Antifreeze drip 06 YZ450

9 replies to this topic
  • KillerHiller

Posted January 31, 2010 - 01:05 PM


I've got a slight antifreeze leak only when the bike is running. It's hard to see where its coming from but it's below the brake pedal area.

My wrenching experience is more with YZ250 2 strokes. The hoses all seem to be ok and sealed.

Which gasket would this most likely be? I'm guessing it's the water pump gasket but looking for some guidance. Maybe this is a common item for this bike.

I should check the manual too, but again looking for suggestions. It's loosing about a cup or 2 of fluid over the course of an hour.

Thanks in advance.


Edited by KillerHiller, January 31, 2010 - 01:07 PM.

  • bendover932

Posted January 31, 2010 - 01:26 PM


i would wipe/clean the underside of your waterpump housing/engine cases on the right side very well and dry...then start your bike and lean it against a wall or tree or somethin then get down on your hands and knees and look to see exactly where it is coming guess would be a bad waterpump seal which will dribble out the small hole located on he underside of the pump opposed to the gasket..but you will have to determine that by where it is coming from

  • KillerHiller

Posted January 31, 2010 - 01:32 PM


Good idea! Thanks for the quick response.

  • bendover932

Posted January 31, 2010 - 01:34 PM


no problem..keep us posted..good luck!

  • HNR_Engineer

Posted February 12, 2010 - 03:34 AM


It is the water pump seal that is leaking. If you look under the water pump housing there is a small hole where the cover meets the engine casing. It is there to let the water out when the seal is leaking.

It is east to fix. Buy a new seal. Then take off the water pump cover and remove the impeller. You will see the seal behind the impeller in the casing. Pop that one out and the new one in and reassemble.

I left out the draining the water etc but you will need to do that to, and fill it back up again.

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  • Polar_Bus

Posted February 12, 2010 - 03:58 AM


Pack a tiny bit of grease in the water pump cover weep hole. This keeps out mud grit from working it's way up into the housing. The grit is what can accelerate seal wear.

  • KillerHiller

Posted February 12, 2010 - 10:48 AM


Thanks Polar and HNR,

I'll order one up today!

I've got the 2moto snow bike kit on my YZ450. It's a frickin hoot! Don't want to blow her up.

Thanks again everyone!:ride::ride:

  • grayracer513

Posted February 12, 2010 - 02:03 PM


Pack a tiny bit of grease in the water pump cover weep hole. This keeps out mud grit from working it's way up into the housing. The grit is what can accelerate seal wear.

Let's be careful of that, shall we?

Blocking off the drip hole with anything even slightly substantial runs the risk of pumping coolant into the oil should the coolant seal leak substantially. It does not take a great deal of pressure to push coolant p[ast the oil sea;l form outside.

If you think it's really necessary to protect this hole from mud, tape a flap of rubber over it by the front edge of the flap only, so that the back edge hangs off the case a ways. This will keep splashes out while keeping the passage itself open most of the time.

  • Family Man

Posted March 14, 2010 - 07:16 PM


I was told if the seal is bad you need to replace the impellar aswell, true?

  • grayracer513

Posted March 14, 2010 - 08:31 PM


Not the impeller, the impeller shaft. And not in every case, although it is frequently necessary. When replacing the seal, look at the shaft to see if the seal has worn a groove in it that's deep enough to snag the seal as you slide it along the shaft. If so, the groove will prevent the new seal from holding.

Also, check for loose balancer shaft bearings while the case is opened up:

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