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Thread: 1994 K75S Water Pump Case Sealant

  1. #1
    Slipster Slipster's Avatar
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    1994 K75S Water Pump Case Sealant

    Well after a nice 500 mile ride through the Winding Stair Mountains of Southeast Oklahoma I find my K75 dripping a little oil and anti freeze from the front weep hole. At 56,000 miles it appears to be water pump rebuild time. I ordered the seals, o-rings and spacers. What sealant does everyone recommend I should use between the water pump case and the engine when I button it up?
    Expect The Unexpected

  2. #2
    Rally Rat
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    Haven't had to do the water pump yet, but I used Yamabond 4 to seal up my valve cover and oil pan.

  3. #3
    3 Red Bricks
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    Not really recommended to use any sealant on the valve cover gasket.

    Yamabond or Three Bond 1207 on pump.



    Last edited by 98lee; 10-12-2012 at 04:47 PM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
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  4. #4
    Rally Rat
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    Quote Originally Posted by 98lee View Post
    Not really recommended to use any sealant on the valve cover gasket.
    Darned! Thanks, Lee.

    I did because there was already some there from previous owner service.

  5. #5
    Rally Rat
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    Not true. Sealant is supposed to be applied to the areas where the head meets the timing chain cover. There is often a pronounced step at this area and enough needs to be applied to fill this. It is usually neccesary to run a bead of sealant along the bottom run of the gasket. BMW uses a silicone-based sealant at the valve cover and at the water/oil pump.

    Resealing the pump requires a special tool, or some clever bodging. It's a real possibilty that you'll need a new impeller shaft, and you will also need a special spacer and water impeller. There should be a tutorial to show how this is done.

  6. #6
    Slipster Slipster's Avatar
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    Ok got the sealant thank you. I am now prepping the pump while waiting for the parts to come in. I have a question concerning getting the old Oil and Water seals out. I assume that the gear is part of the shaft and the seals will need to be tapped out somehow from the water side. Am I correct on this. Any methods that avoid harm when doing this part of the process?

    Learning as I go is a lot nicer with the great arsenal of forum members around
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  7. #7
    Rally Rat
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    Once you have the pump on the bench, the shaft willl pull right out.

  8. #8
    MearthA rdalland's Avatar
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    Quote Originally Posted by Slipster View Post
    Learning as I go is a lot nicer with the great arsenal of forum members around
    There are a bunch of Youtube videos that document the rebuild process. They were very helpful to me when I rebuilt my pump.

    There are a few threads on this forum as well, you might find some useful info if you search them out.
    ride what you've got; enjoy the road you're on!

    Reid - Stone Ridge, NY - MOA #69187 - Turbo Fluffy Motoclub - IBA #50182

  9. #9
    Slipster Slipster's Avatar
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    I got the gear and shaft off thank you. The water seal had completely self destructed and came out in pieces. The Oil seal was stuck like glue to the walls and base and had to be carefully scraped out. The walls and rims where the seals sit are smooth. The very bottom of the housing where the shaft enters is slightly pitted. Do I have to smooth these pits out with an emery cloth or something? The pits feel rough to the touch - not deep pits. I attached a pic to hopefully illustrate this better.
    Attached Images Attached Images
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  10. #10
    Rally Rat
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    You will need to clean that up. I use a Scotchbrite ball driven by a die grinder, but you may be able to use a cut down pad and a finger.

  11. #11
    Tom Mieczkowski mieczkow's Avatar
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    I went through this whole process a couple of years ago. I followed the recommendation of several folks on the forum and took my pump off and had my local shop (Hap's in Sarasota) do the rebuild. They ended up also replacing the shaft and impeller, which was pretty corroded.

    When it came to seating the pump back on the motor I did not have good luck with Yamabond at all. After two or three remove and reseal I had a small but persistent oil drip. A local BMW tech recommended black RTV. I used that and problem solved. After three years, no seeping.

    I also used a slight smear of RTV to cure a small drip from that troublesome little spot on the lower front valve cover - the spot where three different pieces meet. My bike had a definite feel-able ridge there. I used some emery cloth to smooth things out a bit and when replacing the valve cover gasket a little dab of RTV. No more drip.
    Tom Mieczkowski
    1987 K75S

  12. #12
    Registered User
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    I have used black rtv on the water/oil pump to motor joint multiple times with no problems. I think it is Permetex brand.
    Brian
    Brian

    86 k100rt, 78 r80/7

  13. #13
    Slipster Slipster's Avatar
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    Tomorrow the seals will be delivered along with the special installation tool and O-Rings.
    I'm filling my head with the installation procedure as described in this great article http://www.ibmwr.org/ktech/water-oil...rebuild2.shtml.

    Are there any other words of advice so I can run the best chances of doing this rebuild once with no problems afterwards on the bike ?
    Expect The Unexpected

  14. #14
    Registered User beemerguru's Avatar
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    If the shaft was corroded, that could mean trouble in the hole. Get the upgraded impeller assembly and maybe consider a lower mileage unit to rebuild off eBay or one of the local parts houses like Partz Haus or one local to you.
    Greg Hutchinson
    R80G/S (4) 633CSi with 450K mile
    '68 R60/2 '88 K100RS Special Edition
    http://gregsgssite.shutterfly.com/

  15. #15
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    Quote Originally Posted by Slipster View Post
    Tomorrow the seals will be delivered along with the special installation tool and O-Rings.
    I'm filling my head with the installation procedure as described in this great article http://www.ibmwr.org/ktech/water-oil...rebuild2.shtml.

    Are there any other words of advice so I can run the best chances of doing this rebuild once with no problems afterwards on the bike ?
    I also purchased the special tool. I do not recommend using a 3/8" socket driver extension for driving the water seal with the special tool. Mine went right through the center of the special tool and almost damaged the water seal. My second point concerns the oil pressure wire. Make sure you tape that sucker up against the crankcase well out of the way when mating the the pump back to the engine. I became so engrossed while reinstalling the pump assembly to the engine case that I forgot about the wire and pinched it; the wire is no longer available and the splice was not easy to do given where I had pinched the wire.

    Oh, I used Three Bond 1194 Liquid Gasket and never had a leak.

    Another thing, just like the video recommended, I used some grease when inserting the oil seal. Be aware that after you've completed the rebuild, the engine will warm up and that grease will melt and maybe exit through the weeping hole. Do not be alarmed if you see a leak by from the weeping hole and do not jump to conclusion too soon regarding your installation or mechanical abilities.

    Here's a picture of the goodies I ordered including the tool. Yes, I had a spare water seal as statistically speaking, I was doomed to thrash the first one given my inexperience. I would also recommend changing the long bolts inside the pump, mine were corroded and I should have replaced them but did not have them available.
    Last edited by ghyber; 04-06-2014 at 03:02 PM. Reason: poor grammar
    1993 K75S Mystic Red Pearl
    2007 K1200GT 997 Blue

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