posted by
someone claiming to be Dan
on
Mon Mar 8 16:19 CST 2004 [ RELATED]
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Hello Brickheads:
The inevitable has occured. The rear main seal in my 1996 Volvo 850 -non turbo (81,000 miles)is leaking oil. There is no way this should even begin to happen until way after 100,000 miles. The rate of leakage is 1 quart of oil at highway speeds 70 mph plus per 150 miles or one half quart per 2 weeks driving around city streets. I am aware that this is a common problem in the 850 due to an inferior original rear main seal which Volvo installed in this vehicle and others. After reviewing the archives in this forum, I noted references to "excessive crankcase pressure" as and additional cause of seal failure. I noticed that the engine valve cover is seeping oil also. I am saving up my pennies for the $500-$800 rear main seal an valve cover seal job and am not a happy camper. I suspect this problem is caused by multiple factors and want to repair them now.
Does anyone know the cause of this reported "excessive crankcase pressure"? I do not want to go through this expense again. Please note, I change the oil myself (and do not overfill) every three thousand miles or three months. I examine and clean the flame trap (pcv system) at every oil change. It has never been plugged.
Your in input is appreciated.
Dan
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What is your oil change history?
Flame traps typically plug-up due to poor oil change habits.
The original rear main seals are NOT problematic and generally leak due to outside forces, most of which are related to oil change history.
I have numerous customers who religiously change oil every 3 months-3,000 miles and still have original flame traps and no leaks with more than 100,000 miles on them. Just yesterday a good customer {'98 S70, 132,000 miles} came in for his 3,000 mile Mobile 1 oil change. He still has the original flame trap!
I also have a few customers who don't change their oil often enough and wind up not only with plugged flame traps but plugged oil separators too!
Oil changes are required because oil gets dirty. The chemical "sponges" get saturated and the only fix is to get it out of there! And NO!! synthetic oil does NOT mean it can stay in longer, it gets just as dirty, just as fast. Synthetic gives wider operating conditions but still needs to be changed every 3 months- 3,000 miles.
That plastic box under the intake manifold,{the one the flame trap hose goes to}, is the oil/vapor separator, it will become restricted and cause a high pressure in the crankcase resulting in leaks. Rear main leaks, new oil cap seal leaks, leakage where flame trap/pcv hose attaches to inlet pipe etc., and dipsticks blowing out and leaking.
While not all oil leaks are a result of lack of oil changes, my 22+ years experience in professional Volvo repair indicates most ARE due to this.
Knowing this obviously doesn't remedy the situation, so... the only repair for a leaky rear main is to replace it. This requires special tools so if you don't want to pay 5-800 dollars, maybe you can pay a Volvo tech "on the side" and get it done cheaper. If you do it yourself, use the tools. There is nothing like doing it twice, and you will especially if the seal installation tool is not used.
Good luck
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posted by
someone claiming to be Dan
on
Sat Mar 13 08:08 CST 2004 [ RELATED]
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I change my oil every three months or 3000 miles.(Castrol 10w30-regular oil and a Volvo oem filter). I remove and clean the flame trap at each oil change. I install a new one once a year. The Volvo 850 Haynes Manual (Section 6-2) says to use compressed air to clean out any lines into and out of the flame trap container when cleaning or changing the flame trap. I do not have an air compressor and have never "blown out the lines". I like your idea regarding a plugged oil/vapor separator as a possible cause. I have a dealer trained volvo technician who does work for me on the side waiting to do this job. He does the things one should not try at home-rear main seal- evaporator etc. I wanted to make sure I understood the problem before giving him the job**. I wanted to cure the primary problem (high crankase pressure) and then fix the secondary problem (leaking rear main seal). I do not want to go through this procedure again for a very long time.
Dan
**As a former 240 owner, I replaced several "cooked" air mass meters because the technician (not my current guy) repaired the symptom (air mass meter-for $300-$400 a pop) rather than solving the problem --a defective air box thermostat valve --a $20 part. Therefore, I try to understand the problem before I pay a technician.
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Sounds like you have your bases covered.
Based on your oil change history, you probably don't have excess crankcase pressure due to your PCV system.
Sometimes those rear main seals fail, also the 4 smaller bolts that install vertically at the rear {flywheel end} of the engine can leak around the threads. It is required that the threads have sealer applied and on occasion I have seen leakage which resembles a rear main leak.
A side note on the leaky evaporators, why go to all the expense? I have found that in most cases the evaporator leaks so slowly that a once a year A/C service suits most of those that leak. Rarely does an evaporator leak so badly it won't hold a reasonable charge throughout the hot weather.
Anyway, good luck with fixing the leak.
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Hi there - UK newbie to this forum, but makes excellent reading. Unable to offer any help on this but replying on the same subject!
Interesting reading the replies on this subject...I hope Dan manages to resolve the problem without the expense of a new rear main. Speaking of crankcase pressure, I have an 850 turbo which does not have a flame trap so where could excessive crankcase pressure come from? I assume rings are the only other possibility. My concern is that my main seal has gone as well (2 pints a week), but I do have oil in the wells under the plastic spark plug cover. Would this be because of a leaking sealing ring on the filler cap (the rubber does feel very stiff, not at all flexible). If it is, could this leak be because of excess crankcase pressure or just a useless sealing ring? My dip stick stays in it's tube. Sorry but one other question I have - a drip of oil that runs down the rear of the timing belt (serpentine?) cover when the engine is running, it appears to come through the join in the plastic cover about 6 inches up from the bottom fairly constantly - re-appears after wiping it away after 10 to 15 seconds. I've heard that this can happen if the rear main seal has gone, I confess I can't quite work that one out. Could somebody confirm where the seal is for me?! Is it possible to have a leak from the crankshaft seal on the timing belt side of the engine? Going to replace the oil feed seals to the turbo...desperate attempt at avoiding rear main seal nonsense.
Greatful for the information in this excellent forum and thanks for any advice on this!
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posted by
someone claiming to be Dan
on
Tue Mar 9 14:15 CST 2004 [ RELATED]
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Thanks for your advice everyone.
I will follow up on your recommendation to check the vaccum line between the flame trap housing and the vacuum tree and the hose which provides vacuum to the oil trap. I just noted that the Volvo 850 Haynes Manual (Section 6-2) recommends using compressed air to blow out the lines leading from the flame trap cannister when cleaning or changing the flame trap (I have not done this in the past when cleaning or changing the flame trap.)
I doubt it is a broken piston ring as the car runs smoothly, I drive like a little old lady and I am a maintenance nut who rarely fails to read the last line describing maintenance procedures in a service manual(as I may have done in the above described situation in the previous paragraph).
Dan
PS A note to the responder who wanted to know where the rear main engine seal is located: It is on the right side as your are facing the engine looking under the hood. Rear main seal is a bit of a misnomer as the engine is transverse mounted. It should be called the right main seal. It connects into the transmission which needs to be removed and reinstalled. The $27.50 seal can be installed in a few short minutes which takes 8-10 hours of labor to remove and reinstall the transmission so you can get at the seal--at $50-80 per hour is not a job to do at home. Once the seal goes it must eventually be replaced. It will only get worse. When it leaks at high speeds on the highway it spews oil eveywhere under the vehicle making you think it is leaking elsewhere. The mess needs to be cleaned up several times to allow you or your technician to carefully observe the leak location. When all is said and done, it if often the rear (right) main engine seal. Rumor is that Volvo is now producing a new and improved seal--which they should have done in the first place.
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Thanks for the depressing info Dan...if the engine can be cleaned properly, where would one expect to see a leak from the rms? could it appear from the seam of the timing belt case as I was told?? - seems odd to me though.
Thanks again...
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"Rear" of rear main seal refers to the rear of the engine.
The rear of the engine is not the part of the engine nearest the back of the car. The rear of the engine, regardless of an in-line placement, or a transverse placement, is the end of the engine opposite number one cylinder. Which is why is is still called a rear main seal rather than a right main seal.
The timing belt is at the front of the engine, nearest the number one cylinder.
So, leakage from the timing belt cover has nothing to do with your rear main seal.
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Well those were my thoughts indeed - exactly.
Many thanks for the confirmation Ken
Deadfunky
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Everybody has got this knee-jerk solution, "remove the flame trap."
But in many, many instances, and in this instance in particular, the owner examines and clean his flame trap at every oil change and attests that it has never been plugged.
And there are plenty of people out there who have had a blown rear main seal and had their flame traps tossed long ago.
If you have a flat tire, the flame trap is not to blame.
Likewise, if you have high crankcase pressures, the flame trap may be to blame (if it is clogged), but may not be to blame. There are many other issues which could cause this condition.
I also have a 96 N/A 850 which had the same problem--high crankcase pressures. The first sign was the oil filler cap leak. The flame trap was wide open at that point (I had just replaced it). To "solve" the oil filler cap leak, I replace the oil filter cap seal. The next day, I went to check the oil and I notice that the dipstick had popped out. After a little investigation, I finally realized that I had an excessive crankcase pressures issue. It turns out that one of the fittings/hoses providing vaccum to the oil trap had broken so that vaccum was not being applied to the oil trap and crankcase pressures rose.
A more dire explanation might be a broken piston ring. A broken ring would easily create high crankcase pressures. You would probably see other symptoms, if this were the case, but it is a possibility.
So, to all those flame trap killers, solve the real problem. Don't just blame the flame trap.
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posted by
someone claiming to be 93-940 & 99-V70
on
Tue Mar 9 06:26 CST 2004 [ RELATED]
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You have some good points. In fact, the leak could have nothing to do with high crankcase pressure, and could just be a failed seal. However, a high percentage of seal leakage, especially with fairly low mileage, comes from a clogged flame trap. And often enough, just cleaning the trap can cause the leak to stop. Always worth checking the flame trap first. Volvo also always looks there first (at least the dealer I go to).
God I hope it's not a sufficiently broke piston ring.
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posted by
someone claiming to be yona
on
Tue Mar 9 04:07 CST 2004 [ RELATED]
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The leak on my car has reduced since I took out the flame trap some weeks ago. No more spots on the ground. I also check the dipstick every other day and it has stabilized sort of. But i still plan to get it changed in summer.
yt855
1994 855 5 spd non-turbo.
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posted by
someone claiming to be 93-940 & 99-V70
on
Tue Mar 9 02:24 CST 2004 [ RELATED]
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Most common cause is a clogged flame trap.
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I'm not sure if your car has one, but check to see if the vacuum line going from the flame trap housing to the "vacuum tree" is not clogged and is open. Other than that, I too have read many posts on the forum and others in hopes of preventing rear main seal failure. I can't really suggest any other causes except that oil leakage is inevitable.
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posted by
someone claiming to be joe
on
Tue Mar 9 02:10 CST 2004 [ RELATED]
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Check/replace flame trap ( under $1 item ).
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yes your car has low milage but age is working against all us volvo 850
owners, your car was built in 95 it pushing 9 years old,
I agree the seal should last the life of the car .
most volvo techs take the flame trap out of the car, My 97 was removed
by the dealer.
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