Weird stuff inside WR450 waterpump....Ideas?

Hi Guys,

During Stripdown of my 07 WR450 I came across this weird stuff inside the Cooling system, Specifically inside the water pump housing and on the impeller itself. It comes off quite easily and leaves a slight stain on the material underneath. The oil is spotlessly clean and the coolant was to, except for some floaties that were a similar colour...The only thing I can compare it too is some type of mould or algae or moss....

The bike has travelled well over 20,000 Brutal K's without missing a beat and has only ever been run on Yamaha Coolant and de-mineralised water.....It has not been ridden in 2 years and has been sitting inside a dry

shed for that time?? The motor feels strong and still kicks over 2nd or 3rd kick every time. The bike has been through some pretty hardcore conditions but I have religiously maintained it....Oil changed every 2nd or 3rd ride or 500K's, Oil filter every 2nd oil change and air filter cleaned every ride. Coolant is 2 years old and did 1 ride before being parked for 2 years....Water pump housing was removed approx 3 years ago to check impeller freeplay and this stuff wasn't there then....There is no evidence of this stuff in either of the radiators but a small amount in the waterpipe that connects to the top of the waterpump.

I must add that the Coolant overflow system was removed the first day I bought the bike and has been setup like a YZ with a simple drain ever since. I mostly ride in very wet muddy forrests with temperatures between 5 - 25c but have ridden in very hot dry areas too.

Anyone ever seen something like this before and any ideas what it is???

I'm looking forward to your thought's :devil:




My guess is the same as yours, Mold of some sort. Probably started growing during the 2 years it sat in storage. Was there much of this stuff found?


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