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#18441 of 19336 Source of dirt on clutch plate??
Dec 24, 2009 (7:49 am)
Have a 2001 Outback, Manual with about 120K miles - mostly local short trips for the past couple of years. Got it used and replaced clutch (bad slippage problem) about 3 years ago. Clutch just went again (bad slippage again - after about 30K miles on it). Took it back to same mechanic who was surprised and concerned about early failure (he had put heavy duty Subaru parts in first time). When he took it apart, the clutch plate had lots of dirt on it and was gone, the release bearing was in bad shape and the Clutch release lever seal had disintegrated. So he feels that some oil or dirt got in and caused the failure, but the problem is that he can't see any source of the problem - so he's afraid that it might continue to happen again. Any ideas that I can give him about the possible source of the contamination? Thx.
#18442 of 19336 Re: Source of dirt on clutch plate?? [ffen]
Dec 25, 2009 (8:33 am)
"... the clutch plate had lots of dirt on it and was gone, the release bearing was in bad shape and the Clutch release lever seal had disintegrated. So he feels that some oil or dirt got in... Any ideas that I can give him about the possible source of the contamination?"
This mechanic is replacing your clutch for the second time, and should have his own good ideas about why.
When he replaced the first clutch, did he note its condition and why it slipped? Did he replace the release bearing and seal?
Dirt per se does not get into the clutch housing. What he is calling dirt is lining dust. Oil can get into the clutch housing from either the engine's rear main seal or the transmission's input seat. If those were the cause of the first clutch's slippage and were not replaced, that could account for the second clutch's short life.
#18443 of 19336 Re: Source of dirt on clutch plate?? [aatherton]
Dec 25, 2009 (4:04 pm)
Pay attention. from a small fleet service maintainer.
Subaru back of engine is not the norm. Normally from what we have seen, the rear main oil seal is not the cause of oil leakage. What the source of oil leakage is the oil separator plate in the PCV system. OEM units are plastic. Replacement part from Subaru is aluminin. On the other side is also a $5 o ring from Subaru which is the oil galley area as well. Replace the o ring, the oil separator plate and the rear main seal to eliminate any leakage from the back end before doing the clutch. They will cause the clutch to fail if ignored.
Now, when I replaced the oil separator plate, The OEM gasket was silicone only. I replaced with a hand made very thin paper gasket coated on both sides with a very thin coat of the black silicone. The o ring I recall as only being done with thin film of silicone used. Be sure to clean off all old silicone and grease before the final reassembly. Make sure those access screws are also well torqued in place.
WE had to use a small hand held impact screwdriver to remove these screws. Purchased it from Home Depot. They are not screws you want coming back out again either. So make very sure they are lock tite or staked or whatever it takes to keep them installed.
If you are not sure if your car has this, take the VIN to the parts department of a Subaru dealer and have them pull up the rear of the engine looking for an oil separator plate. If you have it, you have a problem if it is the old plastic one. I would still service it while down for a clutch to prevent future problems. Ditto on the rear main and o ring evn if not leaking. They will fail before the clutch wears out next time from normal use.
Unit procedure completed on, 97 Subaru Brighton wagon with 2.2L engine. 5 speed standard. Service point, 240K miles. reason for service, clutch, wheel bearings and front end work. Service date, March '09. Operation status, open road, MO area. Next major service due at 345K. Good luck on your car, hopefully this info will help you out.
Dec 26, 2009 (6:32 pm)
Very correct pictures. The way it works is simple. You may know already that as an engine wears out the engine blowby increases. Along with that blowby is more oil vapor. Which in time will flood the intake system with liquid oil with higher engine loads.
The way the separator works is it forces the vapor to hit cooler inside flange surfaces and condense back to a liquid flowing back to the crankcase before it gets into the breather system as a vapor. With a flywheel flying right next to it outside, and the cover being a heat sink, a few degrees get dropped quickly. Neat arrangement, but a pain for over all maintainance because its failure forces a clutch job at 240K before it was even needed for a professional driver. One reason Subaru is possibly getting dropped from the fleet here. Guess we getting lazy here. I remember clutch jobs around a 100K!
Another note. Not sold on the fujibonds performance. It clearly failed once already!That is why we installed with a paper gasket coated with black silicone. Time will tell how well it holds up. One thing for sure, fleet service gives back hard tested answers! The silicone helps secure screws and come time for replacement, hopefully never, it acts like a teflon to remove that old paper gasket. During service it works like elmers glue holding the paper gasket in place very nicely. Thin coat can not be stressed loud enough. Thinner, the better.
Oh, well, so the world turns. We all live and learn. Subaru still has a hard to beat system for snow, but they are getting their vehicles too large.
#18446 of 19336 Re: Source of dirt on clutch plate?? [aatherton]
Dec 27, 2009 (11:29 pm)
Thanks for responses aatherton & girlcarbuilder.
> This mechanic is replacing your clutch for the second time, and should have his
> own good ideas about why.
Actually, he's puzzled about why it happened so soon and was searching for possibilities (which is why I posted here).
> When he replaced the first clutch, did he note its condition and why it slipped?
> Did he replace the release bearing and seal? "
Not sure. I know he didn't replace seal, I think but am not sure he replaced bearing.
NEW INFO - My guy had some friends who were transmission specialists look at the parts, and they said they couldn't see any oil, just clutch plate debris. Subaru dealer service manager said that 30K / 3yr clutch replacement was normal (seems kind of short to me ...) . My guy will be showing the parts to the service mngr tomorrow. I will also forward info on oil leak prone areas to my guy to take a look at. Thanks all for your responses.
#18447 of 19336 Re: Source of dirt on clutch plate?? [girlcarbuilder]
Dec 28, 2009 (4:50 pm)
"... the source of oil leakage is the oil separator plate in the PCV system... Replace the o ring, the oil separator plate and the rear main seal to eliminate any leakage from the back end before doing the clutch. They will cause the clutch to fail if ignored..."
What effect does oil leakage from the separator plate have upon an automatic transmission?
#18448 of 19336 Re: Source of dirt on clutch plate?? [ffen]
Dec 28, 2009 (5:00 pm)
"... couldn't see any oil, just clutch plate debris. Subaru dealer service manager said that 30K / 3yr clutch replacement was normal..."
By debris, do you mean particles of clutch destruction, or dust worn from the friction plate? Big difference.
Service managers say all kinds of weird things to suit the situation. Clutches should last 100K to 150K in normal use, depending on the shifting habits of the normal driver. Many drivers are hard on the clutch without even realizing it.
The life can be greatly shortened by true abuse, an inferior clutch plate, or oil contamination.
#18449 of 19336 Re: Source of dirt on clutch plate?? [ffen]
Dec 29, 2009 (9:18 am)
Okay, I am going to answer several people at the same time. First concern: If it has been definitely confirmed that there is no oil leakage, meaning you do not have oil on the back of the engine and it is clean except for dust only. Then and only then do you not have an oil leak. If you have black crud, dust and oil combined on the back of the engine, it will get on the clutch plate in small amounts and be burned off by it, the pressure plate and the disc. You may only see evidence of bluing on the clutch plates. I did not see leakage actually on ours until I cleaned the rear of the engine and it sat for several days. It was a little thin drip from both sides of the engine that would fall onto the edge of the flywheel. More noticeable from the o ring than the plate. I suggest you ask how often the owner has to add oil. If he has to put much more than a quart every 2-5K miles. I would strongly suspect the seals. A 240K unit here after service needs a quart about every 2K. When I say clean, I mean clean enough to eat off of. If your mileage is close to 100K or more and that oil separator has never been serviced, do it, the rear main and the o ring. It will be a problem in the future if it is not now.
Second question: automatic transmission application. The concern comes to play when you start seeing a lot of oil loss. That could very well mean either the rear main has failed or the screws on the plate worked lose, which I doubt because they are a pain to remove. The torque convertor is a sealed unit that it can not harm. It will just fling the oil off to the outer perimeter. If you ever pull the tranny, service it then.
There is a 94 Legacy here with that problem. 4 speed auto. Been stored a long time after hitting a deer. at 170K. It is in the process of being returned to service. An economics things versus buying new. It will be tagged with a watch on the oil use. Another words, check the oil with each fill up. Never assume it is okay each time. If you ever see the oil light come on. Shut it down or you will destroy the engine. Likely hood of this happening, pretty low. I saved a 87 Mitz Mirage that way years ago when it blew the rear main seal and it has been retired to a little old lady who survived cancer. Good final use for that car! I know, it was a lot of work to fix it, but I will do it for someone who will take care of an older car and use up the investment properly.
Final note. One of the reasons fleets buy a lot of the same makes is they can see what the first few units do and forecast what parts to keep available. You also know what to look for and when to replace. When that 97 came in, anything that came off to service that clutch if it so much had possible problem on it, it got replaced! At 240K, that was a few things like wheel bearings, steering rack boots and half shafts. Seals are cheap. That rear main, o ring, and oil separator plate are all under $50! If you ignore, you will be back in for ignoring it. It is cheaper labor wise to work that way and resolve many smaller issues as well. We know both from local dealer and our own experience those parts are a pain. We even advised the dealer to start replacing the O ring which they did not stock, because we confirmed it was dried out and leaking at 240K. I personally have even talked shop about these units with the service tech and confirmed these parts are a problem over 150K for sure. Clutch life, is if the driver carefully matches gears with engine speed, a good 200K based in the St. Louis area for a vehicle that gets a lot of highway use. I can see it being lower if someone is rough with it or stop and go driving. The way to confirm is to take a ride with the customer and observe how he drives. If he is rough, explain what is going on when he shifts rough and make suggestions on how to improve the life of the clutch.
Here it is a bit easier. You the driver screw it up, you pay for it! But when it comes to the average driver, your customer, few even understand how gasoline is burned! Problem is, few mechanics can explain how to improve driving. This is where an excellent customer rep comes into the picture. I can not stress the drive with customer after job is complete. I would do that even if repairing all rear seals. That drive will show you care about his pocketbook by explaining the proper way of shifting by matching up the gears with engine speed. The closer the driver gets with the skill, the longer that clutch will last. Yup, like I said before with our drivers, clutches last well over 240K and on the Subaru's fail because of oil leakage. They all had to relearn how to drive! I will also point out to replace that pilot bearing with a very good one. Come 240K, it is frozen up! Oh, those seals will not most likely make another 100K or more if they are not replaced. The cost is not worth going back in for.
#18450 of 19336 Re: Source of dirt on clutch plate?? [girlcarbuilder]
Dec 29, 2009 (2:38 pm)
"... Clutch life, is if the driver carefully matches gears with engine speed, a good 200K... lower if someone is rough with it or stop and go driving. The way to confirm is to take a ride with the customer and observe how he drives. If he is rough, explain what is going on when he shifts rough and make suggestions on how to improve the life of the clutch.... by explaining the proper way of shifting by matching up the gears with engine speed. The closer the driver gets with the skill, the longer that clutch will last... They all had to relearn how to drive! "
And you are not talking about Juan Fandango double-clutching. All the driver has to do is upshift slowly using fingers on the shifter, which gives the synchronizers time to work and allows the RPMs to fall to match to the next higher gear.
So many people shift with a pistol-grip hold on the shifter, hard and fast, followed by power on the clutch as they let it out, for a satisfying jerk. Even better, some change to a short-shift linkage to speed things up further. And some follow the same procedure when slowing down, cramming the shifter into each lower gear and popping the clutch out.