occasional smoke from 86 740 turbo

Mainly it seems to be after I have driven a short distance (3-5 k),
switched off for a short time, then back on to drive home. One
mechanic thinks it might be a small oil leak, and doesn't warrant
attention right now. But it is embarassing to sit a stop light and
have a cloud go by! Not to mention environmentally irresponsible. I'd
say the smoke was whitish, but it comes from the rear of the car, and
could be bluish too. Not black.

Nothing after a long drive, nothing at normal start up, no apparent
drop in oil level, or increase in oil consumption.

 

I would be inclined to give the inlet tract a thorough cleanout including
turbo hoses and intercooler if fitted. The Positive Crankcase Ventilation
system could also do with a thorough clean (no filter in "Y" piece on turbo
cars). I would guess at a bit too much oil residue slopping around in the
turbo hosing/intercooler. The cleaning exercises should be done bi-annually.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

 

My guess:
Valve seals...I would just try to live with it...

 

i believe you should not. check out your intercooler
--

 

Hi,

You should check and clean all induction system hoses, then pcv stuff.
If none of this stuff works, then before I gutted the engine, I would
try an engine seal conditioning additive or oil, ie. Seafoam, or
Valvoline Max Life synthetic (respectively). These things have
additives that recondition, and sorta swell gaskets and seals. If this
clears it up, great. I would use its efficacy as more of a diagnostic
than a fix, but it may work for a while if seal damage is the culprit.

Best o' luck,
-Z-

 

I agree with Peter - clouds of blue smoke at idle in one of these beasts (I
have an '85 765T) is a good indicator of crankcase ventilation trouble. Why
it shows up mainly at idle isn't clear, but that's been my experience. In
any event, back pressure causes the oil to back up into the turbo and spill
into the exhaust - yuck!

Pull off all the pieces of the ventilation system: the hose that runs across
the top of the engine, the plastic "Y" and the oil/air separator box under
the intake manifold (it's held to the crankcase by two screws). Clean them
up and check for restrictions, especially the separator box. Blowing through
each should feel like you are blowing through a 3/8 inch hose; you should be
able to exhale in 3 seconds or so. The separator box is more practical to
replace than to clean if it's plugged. In my case even the large hoses were
nearly plugged.

Don't forget to wipe the black ring off your lips after each restriction
test!

Mike

 

My wifes car did this too ,much to our embarrassment at times .It sure was
smoky but not all the time turned out the oxygen sensor was gone new sensor
and all is fine as well as better fuel economy at $1.40.9 a litre we sure
are need to keep it well tuned .