Hello,

I have a '95 850 Turbo Wagon that has extremely high blowby. It has 96K miles on it and the compression is 150 in all cylinders. Because of the blowby it smokes-a lot when you engage the turbo. It idles very smooth and has tons of power on acceleration. Consequently, it is pushing oil out the oil filler spout, dipstick tube, etc. Any help in diagnosing this would be greatly appreciated.

Thanks!

Fasteddy,
The breather pipe on an 850T starts next to the oil filler cap and goes down the "front" of the motor. There is no PCV or flame trap.

Klaus
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98 V70Rawd(101Kmi), 95 854T(85K mi), 88 245(165K mi)

uhmmm the breather pipe IS the pcv (positive cranckcase ventilation)..but it has no flame trap, in fact NO later 850/v70's do and volvo (I am told by my dealer) now RECOMEND removeing the flame trap if fitted...


of course the turbo never had the flame trap itself butthe early NA did...

also checking my haynes the compression spec on a turbo is 11-13bar..which is 159psi or better so at a 150 your on the low side...

I realize that, I said there was no pcv VALVE on the 850 motor. Every motor has to have some type of crankcase vent.

I don't think that his having 150 psi of cylinder pressure versus the 159 psi spec in the book is a problem. He has a motor with a decent amount of wear on it (almost 100K), so deviation from the "as new" specification is to be expected, and it's not that big a deviation (<6%). Whats more important with regard to compression in a worn engine is the readings relative to one another. If he has a nice even 150 across all five cylinders then that indicates normal wear, but if he had 150 in 4 cylinders and 129 in one, then there's most likely a ring or valve problem in that cylinder, and in that case I would start paying attention to it.

whoa down boy! i was rplying to klaus who said 'There is no PCV or flame trap'

as new spec is 11-13 bar 159psi is 11 bar so 150 really is actually quite low as the range is 159 -188 (depending a little on altitude of course..)

but i think i agre with you i would look at crank case ventilation issue as it doesnt seem MASSIVELY low..but it could be the whole block is just worn, t here was a post a bit back abotu a block that had gone wavey at the top of the bores, leading to huge blow by but actually ok compression testing...

Just to check (since you said you have excessive blow by), are the plugs fouled with oil on all the cylinders? From what the kick inside was saying, it does sound like you are a bit low on compression. If your rings are bad, having a problem with your crankcase ventilation system could cause oil to get pushed up and cause the smoke. Not sure if having the turbo spool up at the same time as more smoke comes out is directly connected, or just connected with higher engine RPM.

And I think Hellboy didn't realize you were replying to Klaus and not to him. He must be touchy these days :)

Yes, I'm a little jumpy, to much caffeine. Sorry kick, thought you were directing that at me...

Everything I've read (or experienced) has said that, at that kind of mileage, unless the compression drop is at least 10% of the overall compression spec, then it could be considered normal wear and tear for a worn engine. Now what the definition of a "worn engine" is these days I don't know, 100K isn't excessive, but it's still pretty significant.

Red, please go back to the Supra forums and stop making trouble here amongst us lowly Volvo owners. You'd think you would have something better to do than harass us drivers of slow (relatively, some of the turbo bricks can move OK) sedans and wagons.

np...but thinking on lets assume 11-13 bar is the normal, so lets shoot for 12..or 174.0453 psi...so 10% would be 17.4 so he IS under 10% below really...

dunno but to relate this to my 940t with 145k on it and horendous oil usage (1ltr in 200 miles or so...) (still goes like a train though, but that may have something to do with the de-cat, custom exhaust and air inlet ;-)) that has a slightly unneven test but even the lowest cylinder is above the Haynes minimum...and i suspect the vehicle has been used and abused...

checked your crankcase breather pipework/ oil seperator?

I was told that I had excessive blow by and the guy cleaned gunk out of the pcv valve..(I think that is what it was). Recently I brought it to another guy who saw the same thing with the blow by. He also thought the pcv valve should be cleaned but then when I said it had been done a year or so ago he said that it could be the turbos would have more blow by anyway. I will ask him about it again when I pick up my car in the next day or so.
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'95 854T 120,000

Degunk the bosch idler valve. Remove the plastic housing over the throttle cable housing pully/linkage. You will also expose this idler valve and associated plumbing from crankcase. It gets fouled bad with oil residue and will hang up. This is an electro/mech solenoid and when cleaned should function with an slight audible "tick" sound as it cycles. Stay away from trich based solvents, use Isopropyl or mineral spirits and a swab. This component allows reingest of bypass gases into the throttle body for reburn and checks blurbo duct pressure from back flowing into engine. May not be sole cause of over pressured crankcase but certainly a contributing factor. Here's where frequent oil changes pay off. Reduced internal crud factor.

keep em running, nothing like um.

Gary

There is no PCV valve on an 850 motor, they have a piece called a flame trap. However, there is no flame trap on the turbo from what I understand (my car is N/A), only the oil seperator, check all that plumbing and the seperator, maybe it's clogged up. It sounds like you might have two seperate problems though. You might be getting oil smoke out the exhaust due to a bad internal seal within the turbo, where turbo oil is slipping past the seal within the turbo housing and getting vaporized and thrown out the exhaust, causing the smoke. This would require a turbo rebuild or a new turbo. The second problem might be related to the clogged crankcase breather plumbing as mentioned above, and causing the oil vapor your seeing around the motor.