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Thread: '01 K1200LT Coolant leak at thermostat

  1. #1

    '01 K1200LT Coolant leak at thermostat

    I had a slight leak, replaced the O-ring. Still leakek. Took back apart, looked for cracks or burrs in radiator neck, found none. Broke one of the fingers/clips on the Thermostat.

    Installed a new thermostat and O-ring, but it still leaks around the O-ring. I'm sure it's around the O-ring since I can see it coming out from the clip.

    Don't know what I'm missing, or what I could be doing wrong. Has anyone else had this problem or have any suggestions?
    Last edited by richw; 01-19-2020 at 11:35 PM. Reason: Typos

  2. #2

    Crack in hose adjacent to???

    This is a wild guess.

    I'm totally lacking in mechanical knowledge.

  3. #3
    Quote Originally Posted by wildbears View Post
    This is a wild guess.

    I'm totally lacking in mechanical knowledge.
    Thanks, but I don't think the hose is the problem. I removed and inspected it, and additionally the fluid appears above the hose connection at the clip holding in the thermostat.

  4. #4
    Registered User
    Join Date
    May 2008
    Western Massachusetts
    Got any photos to help us visualize what your seeing?

  5. #5
    Quote Originally Posted by JeffDiCarlo View Post
    Got any photos to help us visualize what your seeing?
    I'll try to get a photo today. Still haven't resolved this, and looking for advice.

    Might even try some form-a-gasket or something similar.
    Parker makes something called "Parker O-lube" as well. I used grease as suggested, and hesitate to use anything "stickier", since it would be difficult to take apart.

    Edit: I used silicone grease - which is supposed to be water resistant. Parker O-lube is hydrocarbon resistant, and I suspect not better. I understand there is silicone "faucet grease" - perhaps that would work?
    Last edited by richw; 02-01-2020 at 12:18 PM.

  6. #6

    Still not resolved.

    I removed and re-installed the thermostat using "Dow-Corning 3" silicone diaelectric (waterproof, rated for high temp, and somewhat thicker than silicone grease or faucet grease).

    Still leaks. Unless someone has a better idea, the next step will be to remove the radiator to see if I can determine the cause.

    I tried to upload some pictures, but the upload failed. I'll try again later.

  7. #7
    Could it be the plastic/ceramic part of the thermostat itself??? Without seeing it, educated guess!!! After what you've said.....

  8. #8
    Registered User lkraus's Avatar
    Join Date
    Nov 2011
    Central Ohio
    The O-ring(6) forms the seal and prevents coolant leakage. The purpose of the grease is only to keep the O-ring from being twisted or distorted during installation. That distortion can create gaps that allow leakage, and any leakage will push grease out of the way.

    2006 R1200RT

  9. #9
    Clayshooter - I think that you are correct - something is cracked or warped as you suggest. I can't see anything with the radiator in place, and have not yet removed it.

    Larry - yep. The grease at best delays the leak for a short time, as you suggest.

    Still having trouble uploading a photo, but the diagram Lee provided probably shows it more clearly anyway. The leakage appears to be coming from the O-ring seal, but without removing the radiator I can't be certain.

    Thanks for the input. I'll keep you posted.
    Last edited by richw; 02-11-2020 at 12:27 AM.

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