04 450 coolant leak

4 replies to this topic
  • btray

Posted December 02, 2010 - 04:39 AM


Noticed some coolant leaking around the waterpump area. Grey is there anything in there I need to know about R&R of water pump seal? Is that the problem most of the time?

thanks Bill

  • grayracer513

Posted December 02, 2010 - 07:55 AM


There are a couple of points to bear in mind, but it's not a big job. Regardless of what anyone tries to tell you, do not be tempted to unscrew the impeller from the outside without removing the case assembly. If you try this, you may succeed, or you may break off the drive tab on the inner end of the impeller shaft. Drain the coolant, drain the oil, remove the right crankcase cover, and do it right.

Once the case is off, you'll see a pair of flats ground into the shaft next to the bearing. These are so that the shaft can be held with a 12-13mm wrench (varies model to model). To make it easier to handle the case and two wrenches all at once, rest the holding wrench against one of the case screws inserted from the inside into one of the case mounting holes. This helps quite a bit, especially if you're working by yourself, because the impeller can be quite stubborn. You will wonder about this at some point, so I'll just mention that yes, it's a normal right hand thread and unscrews counter clockwise.

With the impeller removed, everything pops apart very simply. Note which way the seals face; they will seem backward until you think about it. Pop the coolant seal out, then work through the shaft bore to drive out the bearing and oil seal. Inspect the bearing and replace it if you have any doubts. Look at the shaft carefully. If the shaft has a significant groove worn into it by the seal (not the square cut machined groove), the new seal will fail quickly. Use your judgment here. Minor grooves can be polished over by chucking the drive end of the shaft in a drill and spinning it in a piece of 320 grit wet with light oil or cleaning solvent. If you can catch a fingernail in the groove or it won't polish right out, replace the shaft.

The seals, as I said, appear to be installed backward because they need to be installed with the main sealing lips facing the fluid they seal against. The picture below will help you understand this. The impeller drive tab will seem loose in the balancer shaft drive socket insofar as how far it can be rotated in the slot. This is normal. As long as the diameter of the shafts match up well, and there isn't a lot of obvious wear on the tab or in the slot, it's OK. Otherwise, the reassembly is a simple little job most anyone can do.

The one really bad thing that you might find is a loose bearing on the right end of the balancer shaft. This bearing provides support for the inboard end of the impeller shaft, and if there is more than about .005" clearance up and down in the bearing, it can be bad news. On the '06 and later engine, the balancer bearings can be replaced with the engine in the bike, but on all earlier models, the cases have to be split.

RTFM, and Good Luck :thumbsup:

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  • btray

Posted December 03, 2010 - 05:42 AM


Thanks Grey, you're the reason why I found TT to be the best forum for getting it right the first time. You have a great Christmas and I am praying for your son's safe return.


  • grayracer513

Posted December 03, 2010 - 07:20 AM


Thanks for the thoughts and the prayers, but my son's not currently deployed. He was scheduled to be, but since the Rifle Team picked him up, that's typically a 2 year stateside thing, and the worst place he might get sent to unless something out of the ordinary happens is Quantico. Right now, he's working at Camp Pendleton, and he's home a couple of times a week. :thumbsup:

  • btray

Posted December 04, 2010 - 06:00 AM


That's great to have him close, appreciate his service to our nation, freedom isn't free it always cost.

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