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KTM 390 Duke Engine Failure

Discussion in 'Technical and Troubleshooting Torque' started by malJohann, Feb 10, 2016.

  1. So, my bike overheated the other day, and the safety shutoff kicked in. Got it towed and inspected the engine to try find the problem, milky oil in the sight glass and the level is higher.

    So my google fu says its either water pump seal failure, top gasket failure, cracked top or cracked block. Can anyone think of anything else? Best is to probably start at the water pump with a service kit, right?

  2. There comes a point where it's better to pay a professional to diagnose the actual problem than throw $ , time and parts trying to fix what may not be the problem, my 2c worth
    • Agree Agree x 4
  3. Sure, but I haven't had a job since October, so trying to fix it myself first? I understand what you mean though.
  4. Self serviced since 7,500km and has aftermarket piggyback ECU and air filter, also found it has a crack on the side of the airbox after the filter, so not sure how a warranty claim would pan out.
  5. How much coolant is left in the system? i.e. did it overheat through insufficient coolant?
    If there's still a lot of coolant left, it's probably not just the seal.

    (On the bigger KTMs, water pump seal failure typically leads to low oil pressure before overheating.)
  6. Little to no coolant in the radiator, but strangely the coolant filler tank remains full. The oil level has risen significantly.
  7. Put it back to standard and do a warranty claim on it
  8. Despite ethical problems with this, it hasn't been dealer serviced?
  9. It could be a number of things so on so on.

    correct diagnoses is key and will save you money!
    This is where you need a real mechanic that can propaly diagnose the problem.
  10. There is more then one way for coolant to get in your engine not just the water pump seal!!
  11. Did you read the bit where I outlined four possible problems, the water pump being just one of them?
  12. Yep sure did!
    Google is not a mechanic and can't diagnose your problem !
  13. Well, if the rad is nearly empty a lot of coolant is getting out somewhere, and if it's in the oil there's some kind of jacket failure.
    I suppose you've looked to see what's coming out of the exhaust? A gasket failure or crack would tend to see coolant escaping that way.
    • Agree Agree x 1
  14. Fingers crossed it's just a head gasket. Cracked block would not be cool. Sorry I can't be much more help than that but I've got my fingers crossed for you that its just a head gasket.
  15. Doesn't have to be.
  16. but self servicing would be hard to argue (as opposed to an lisenced mechanic). Might be worth a try.

    If you are doing it yourself, then it seems the water pump would be the first thing you check, as it's pretty easy to do so.

    After that you are pulling the head off.

    A crack after the airflow meter may cause a lean out, which can burn head gaskets.
  17. #18 malJohann, Feb 10, 2016
    Last edited: Feb 10, 2016
    Feeling slightly sheepish right now, went and did a coolant system flush, rad was near empty, and since the last time I started it, the filler tank was now empty too. Drained about 500ml old coolant out the system, filled the radiator, then the filler bottle to the max line, and idled it for fifteen minutes. Everything worked as expected, and no visible smoke at all. Went for a ride and noticed coolant coming out the overflow without overheating problems, came back to check and now the coolant in the filler tank was above the max line. Coolant expansion? Other than that, its now running 100%. :)
    • Like Like x 2
  18. Currently thinking this is the issue, may try bathroom silicone sealant as a temp fix to diagnose.
    • Informative Informative x 1
  19. so what happened to the water in the oil?