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  #1  
Old 09-27-2002, 08:24 AM
r90skirk
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HELP - oil all over the place

Just wondering how many of you have experienced oil coming out the top of the oil dipstick tube. My wagon started leaking there 4-6 weeks ago along with a more severe leak towards back of motor - it drips down off from cross member behind oil pan (I suspect it's rear main seal).

It is a motor w/ nearly 300k on it so I'm sure I've got my fair share of blow-by. When I remove the oil fill cap while running, I get a light steady vapor puffing upwards and very tiny droplets of oil coming out onto top of valve cover. I've read a lot of posts about blow-by and nobody seems to answer the question of how much is too much?

Another question I have concerning blow-by is this: if I have blow-by, shouldn't I be burning oil? Prior to this excessive leakage starting I only consumed 1 1/4 qt. of oil in a 3000 mile interval. she does not smoke, the only time you see blue smoke is after cold start-up (probably valve guide seals). She still starts, runs and performs very well, plus I've not noticed any change in mileage.

I know I can just keep plodding along with her starting and running well, but she's making an oily mess - at a rate of a quart every 250 miles or so. I have to stay on top of it or else!

Would appreciate input here, thanks.

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  #2  
Old 09-27-2002, 11:09 AM
jcd jcd is offline
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Join Date: Jun 2001
Location: Northern New Jersey
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Get new o-rings

You can get new o-rings for the top of the dipstick,,,,,I think I got mine at a dealer, but I am sure that any correctly sized o-rings would be just fine. Just put a couple in and you'll get a tight fit.

I can't answer the question as to why you get so much blow-by that it would shoot oil out of the dipstick tube. Just hope tightening up the seal doesn't let pressure build up and shoot the dipstick thru the hood (kidding)

JCD
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  #3  
Old 09-27-2002, 11:27 AM
r90skirk
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Thanks JCD,
I've already robbed a better (used) o-ring off from my son's 240d and tried it a few weeks ago, granted it wasn't brand new, but it was more supple and a little fuller, and it didn't seem to help - not even slow the leakage down. I am going to place an order today and get a new one though, just to see if a new would make any difference at all.
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  #4  
Old 09-27-2002, 11:47 AM
Fimum Fit
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Have you checked your crankcase ventilation hoses for clogging --

It does sound like you've got a badly overpressurized crankcase.
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  #5  
Old 09-27-2002, 12:01 PM
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Skirk,

I think you mean the oil leaks are from the engine, not the motor because I've never seen a motor with a dip stick.

I would check to see that the breather pipes and hoses from the top of the valve cover to the intake manifold are not plugged. There may be enough oily residue in them to stop the crankcase ventiation system from pulling enough of the blow by from the engine.

P E H
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  #6  
Old 09-27-2002, 12:08 PM
r90skirk
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That was one of the first places I looked, and the breather hose is free and clear, under normal operation I do get some oily residue in air cleaner housing so I checked and rotated filter around to a more "clean side" orientation also.

Thanks to both of you for your ideas!
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  #7  
Old 09-27-2002, 08:40 PM
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Pull the dipstick up a little at idle and see if you have "puffing" blowby -- this will indicate a cylinder or valve guide gone south, blowing oil.

Another possibility is that there is more oil in the crankcase than you think and the crank is throwing it, but I doubt that.

Check the separator in the air cleaner housing, and the condition of the drain tube. If it is plugged, the only outlet for crankcase pressure is the dipstick tube, and it will pump oil out. Blowby will only "mist" the engine (the 220D has terrific blowby -- uses about a quart in 100 miles). Oil doesn't drip off the block, just coats everything.

I suspect something has blown -- either you have a valve guide gone seriously oversized, or a piston isn't sealing -- however, a bad piston will cause rough idle and performance/starting problems. A bad exhaust guide, especially if it has a bad valve guide seal, too, will puff pretty hard on the exhaust stroke, and can blow oil out of the dipstick. So can a hole in a piston, but again, rough idle and hard starts.

I would suggest attempting to replace valve guide seals. You can check valve to guide clearance at the same time -- if the valve has discrenable sideways movement when down off the seat, the guide is worn.

Peter
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  #8  
Old 09-28-2002, 08:02 PM
r90skirk
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Peter,
Okay, today I did a little more investigating. I pulled dipstick up out of tube about an inch; at idle, no puffing and no oil coming up. I worked throttle linkage to rev engine RPM's to I'm guessing 2500 or so and I could see puffing vapor coming out the end of the tube along with tiny droplets of oil trying to climb the inside of the tube.

I also performed the "plug the breather tube" test and recorded how many seconds it takes to shut down. If this is a semi-reliable test, this isn't good news; 2-3 seconds and she shuts down.

What can I check with the oil separator? I know the drain tube is connected to air cleaner housing, should I run a coat hanger down it to rule out any blockages?

Trust me, this isn't mist around my engine getting everything wet with oil. I have so much oil coming off the bottom of engine and engine compartment that now all of the hanging droplets get blown back (when I scoot down the road) and have completely covered the entire length of the undercarriage of car. Cheap form of undercoating, heh?

I'm not trying to question your input, but can you help me understand how a valve guide seal (worn) could do this?

And if it's piston rings (which I believe it probably is), why doesn't she burn more oil, smoke badly and start/perform poorly? That's the part that has me baffled.
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  #9  
Old 09-28-2002, 09:06 PM
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Kirk,

I thought you said you checked to see the crankcase ventilation was clear and not plugged. Look in the air cleaner where the fumes come out of the ventilation tube/hose and see if anything comes out there when you rev the engine.

P E H
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  #10  
Old 09-28-2002, 09:09 PM
r90skirk
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Yes PEH, the breather hose (from valve cover to air cleaner) is free and clear. "PSFred" asked me about the drain line from bottom of air cleaner housing to crankcase.
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  #11  
Old 09-28-2002, 09:48 PM
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Skirk,

I'm not familiar with the drain line from bottom of air cleaner housing to crankcase.

Have you tried removing the ventilation hose from the top of the valve cover and reved the engine to see if the blowby comes out there?

P E H
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  #12  
Old 09-28-2002, 10:50 PM
r90skirk
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Yes, and it does.
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  #13  
Old 09-29-2002, 12:49 AM
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Skirk,

OK, I'll give up on the crankcase breather system being plugged.
Guess you have too much blowby caused by worn out rings or maybe one broken ring.

I don't see how a leaking valve seal would cause your problem. It would not be an intake valve because there is only a slight vacuum on the intake valve stems which at worst would suck in some oil. It isn't likely it would be an exhaust valve because there is only manifold pressure on the valve stem which is very low compared the the combustion pressure in the cylinders.

With almost 300k miles on the engine, it could just be worn out. Did you do a compression test?

P E H

Last edited by P.E.Haiges; 09-29-2002 at 07:43 PM.
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  #14  
Old 09-29-2002, 09:27 AM
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A leakdown test will tell you if the piston rings or the valves are the problem. Simple test.
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  #15  
Old 09-29-2002, 08:45 PM
r90skirk
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I'm still confused!

I am fairly convinced that my oil leaking is due too excessive blow-by. But, I still question why this car isn't a mosquito fogger w/ smoke, because the way I've always understood engines is that if you've got bad rings, your going to be burning oil all of the time. Can anybody out there make some sense out of this situation?

Thanks.

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