850 oil leak mystery

I have a 95 850 GLT wagon with a mysterious oil leak that the repair
shop cannot fix. And this is a Volvo/Saab specialist, one of the more
reputable places in the region.

We've made four trips to the shop over the past three months. They've
had the car for a total of five days. Every time they think they have
the problem solved. The leak goes away for a few days, but then comes
back. First, they replaced the camshaft position sensor seal. A few
weeks later, they serviced the PCV system and cleaned the flame trap.
A few weeks after that they serviced the PCV system again and cleaned
the throttle body assembly. About a month later, they resealed the
rear cover plate and the rear of the cylinder head. Then about a month
after that, they replaced the PCV screen, the PCV nipple, the PCV
nipple O-ring, the balance shaft seal, and the chemical gasket
sealant. They also checked the camshaft and everything seems to be OK.
This last time, the leak went away for about two weeks, but now is
back again.

Does anyone have a clue what could be causing this?

 

by volvo-italiano dropped his wrench, scratched
his head and mumbled,

Have them clean the oil off again. Add tracer dye to the oil and check
with black light for the source of the oil trace.

Bob

 

I've seen quite a few 850s with the oil trap clogged from infrequent oil
changes and/or poor quality oil. Because of its design it's impossible
to clean properly, the only fix is replacement, which involves intake
manifold removal (long = expensive job).