excessive crankcase pressure

also see this email on excess crankcase pressure.

Most recent response:

To the first post: Just below the intake manifold is a box which separates oil from the vacuum stream
in the PCV system. This box is called: "Oil Separator" by Volvo (strange as Volvo often uses strange
names for everything). If this box is clogged then exess pressure can build up in your crankcase. In
addition, oil will enter the PCV system, Intake tubing, Intake manifold, and cylinders. An easy way
to check if this box is clogged is to pull off the intake and PCV tubing around your throttle body
and look for oil. Your throttle position switch may also have oil in it. If there is oil there then
you know you have to clean or replace this box and its tubing (Unfortunatly this requires removal of
your intake manifold). If there is no oil in the tubes, that does not mean the box is ok (the box may
be so clogged that NO OIL OR VACUUM is passing). I had the same problem with my 1993 850 GLT
Non-turbo, and replacing this box solved it. It also gave me a chance to clean, port, and polish my
intake manifold and head.

I hope this helps (even if it's just a little),


Serious Issues with Engine/Oil Pressure [850][1995 T-5R] ... posted by Jonathan Dunlap  on Monday, 19 March 2001, at 7:38 p.m.

                       This one is for the books...

                       I have three problems with my 1995 850 T-5R, all of which may be related / maybe not, and if I wasn't
                       a masochistic engineer I would have sold this car by now... I bought the car at 70,000 miles, everything
                       was clean as a whistle (I'm not saying it wasn't totally spit polished for me on the lot)...

                       Since I've bought the car I've noticed little bits of oil, drops on the top of the engine, I always assumed
                       that it was a leaking filler cap, so I replaced it. (I still have the random drops).

                       Last time I changed the oil (75,000) I noticed what could be seepage from the main seal. (That
                       combined with suspicious air conditioner has led me to buy a warranty from warrantybynet...)

                       Today I was on a rather long drive (150 miles), and on a long strech of highway I had the chance to let
                       her run wide open, after reading many other posts recently (you people are a bad influence). First, she
                       maxed out at 134 MPH on a very flat stretch, not bouncing off of the rev limiter, but stopped by drag
                       (There goes the dreams of 150+). Second I experienced a re-occuring problem. On long trips I've got
                       this problem where after the engine/tranny heat up pretty well, I seem to get this horrible shift between
                       third and fourth (51-53MPH). It's very clunky and seems to have to guess between the gears. It actually
                       makes the car clunk, and buck and once made the check engine light come on. The other symptom is at
                       rest, the car very harshly clunks into gear between reverse and drive. The only codes left were misfires
                       in each of the cylinders.

                       Being paranoid of the tranny, I flushed the system four months ago, since then I've been unsure of
                       whether I have the correct amount of fluid in there so I check obsessively. It seems to be right on...

                       So today when it was acting up, I checked the tranny fluid at a rest stop. It seemed fine as always, sitting
                       at the top of the hot line. BUT what I did notice is that I had a few small drips of oil coming out and
                       running down my oil my dipstick tube. Nothing at all from the filler cap with the new gasket. And at the
                       expense of a pair of dockers, there's more evidence of seepage at the rear seal.

                       So here it is:

                       Are these connected? It would seem as if my oil pressure is too high. Causing oil to come out both
                       orafaces. What could cause that besides the relief valve in the oil pump (no flame trap in the turbo). Are
                       these problems related, or seperate, or should I just take it to a dealership and play totally stupid? I'm
                       hoping that some of the brilliance of John O, or Dave, or anybody who knows these cars better than me
                       can help. I have posted a few time now, and all of your help has been invaluable in the past.

                       Thank you in advance,
                       and sorry for the length,

... posted by J. Hawthorne on Monday, 19 March 2001, at 10:27 p.m. ...in response to "Serious Issues with Engine/Oil Pressure" posted by Jonathan Dunlap.

                       High oil pressure would not cause oil to come out of your engine dipstick tube, but high crankcase
                       pressure sure would cause that and also would force oil past the rear main seal. Have the dealer check
                       engine for excessive blowby, plugged pvc system etc. When you checked the engine was the dipstick
                       fully in the tube or had it blown out? Also have you checked the o'ring in the dipstick handle for
                       I don't know about the 850's but in the S70's I believe the top speed is electronically limited by cutting
                       off the fuel injection and when we did our "Italian tuneup" we still had plenty of revs left on the clock at

... posted by Prospero  on Tuesday, 20 March 2001, at 7:42 a.m. ...in response to "Sounds like excessive crankcase pressure." posted by J. Hawthorne.

                       Sounds like you could be getting blow back as well as it could be a clogged PVC system. I have also,
                       albiet rare, seen a bad oil filter cause similar problems. What is the condition of the oil? Does it look or
                       smell funny? Any moisture in the oil or dipstick tube? What brand oil filter do you have on? If it is not an
                       OEM volvo filter, loose it and put a Volvo filter on. When was the last oil change and who did it?

                       Also, on my 94 854 Turbo I ran out of steam at ~130 mph as well. A week later I found a leaky turbo
                       downpipe hose (1/2" hole from the inside out!). Replaced it and the car goes much, much better now.
                       You may have a few loose hose clamps or leaky turbo duct work slowing you down. Good luck.


... posted by Jonathan Dunlap  on Tuesday, 20 March 2001, at 10:25 a.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Prospero.

                       I agree with the high crankcase pressure comments, mental slip when I said oil pressure...

                       Bought the car at 69,674 independent dealership stamp said oil had been changed at 70,000 mile
                       service (car had OEM Volvo filter and I don't know the oil type). At 74,500 I changed the oil to Mobil
                       1 10W30 with a volvo filter. I'll check for moisture in the dipstick, but I'm not sure exactly what I'm
                       looking for. Condensation in the tube? Being an engineer in a lab I've had the luxury of running chemical
                       analysis on my oil. I ran FTIR (Furrier transformation infrared spectroscopy) Which won't tell me
                       specifics on degredation, but it will show contamination, and shifts from the baseline (a drop of mobil 1
                       from the bottle). I ran the baseline and my oil this morning the both check out identically.

                       So now I'm puzzled. I know there's no PCV valve (flame trap) to clean on this car. What should I check


... posted by Prospero  on Tuesday, 20 March 2001, at 12:32 p.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Jonathan Dunlap.

                       The problem you seem to be having can be so many things...But I guess to start, when looking for
                       excess condensation in the oil you will see what appears to be fog in the oil in mild cases. In extreme
                       cases the oil will look like coffee with cream and sugar, or even chocolate milk. The oil will also have the
                       tendency to smell musty at times. This will all be visible when checking the oil on the tip of the dipstick.
                       Condensation, appearing as milky stuff on the top of the dipstick and tube is normal to an extent. If you
                       do not drive for 25 miles or so a day and allow the motor to run at operating temperature for ~25 min or
                       so, you will probably see this. The condensate will also appear on the bottom side of the oil filler cap. It
                       too will look like milk. If I had to put a specification on a quantity of condensation, I would say no more
                       than a few grams between the dipstick tube and oil cap is normal. Since you and I are running the same
                       oil, with the exception of me using 0-W30 vs. 10-W30, just as a benchmark I go about 2000 miles
                       before my oil begins to get dark. At 1000 miles the oil looks like iced tea, 2000 miles weak coffee.
                       How does yours look? BTW, I normally drive <5 miles a day, so condensation does show on my
                       dipstick within a week or so. I hope I did not add to the confusion. Hope all works out for you.


... posted by Jonathan Dunlap  on Tuesday, 20 March 2001, at 5:14 p.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Prospero.

                       Prospero, you're right, I have a tad amount of condensation. -Just like you said at the top of the
                       dipstick, and under the oil filler cap. The oil itself does look pretty good. 2400 miles on it and it's pretty
                       regular in color for that milage (not opaque, or burnt smelling, but definitely not out of the bottle).

                       Not to write another book, I cleaned everything very well (dipstick, rear main seal area, top of engine
                       area...), and then ran the hell out of the car. First some high speed driving 130 sustained for 4-5 minutes
                       after 30 minutes of highway driving. Then check for leaking oil blowing out:

                      Rear main seal=none
                       Filler cap = none
                       Dipstick = the smallest trace...

                       Clean everything once again. Time for a Italian tune-up. High RPM's 4-6K for 4-5 minutes straight.
                       Stop the car. Check again for oil

                       Rear Main Seal = Definite Seepage
                       Filler cap = none (possibly a small trace)
                       Dipstick = Major amounts of blow out. Dripplets everywhere spattering all over that area of the engine.

                       So I definitely have a crankcase pressure issue. Now to determine root cause...

                       Anybody have any suggestions?


... posted by Dave E. on Tuesday, 20 March 2001, at 6:02 p.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Jonathan Dunlap.

                       > So I definitely have a crankcase presssure issue. Now to determine
                       > root cause...
                       > Anybody have any suggestions?

                       > Thanks,
                       > ~Jonathan

                       Is it possible the crankcase ventilation hose is clogged or pinched? Not sure where it is though.

... posted by Wayne bosman  on Tuesday, 20 March 2001, at 7:04 p.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Dave E..

                       Since volvo turbos dont have a flame trap per se, the engine blowby and crankcase pressure are vented
                       through a multi purpose valve that is in the iintake bellows. there is a vacuum line to the valve that gets
                       kinked and porous from the gasses going through it and it often implodes. the valve itself gets plugged
                       up from carbon deposits. try clearing the nipple on the valve. Rout it out with a paper clip or something.
                       the other end of the vacuum line goes to the intake manifold near the thermostat housing. this one also
                       decomposes. volvo has changed part numbers for this, so they probably kinow they have a problem

... posted by Jonathan Dunlap  on Tuesday, 20 March 2001, at 8:11 p.m. ...in response to "Re: Sounds like excessive crankcase pressure." posted by Wayne bosman.

                       Thanks so much,
                       I'll go over that whole system tomorrow. I've been meaning to clean the throttle body, I have the gasket,
                       so I'll start at one end and roto-rooter the entire system.

                       I'll post my results...

                       Thanks everybody,

                       If anybody has any more suggestions please let me know...

Still Stumped... [850][1995 T-5R]... posted by Jonathan Dunlap  on Thursday, 29 March 2001, at 6:36 p.m.

                  1995 T-5R (A fun little turbo)....

                  I posted about 2 weeks ago about excess crankcase pressure which seems to be
                  causing a rear main seal leak and small amounts of oil to come spewing out my
                  dipstick. Even though its a turbo, some people on the board suggested I clean
                  out my throttle body and everything associated with it. I've done this today. The
                  throttle body was dirty, but all of the associated breather lines were very clean,
                  and their elbows were all very pliable and intact. I put the whole thing back
                  together. Degreased the entire engine, and then opened her up.

                  Same problem, I still have the problem. After 30 minutes of good hard driving,
                  there's oil falling down the dipstick tube and spattered on the fuel rail. My rear
                  main seal also shows some seeping.

                  What can cause this. Somebody suggested water/condensation in my oil, but I'm
                  not quite understanding that theory. Being that my car has 79,000 miles I find it
                  hard to believe that my rings are too worn and causing blow-by, but is this my
                  only option left?

                  Any help anybody could give would be greatly appreciated,

... posted by John O on Thursday, 29 March 2001, at 6:59 p.m. ...in response to "Still Stumped..." posted by Jonathan Dunlap.

                  Have you inspected all the vacuum hoses and other PCV related hoses? Take a
                  good look at the vacuum hose from where it connects to the intake manifold
                  behind the PS pump at one end and where it exits near the turbo inlet (intake air
                  hose by a lower sensor) at the other end. If that hose leaks, you'll build too
                  much boost and that could contribute to your problems.

... posted by Arno Griffioen  on Thursday, 29 March 2001, at 11:43 p.m. ...in response to "Still Stumped..." posted by Jonathan Dunlap.

                  Wild-ass-guess, but here goes..

                  There should be some one-way valves in the crankcase ventilation tubing, so it
                  will suck the vapors directly into the intake manifold when not under boost, but
                  the valve closes when under boost and the vapors are redirected to the turbo
                  intake side (still a little pressure-drop).

                  If the valve from the intake manifold is broken (blown or something), then the
                  intake boost pressure will probably pressurize the crankcase..

                  Hope this helps..

                  Bye, arno.

                  S40T4M with TME ECU upgrade and exhaust, using 215/40R17 Toyo Proxes
                  T1-S tires on O.Z. F1-Cup wheels

... posted by jeff yeoh  on Friday, 30 March 2001, at 5:50 a.m. ...in response to "Still Stumped..." posted by Jonathan Dunlap.

                  I had the exact same problem on my 855T5A (72,000km then), and mine took a
                  while to figure out.
                  Some time after an oil n filter change, i began noticing little pools of oil
                  appeared under the car overnite, later i narrowed the occurence down to it
                  "leaking" only after a hard drive. Much later, after a hard(er) drive on the
                  highway i noticed engine oil all over the top of the engine. but on all
                  occassions i checked the oil level to make sure it was sufficient, and it was.
                  after a while i began to suspect overfill, with the oil spurting out of the dipstick
                  funnel. if i recall right, the dipstick was showing some half cm above the max
                  mark. next service, i replaced the engine oil and ENSURED the mechanic
                  filled only to the halfway mark. (them mechanics seem to always think the oil
                  level will go down a lot once the engine's started and they "compensate" by
                  overfilling) no more problem ever since.
                  hopefully this is the cause of your oil leak cos the solution would be so simple.

                  95 855T5A, SAM chip, IPD swaybars, full S/sprint exos, Bilsteins


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