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Discussion Starter #1
2002 K1200LT - Scratching my head here: I replaced the water/oil seal combo twice (with a new shaft). Each time, as soon as the engine oil is topped up, the oil begins to leak from the drain hole at the front of the engine. Instructions say "Insert shaft sealing ring (8) [the black rubber ring] into the guide sleeve of pressing-in tool BMW N0 116 723 and press in with the open side facing inwards." which is the same as shown here Water/Oil Pump Rebuild - The Internet BMW Riders

I pressed-in the oil seal lightly over the shaft using a socket and checked that it bottomed in the cavity with the open side facing the oil-side. The oil seal does not take very much force to press in. In fact, if the shaft is withdrawn, the oil seal it will drop out of the housing before the water seal is pressed in. The seal seems somewhat loose in the cavity which might explain why oil might be getting past the outside of the seal and draining out the drain. One post suggest running the bike to heat the seal. The drip is about 1 drop every 2-3 seconds.

TIA for any help on this.
-Kent
 

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2005 K1200LT
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While I have never done THIS job, if the oil seal can fall out then it is the wrong size as it should be tight around the outside rubber. I know Gordon just did this on a pump and maybe he will chime in and comment. Saddleman has done several of these.
 

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Yeah, the seal should definitely not fall out. I've rebuilt a lot of these and they all had a normal push to get them installed. Where did you get the seal, and what is marked on it? I can see if I have one and see what the marking is. Is the rubber still intact on the outer circumference of the seal?
 

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Yes, I just did this process and the seal had to be driven in on my pump so there seems to be an issue with the seals you are getting if it falls out. I got the Kit from Motobins 41149K plus a new impeller. I have no idea if it will leak. There was some corrossion on the shaft and I didn't think :( to look and see where the seal lip ran and if it was in the corrosion zone so it may or may not leak but the seal was tight enough to not fall out. The markings on the seal I removed were 12x25x5/7 and that matched the seal I installed.
171729


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Discussion Starter #5
It's a puzzle. I bought the seal here Water Pump Seal - BMW K Bike; 11 41 1 460 329 / EnDuraLast and it is marked 1 460 329 which matches the REALOEM part number (11411460329). Measures 25mm OD but it took very little force to push it into the cavity. I will try to run the bike and see if the leak stops. If not I'll try the Motobins version and install it with some sealant on the outer edge. Thanks chaps.
 

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Do you still have the first failed seal and can you post a pic of it? If it is that loose, I am not sure sealant will help but if you go that way, make sure and let it set well before attempting use. :)

Edit, do you still have the original seal to compare to the new?
 

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Discussion Starter #7
do you still have the original seal to compare to the new?
The original seal was torn up. The second seal measures 25.03mm--a fair bit smaller than you show--but it looks like all the others. I was just thinking that oil pressure into the open side might expand and seat it. Will ride it a bit and see. These two seals were from Euro Motoelectrics. Maybe they got a batch of undersize seals.
 

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Discussion Starter #8
WAIT! I read the dial caliper wrong. My seal is 25.20mm, at least as big as Gordon shows. I still have to run the bike.
 

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If your seal is not smaller than required, there is some other issue. You may have to go the sealer route when you install the next seal or possibly find another pump to rebuild. Mine is back on the engine now and I don't have the tools to measure the bore diameter for you to compare to. I would doubt running the bike would fix this as the seal has a metal frame under the rubber to support it which should require some resistance to install. If it just falls out, one side or the other has to be off.
 

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I measured a new seal at 25.15mm, and the bore in the pump housing at 25.0. If your new seal measures 25.20 and you install it without damage, then there's no way it should fall out.

There is a 28mm outer bore in the seal seat, and the seal has to be fully driven down into the 25mm section. The BMW tool holds the seal in a sleeve that sits in the 28mm part and slips it into the 25mm part without the chance to scrape the rubber off the outside. If your old seal has the rubber scraped off the outside, then that's what went wrong.
 

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Discussion Starter #11
Anton, I think you identified my problem. When I watched the videos, they drive the oil seal in with a socket. The Euromotor kit shows using a socket. I was not able to find a picture of the special tools 11 6 722 or 11 6 723 called for in the shop manual and using a socket seemed to bottom the seal in the cavity as I measured the depth. I guess not. Well one more try. BTW I rode the bike a few miles and it peed so much oil I thought I might not make it home. :-(
Euromotor includes a tool for pressing-in the water seal but nothing for the oil seal. It looked so simple . . . Thanks for the help.
 

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Both of the tools are pretty important. I think it would be way easier to describe the oil seal installer with a video. I don't have my GoPro here at the shop but I can do one tomorrow.

Years ago I started a tech article on this. Never finished it.

Trivia note for today: The F800 engine uses the same water pump seal as the K-bikes, but BMW only sells the complete $279 pump.
 

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The original seal was torn up. The second seal measures 25.03mm--a fair bit smaller than you show--but it looks like all the others. I was just thinking that oil pressure into the open side might expand and seat it. Will ride it a bit and see. These two seals were from Euro Motoelectrics. Maybe they got a batch of undersize seals.
With that kind of oil seal you must always have a bit of resistance when inserting the seal into the housing. The rubber coating of the seal must crush slightly when inserted. The kind of seal you are thinking about that works better under pressure is a hydraulic lip seal but even then it must be a very good fit in it's housing. You are better off measuring the bore of the housing that the seal pushes into rather than the old seal itself. If you measure the bore of the housing and the OD of the shaft that the seal goes over and then the thickness of the seal you can then take those measurements to a seal supplier and they should give you the right sized seal. Correct thickness is not as important as ID and OD. As a matter of fact if the shaft has a wear grove from running in the seal a slightly different thickness seal can give you a new surface for the seal to work on. You could also opt to Speedy Sleeve the shaft to renew the seal surface.
 

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Forgot the camera again today, but I realized that my draft article on water pumps is actually on my website but unlinked. I can't even remember how long ago I started it, and it's far from complete and probably not even 100% accurate. But it may be of interest to someone.


I will certainly add some details about the oil pump seal driver. Here is a pic of it. I loaded a seal into the sleeve and you’ll have to imagine how it goes into the 28mm middle part of the pump housing. Then the driver part pushes it out of the sleeve into the 25mm section. Also shown is the nifty end bullet to help the shaft go through the new seal without damage.

171751
 

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I will certainly add some details about the oil pump seal driver. Here is a pic of it. I loaded a seal into the sleeve and you’ll have to imagine how it goes into the 28mm middle part of the pump housing. Then the driver part pushes it out of the sleeve into the 25mm section. Also shown is the nifty end bullet to help the shaft go through the new seal without damage.

View attachment 171751
That is one fancy tool. I feel inadequate using a lowly socket to complete that job. ;)


171754
 

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A related FYI...

Below is the shaft as I found it in a '87 K100RS about 10 years ago when I rebuild the pump assy. due to finding coolant in the oil. Circumstances at the time prevented me from replacing the shaft so I reinstalled it with the new seals. To this day it is still functioning (97K miles) with no leakage. You can see that the surface the seal runs on (near the hole) was in good shape, the area exposed to the coolant on the other hand...

The weep hole in the housing was plugged with residue from the corrosion on the shaft. A good lesson in paying attention to cooling system maintenance... and a reference if you find yourself in a similar situation.

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That is as nasty as any that I've seen. The issue there is that the inner part of the water seal has to seal against the shaft. As far as I can tell measuring a few parts here, the blue sealant ring on the ID of the water seal ends up from 17.5mm to 20.5mm from the tip of the shaft. On the used shaft I have here, that is in the corrosion zone. The next 4mm (13.5 to 17.5 from the end) are covered by the smooth steel section of the seal inner part. On this shaft, that has some light pitting. I will draw up a better sketch in ACAD to verify those numbers, though.

I've never had to, but if the corrosion there is too bad you could probably add some sealant to the corroded area of the shaft before you install the water seal.

It's important to note that the BMW tool installs the water seal with about 1.5mm compression of the spring. That keeps the inner part from rubbing the outer part where they are swaged together. If you look at a seal you will know what I mean.
 

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Discussion Starter #18
Ah, the special tools! I can see why they're useful. Measuring off my old seals, the cavity for the two seals is 13.5mm deep and 27.5 mm wide at the oil seal. The 25.02mm OD oil seal is only held in the cavity by the the tiny 25mm ID ridge around the bottom. When the water seal is pressed in, there is a 1.5 mm gap between the two seals (13.5 mm minus 5mm thick oil seal + 7mm deep water seal).

So even if the the oil seal is properly pressed into the retainer ring, it still has 1.5mm to slip out of the shallow retainer with the water seal installed. Or futzing with the shaft after installing the oil seal could unseat the seal, Or, if you weren't paying attention like me, you could press in the water seal and not notice that the oil seal wasn't seated in the retainer.

Frankly, I don't know how the oil seal stays in place given that the oil pressure is pushing it forward via the oiling hole in the shaft. Seems like there should be a 1.5mm spacer between the two seals to to keep the oil seal seated.
 

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Sounds like something is wrong. Here’s a housing for reference. There’s the flat 25mm bottom section where the oil seal goes; it’s about 4.5mm deep just like the seal. Then there’s a small taper to the 28mm section which is also 5mm deep (this is the air gap). From there it’s 30mm wide for 8mm where the water seal presses in.

EDIT: The water seal only uses about 7mm of that depth, so there is about 6mm between the seals.

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I understand and wish I had a better recollection of what actions I took. I do seem to recall chucking the shaft up and dressing it. I wouldn't doubt I utilized JB weld (love the stuff) to buildup the corroded area and then machined it smooth. May have used some anaerobic sealer on the inner ID of the water seal as well.... another favorite go-to. Whatever I did it's still working...
 
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