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Old 01-13-2012, 12:26 PM   #31
jwegman
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Could you be blowing the new seal out if your breather is misbehaving and pressurizing the crankcase?
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Old 01-13-2012, 12:48 PM   #32
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I am fearing the worst. I have never seen an old seal just come right out. Something had to give for that to happen.
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Old 01-13-2012, 03:59 PM   #33
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I have the Cycle Works tool but I think I have used a block of wood to install at least one years ago. I prefer the tool. It is a mystery why you are having all this trouble.

I think you asked earlier if it's OK to run engine with out the trans on? I'd say it's OK. But you do have to have the flywheel on so you can't really see anything till you take it off again.
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Old 01-13-2012, 04:45 PM   #34
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The cracks in the block can be hard to spot - mine had one between the oil pump housing and the drain holes at the bottom of the rear main seal block area. I had the misfortune of changing the seal 3 times before I spotted the bugger. It breaks your heart. In my situation the crack would open up when the engine heated up and spew oil upward onto my crank shaft. The cause of the crack was BMW didn't clean up the drain holes at the bottom of the rear seal area and there was a stress riser that started it all.
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Old 01-13-2012, 05:11 PM   #35
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Originally Posted by supershaft View Post
I am fearing the worst. I have never seen an old seal just come right out. Something had to give for that to happen.
Actually, the silicone seals that were popular for awhile would pull out very easily with your fingers.
Most of them were white.
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Old 01-13-2012, 05:29 PM   #36
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This is a very interesting thread,BMWHacker is in the kind of fix that we all don't want to be but could find outselves in somewhere down the line.My first run in with a leaking crankshaft seal was in 1980 when my nearly new R100RS started leaking oil.The bike was a Demo that was out of warranty so I had to fix it myself.I didn't have the benefit of the Internet back then so I dove in at the deep end and fixed it without even blocking the crankshaft.Ignorance was bliss and everything worked out fine.

I digress,I wonder have you checked to see if the crankcase breather is plugged somehow,maybe hose crimped and building up pressure.If its not, why not pressurise the crankcase by using the vent hose to introduce a little air pressure back into the crankcase and then use the soap and water method on the crankcase to find any cracks and check the crankshaft seal to see if you get any air bubbles.It beats assembling the whole bike to ride it a mile or two to see if its still leaking.

John
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Old 01-13-2012, 06:48 PM   #37
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Originally Posted by Velocipede View Post
This is a very interesting thread,BMWHacker is in the kind of fix that we all don't want to be but could find outselves in somewhere down the line.My first run in with a leaking crankshaft seal was in 1980 when my nearly new R100RS started leaking oil.The bike was a Demo that was out of warranty so I had to fix it myself.I didn't have the benefit of the Internet back then so I dove in at the deep end and fixed it without even blocking the crankshaft.Ignorance was bliss and everything worked out fine.

I digress,I wonder have you checked to see if the crankcase breather is plugged somehow,maybe hose crimped and building up pressure.If its not, why not pressurise the crankcase by using the vent hose to introduce a little air pressure back into the crankcase and then use the soap and water method on the crankcase to find any cracks and check the crankshaft seal to see if you get any air bubbles.It beats assembling the whole bike to ride it a mile or two to see if its still leaking.

John

Loaded up my navigator and ran about 80 miles this afternoon. Still loosing some oil but it seems to be much less than what it was loosing before I dressed up the flywheel contact area. I'm going to run it more and see if things might seat themselves in.
I just replaced the long crankcase breather hose when I had the heads rebuilt, but I didn't check the breather valve operation.
If the oil loss doesn't stop then back in we go....I'll be much more observant if the third and final dis assembly is necessary. I never thought about seariously looking for cracks.
The old original seal was one of the earlier white seals, so maybe that is why it came out so easily.
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Old 01-13-2012, 06:50 PM   #38
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Actually, the silicone seals that were popular for awhile would pull out very easily with your fingers.
Most of them were white.
I don't think I have ever seen one of those. I don't see how you can get much better than the later type from BMW. They almost never leak from what I can tell. They are way, way better than the old rubber type. Same story with valve guide seals!!
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Old 01-28-2012, 08:09 PM   #39
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Ran the bike a couple hundred miles and the oil loss from rear of the engine was not getting any better. Started into things about noon today and removed the transmission again. (third times a charm?)
Decided to replace the new seal with another new seal and again check / replace the oil pump o-ring.

Below is the "new" seal installed a few weeks ago. The material is much darker than the replacement seal from BMW.
It is clean below but has stains and spots on it when it came out of the package. It never looked right to me from the start.




Below is the BMW replacement seal after installation. This seal material looks "healthier" than the new seal I just removed above.
I looked over the rear of the engine and couldn't find anything resembling a crack.






So with the offending seal removed, and a new one in its' place I reassembled everything and ran the bike a few miles this afternoon. I see no evidence of leaks.
I'll keep my fingers crossed and run some more miles tomorrow.



The culprit?....and his oil pump buddy....

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Old 01-29-2012, 08:51 AM   #40
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That seal looks too deep to me. I'm sorry. Check the edge of the flywheel where the seal runs. At this depth the seal will hardly leave a mark. The seal needs to be not driven all the way flush with the case.

Do it again.

You can't reuse the seal I think. Of course go ride it 200 miles to see if I'm right.

Charlie
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Old 01-29-2012, 09:14 AM   #41
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Photo might be deceiving. The seal is flush with the case. If it was out any further it would be sticking outside of the chamfered edges of the bore. I installed it at the same depth the original one lived. I got my fingers crossed.
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Old 01-29-2012, 09:47 AM   #42
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The seal looks fine to me as far as depth is concerned. I've installed quite a few. The only one that leaked on me was a N.O.S. silicone one that I got in a box of parts. (I was too cheap to buy a new one, never since though)
Since then, I've only used the current factory supplied teflon seal. Pre-formed with my fingers, installed dry where the seal contacts the flywheel, no pits or gouges on the flywheel etc.
Back in my VW tech days, when I was in VW factory training school, our instructor told us to check every case with a strong heat gun or propane torch for cracks. I have only seen a crack once or twice on BMW engines, but on VW cases it was a regular occurrence to have a cracked case. I think Pommie John from down under has posted a pic of his race bike cracked case.
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Old 01-29-2012, 11:14 AM   #43
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Well I don't know where I get this from. I searched around in records but could not find any authority to quote for you. So I'll have to take responsibility for this myself even thought the idea is not original to me.

The construction of the rear seal places the lip of the seal deeper than the top edge lined up with the case because of this most rear seals are found a little bit proud of the surface of the case and the recommendation is to install new seal to the same depth. That's fine if the seal being replaced is at the proper depth but if it has been replaced it may be at any depth somebody wants it to be.

What I noticed when I replaced the rear seal on my 1975 R90/6 is I could see the contact worn area on the flywheel where the lip of the seal rode and did it's work. It was not really worn but it was shiny because this spot was rubbed constantly by the seal. The shinny spot was on the very edge of the flywheel that needed to seal the oil inside the engine. I noticed the seal was only proud of the case surface by about 1mm so when I put the new seal in I placed it so it was at least 2 mm proud of the case surface. I of course have not been able to check the shinny worn spot to see if it is nicely away from the edge like I hope because after reassembly it has not leaked and therefore there is no need to take apart again.

I went and looked at the earlier pictures, noticed the original seal was installed flush. Don't have an excuse for myself. Hope this time works for you, I'm sure that doing stuff over and over is not fun, it's never fun for me. But if this has to come apart again in addition to looking for cracks with a propane torch also check the shinny area of the flywheel and see where that seal is ridding.

Charlie
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Old 01-29-2012, 12:32 PM   #44
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I went and looked at the earlier pictures, noticed the original seal was installed flush. Don't have an excuse for myself. Hope this time works for you, I'm sure that doing stuff over and over is not fun, it's never fun for me. But if this has to come apart again in addition to looking for cracks with a propane torch also check the shinny area of the flywheel and see where that seal is ridding.

Charlie
Me too, went through that two years ago on a K-bike teflon tranny seal. Could not reinstall at the same depth, it was leaking after benchtesting.

Had to open up the tranny to see the 'Shiny groove"....not an area on that one, an actual groove.

Careful measurements, remounted the seal so the lip wouldn't touch the "shiny area" , fine ever since. And looks like that same tranny seal had been replaced by many only to leak again shortly afterward.

Could the newer seal lip ride at a different depth nonwithstanding the depth of the outer part....very possible.

But interesting how they actually work/wear, some can extrapolate from that as to why they should be scrupulously clean and straight on installation:
http://www.ewp.rpi.edu/hartford/~peetrm/FWM/Project/Reference%20Papers/wear%20and%20friction%20of%20ptfe%20seals.pdf
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Old 01-29-2012, 01:47 PM   #45
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Originally Posted by wirewrkr View Post
Back in my VW tech days, when I was in VW factory training school, our instructor told us to check every case with a strong heat gun or propane torch for cracks. I have only seen a crack once or twice on BMW engines, but on VW cases it was a regular occurrence to have a cracked case. I think Pommie John from down under has posted a pic of his race bike cracked case.
My crack was almost invisible on my '94 GS - and I get paid for a living to look for cracks on gas turbines. This crack was so fine that it only opened up when the engine was hot and oil spewed from the oil pump housing onto my flywheel to be slung everywhere.
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