Coolant leaking from head tube "99yz400f

4 replies to this topic
  • konadog

Posted February 15, 2008 - 07:27 PM


Sorry, I'm a newbie, Just got my yz400 and went for a ride, when I stopped there was coolant coming out from the tube which looks like it exits the head. Quite a bit of it. I just got a manual and was wondering if anyone has a idea??? It seems like a lot of coolant. When I got back home and checked the radiator, it was low

  • grayracer513

Posted February 15, 2008 - 07:51 PM


Is this the metal tube that connects to the coolant hose leading to the top of the radiator, or the small clear hose that is open at the bottom end?

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  • konadog

Posted February 15, 2008 - 08:14 PM


I just read the manual and it is coming from the cylinder head breather hose.
frothy looking but definitely liquid and smells like coolant???

  • grayracer513

Posted February 15, 2008 - 08:39 PM


Sounds like the head gasket is gone. It's not usual to have a small amount of condensation gather in this tube in moist climates, but coupled with coolant loss, it isn't a good sign. If coolant is actually getting in the oil, it will be obvious by looking at the oil itself. Remove the drain plugs and watch for any coolant coming out as they are first removed.

  • konadog

Posted February 15, 2008 - 08:55 PM


That's what I was afraid of. Thanks for your help. I'll drain the oil and have a look.

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