Doc67 had a pressurized manifold and traced his problem to the PTC nipple valve which was cloggged. I brought this item to the problem list because all of the turbos since 1990 have a PTC and they tend to get clogged during cold weather.

"The PTC Nipple is mounted in the cold air intake pipe that runs from the air filter box to the turbo. It is in the elbow of the pipe, nearest the turbo. It has two vacumm hoses connected that run back to the oil trap. There is also an electrical connector. It looks like your typical piece of electical mumbo jumbo stuff. It is not very large, about the size of a spark plug.

I am not sure what its actual function is, but it passes the crank case gases back into the engine to be burned. I have been told that it may be a device to heat the gases when the engine is cold. Regardless, mine was blocked and I had way too much pressure in the crank case, causing oil to blow from the filler cap."

I hope we all learn from each other,

Klaus

--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

From Doc67:

"It is not as bad as it looks.
Take the top of the air cleaner off and disconnect from the hose.
Disconnect the two hoses at the top of the cold air pipe.
Disconnect the two hoses and electrical connector from the PTC.
Disconnect the hose clamp from the turbo and pull the whole cold air pipe
out.

Don't even think about trying to get the PTC out of the cold air pipe
without removing the cold air pipe. It is still difficult to get out even
when the cold air pipe is out of the car.

Also, my cold air pipe had disintegrated at the turbo connection, causing
the intake to suck lots of air. You may want to check it out at the same
time. The dealer told me today that it is a common failure."

Of course, all dealers say that. If it is so common, why doesn't Volvo do something about it? Buggers!

Klaus
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

Thanks Klaus. Was the valve easy to clean, or did you replace it?

Oh, by the way:

I did end up replacing the valvle.
The cold air intake hose was disintegrated so I ordered a new one.
The new hose came with a PTC installed for $130 CDN.

Doc67 said it was easy to clean. You have to take off the breather hose/pipe to get access which means warmer weather for me. Good time to clean the electric switch leads also.

Klaus
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

Thanks Klaus. Adding that to the spring/summer "todo" list...

Klaus,

you're right, that PTC nipple valve is actually a warmer valve and it's supposed to be patent and works with vaccuum from the intake.

When the valve fails, cold fumes/gases condense and eventually clog up the system.

Good pickup buddy.
--
'88 240, '92 745, '98 v70 John, Tampa Bay