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Thread: Water Pump Seal Replacement

  1. #1
    Senior Member jiott's Avatar
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    Default Water Pump Seal Replacement

    After about 700 hours, my 912uls is starting to leak coolant from the weep hole below the water pump more than I would like. For a while it has just been a little leakage that was not noticeable in the coolant level. Now it is enough that I have to add about 1 cup or so to the overflow bottle in between 50 hour oil changes. My question is: has anyone replaced the water pump seal and what kind of a job is it? Special tools required? Does engine need to be removed?
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  2. #2

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    Default Re: Water Pump Seal Replacement

    I had the same problem,it does take special tools to change. Hal Stockman has the tools and the seals. He did mine when he did the big cam for me. I removed the engine and took it to him. I think you can remove the pump without pulling the engine. Then just send it to him. His # is 775 934 5714 Good Luck.

  3. #3
    Super Moderator Av8r3400's Avatar
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    Default Re: Water Pump Seal Replacement

    I pursued this with LEAF on my plane after seeing an occasional few drops of coolant at the weep hole.


    The advise I was given is that if it is only a small amount of coolant, replacing the seal is not warranted. Only when you begin to see engine oil coming from the weep hole is there a true problem needing repair. The weep hole will always produce some coolant.
    Av8r3400
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  4. #4
    Senior Member jiott's Avatar
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    Default Re: Water Pump Seal Replacement

    Thanks for the info from Leaf.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  5. #5
    Senior Member Wheels's Avatar
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    Default Re: Water Pump Seal Replacement

    av8r3400 is right on. I did replace the oil seal in a 912ul at 250 hours and I added the upgraded impellor per Rotax instruction. I got the tools on loan from Rotech research and I had to remove the engine to get to that component. Model IV. There is no other way as you need to remove the water pump and the ignition housing, line up the tool and use some force to install the oil seal.
    Its been 7 years ago. Anyway, the manual specifies that there is a tolerance for weep hole dripping. I was nowhere near the tolerance, I just panicked early in my mechanic carreer and replaced everything anytime there was a problem. Rotax loved me. You can find the tolerance in the 12-20-00 page 22 of line maintenance manual. Don't panic if there is a leak, the tolerance requires there to be no leak for 1 minute after shutdown. then it can leak, how much,,, I don't know, ask a tech to show you in the book, WAG just cost money.

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Water Pump Seal Replacement

    Thanks wheels, good info.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7

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    Default Re: Water Pump Seal Replacement

    Think I'll just keep fixing my leaks. Don' want oil showing up in my coolant on a long cross country trip and contaminate the coolant system. Not that big of a deal to fix. A leak is a leak not acceptable to me.

  8. #8
    Senior Member HighWing's Avatar
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    Default Re: Water Pump Seal Replacement

    I thought I had responded to this thread a week or so ago, but likely didn't touch the submit button. Many years ago with my first 912, it developed a slow leak near the coolant pump. I contacted the then Rotax representatives and was told to add a proportional amount of Bars Leaks which I did and no further problems. I mentioned proportional because of the low coolant quantity relative to what a car typically uses. Not sure if this is still accepted as a fix, but it worked for me for over 900 hours.
    Lowell Fitt
    Cameron Park, CA
    Model IV-1200 912 UL

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