve seals, or do I have a issue somewhere else?

[Steve Wood]

That is a definite "maybe"

I would start by checking for oil in the pipe to the throttlebody from the intercooler in case the turbo seal is leaking.  Also I would like to assume you have replaced the tube from the end of the valve cover to the turbo inlet with a small KN filter plugged into the end of the valve cover and capped off the inlet to the turbo.  You might also check to see if the pcv valve rattles when you shake it up and down to be sure it is not stuck open.

You could also do a leak down check to make sure the rings are not worn out and you are sucking blow by thru the engine and out the exhaust.

[Joel Russo]

I have a small KN filter on the end of the valve cover, and capped the inlet to the turbo.


The PVC valve rattles when I shake it.


I removed the up pipe from the intercooler, and it was relatively dry.  I rubbed my finger in it to show that there is a bit of oil build up.  See pic.


The throttle body is completely dry.  See pic.


Won't be able to do the leak down until later in the week.

[dyermullet]

I had a turbo oil leak that only leaked into the exhaust side and not the compressor side.

I would find it hard to believe you have bad rings on a 14k mile original engine. Was the PCV full of oil?

[Joel Russo]

PCV was clean.

[Shimy87]

My money is on turbo seal.

[Joel Russo]

My money is on turbo seal.

How do I check that?

[Shimy87]

Like Steve said, oil in the up pipe. There should be zero. Take the pipe from the maf off the turbo and see if there is any back and forth movement of the turbo wheel. If it moves the turbo is probably pushing oil into motor.

[Steve Wood]

he checked the compressor side...so it's pull the downpipe off and see if there is any oil in the exhaust housing side.

After 27 years or so, the factory seals could easily be dried and failing...I was trying to eliminate the easy before popping springs off

[Joel Russo]

I'll pull the downpipe off this week and report back...


Thanks gents.

[Joel Russo]

I just pulled the downpipe and it's bone dry....

[dyermullet]

How much oil is it using?  any of the plugs showing any carbon from oil? 

If it was me I would decide if the oil consumption was too bad. If very little lost between oil changes I would ignore it and just enjoy the car. 

[bcn30141]

I suppose there is a possibility of leaking seal on the intake side of the turbo...

[626gn]

Had the same problem. Turned out to be the turbo seal. It is possible for the turbo to be bad without showing signs of of oil on hot or cold side.

[tb3]

X2 on a turbo exhaust side leak and didn't show any obvious signs looking at the exhaust whee, l or in the downpipe. 
it's probably going to show signs there eventually if you keep running it of course, 

may also check valve seals if nobody has mentioned those yet