KTM 450 EXC Coolant Leak - HELP?!

Discussion in 'Thumpers' started by BgDadddy, Nov 13, 2012.

  1. BgDadddy

    BgDadddy Big Dufus

    Joined:
    Sep 10, 2008
    Oddometer:
    1,829
    Location:
    Knoxville, TN
    Hello all,

    **DISCLAIMER** I know nothing about KTMs, and I'm not that great of a mechanic. **

    I'm trying to figure out where a coolant leak may be coming from. When you start the bike, there is no leak. As the bike warms up, the radiator on the shifter side heats up, the one on the brake side does not. I imagine there is a thermostat in there somewhere.

    Finally, once the bike (and the left side radiator) gets hot, suddenly coolant starts leaking from somewhere on the bottom of the radiator(s) directly onto the head pipe. Tons and tons of white smoke coming off the pipe.

    Is there a thermostat down there that opens up or something that would cross over to the other radiator? What could be leaking down there only when the bike gets hot? :ear

    Thanks.
    #1
  2. wsmc831

    wsmc831 Been here awhile

    Joined:
    Jan 25, 2006
    Oddometer:
    900
    Location:
    Central Oregon
    sounds like the water pump failed.

    What year is the bike?
    #2
  3. dualsportride

    dualsportride Been here awhile

    Joined:
    Dec 4, 2011
    Oddometer:
    263
    Location:
    Plainfield, Indiana
    I can't get the image to post so here is a like where I posted it.

    Cooling System

    Here is an image of the cooling system part #32 is the thermostat which open at 70 degrees I believe. The water comes out of the motor and then to the left "shifter side" until the thermostat opens then goes into the right side. If I'm incorrect someone please correct me. As far as a leak goes my guess is the overflow tube that is connected just under your radiator cap is dumping onto your header if you can find any other leaks. I would check that hose it should be clear to see where it is going and hope that is where the leak is and not a radiator leaking. If you can take out your thermostat to see if that solves your issue if not water pump or radiator cap is where I would go next. Also keep in mind it doesn't take long for these bikes to start to over heat with no air flowing. If you have any more questions contact me on here or at www.usdualsports.com
    #3
  4. motorking99

    motorking99 n00b

    Joined:
    Nov 14, 2012
    Oddometer:
    1
    Hello,
    I am the tech manager at Prestone Antifreeze/coolants. You can borrow a coolant pressure tester from Advance Auto parts or Autozone and pressure test your system to see where the leak is coming from. In the past, an automotive tester wouldnt work on a motorcycle due the radiator cap size difference. Now, most cars have much smaller caps so it is likely you will find an adapter in the kit that will work. This will allow you to pressureize the system to simulate running conditions and find the leak. Good luck!
    BTW- Prestone 50/50 extended life coolant will work fine in your KTM.
    #4
  5. BgDadddy

    BgDadddy Big Dufus

    Joined:
    Sep 10, 2008
    Oddometer:
    1,829
    Location:
    Knoxville, TN
    I appreciate everyone's feedback. I'm going to tinker with it some more over the weekend.
    #5
  6. Wandering Dane

    Wandering Dane We are the luckiest guys

    Joined:
    Jul 9, 2005
    Oddometer:
    426
    Location:
    Lone Tree, Colorado
    I've experienced coolant leaks on my 520 EXC:

    1. The simplest on my bike was the radiator cap not sealing properly. For some reason on my bike, the cap seals perfectly in one position, 180 degrees off and it leaks. But only when the engine gets hot as in slow, steep going. The coolant simply drains out of the overflow tube. White smoke = coolant on hot exhaust header.

    2. Be sure that all the hose clamps are tight, and then tighten the clamps one more time. Hoses WILL leak if the clamps are not tight.

    3. Water pump seals: early failure will manifest itself along the lines that you describe.

    Good luck.
    #6