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Thread: Mystery Vanishing Coolant

                  
   
  1. #1

    Mystery Vanishing Coolant

    Vader seems to be loosing coolant at a rate of a cup every few months. I can note a slight antifreeze smell if I open the hood, but I cannot find any evidence of drips. Is it possible some is evaporating through the radiator cap? Is it worth replacing the cap as a 1st step?
    Bob Hopkins
    M3 1997 Black "Vader"
    911 1986 Red "Baron"

  2. #2
    Senior Member
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    I had radiator fluid loss from my 335 when on track; no evidence of any leak anywhere in the system. Best explanation is that there may have been air in the system, and upon evaporation the fluid level dropped.

    Maybe this is what's happening in your case.

  3. #3
    Senior Member mcoupemindy's Avatar
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    Replacing the expansion tank cap is step one for sure.

  4. #4
    Just to rule out the possiblity of a failing headgasket, if you haven't already done so, take a close look at your oil looks good and make sure t's not milky on the underside of the filler cap.

    Neil

  5. #5
    Quote Originally Posted by Neil View Post
    Just to rule out the possiblity of a failing headgasket, if you haven't already done so, take a close look at your oil looks good and make sure t's not milky on the underside of the filler cap.

    Neil
    I checked that 1st thing. My mother had a Corsica (POS) and it blew coolant into the oil. Ugly!
    Bob Hopkins
    M3 1997 Black "Vader"
    911 1986 Red "Baron"

  6. #6
    Senior Member
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    I had a coolant disappearance issue too. I cleaned the engine with a hand brush and drove for a couple hundred miles or so then checked to see if there was coolant anywhere on the engine or hoses. Turns out it was leaking from the stat housing, on the bottom where you can't see very well. BTW, I took off the lower protective plate to see the bottom off the engine which is how I found it.

  7. #7
    Senior Member Dirichlet's Avatar
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    Quote Originally Posted by Jenson Button View Post
    Vader seems to be loosing coolant at a rate of a cup every few months. I can note a slight antifreeze smell if I open the hood, but I cannot find any evidence of drips. Is it possible some is evaporating through the radiator cap? Is it worth replacing the cap as a 1st step?

    This was how my expansion tank issue started. I was losing cooling at a slow rate, and couldn't find where it was leaking. Summit Main cured that slow rate problem :P
    2000 323i
    1997 M3

    it was a beautiful day... the sun beat down
    I had the radio on, I was drivin'...

  8. #8
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    Bob,
    I'm on my 3rd radiator cap. They do go bad.
    The usual suspects do ocasionally leak, but usually leave a trail:
    thermostat housing
    water pump
    coolant tank
    hoses
    radiator (hope you've replaced this at least once!)

    I got an alumimum radiator for a permanent fix.

    Good luck,
    Joel Bossard
    ---------------------------------------------
    1998 M3/4, Silver driver
    2002 4X4 Dodge 2500 Cummins HO 6-speed hauler
    2006 VW Jetta TDI commuter

  9. #9

    Smile coolant leak

    I had the problem with my 1998 540i, where I would have to fill it up about a glass full of coolant every third or fourth day. Fairfax Service Center told me that it was a leak in my orginal water pump & replaced it. I also thought that it might be the expansion tank. I had the radiator replaced a few years ago.

    Good luck with your problem.

    Dennis Follett

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