2000 yz426f please help...

Hey all I have a 2000 yamaha 426f and I just had the cases replaced because of a broken bearing hold. Got it all back together and I have a couple of questions?

1. I know these things run hot but after a couple minutes of warming up the radiators are so hot they cannot be touched. Is it possible that the water pump is not working?

2. Cylinder head breather hose has a faint trace of coolant sometimes. I know that the radiator breather hose is down there as well but I swabbed the inside of the cylinder breather hose and there is a trace amount of coolant.

I have had two strokes for a long time and just got into four strokes.

If I could get any info at all it would be awesome.


One is normal. They heat up fast at a standstill.

Two could be normal. It depends on whether the stuff you're finding is coolant or atmospheric condensation. If it's coolant, that means it's in your oil, which is a) bad, and needs immediate correction, and :thumbsup: pretty easy to detect from examining the oil itself.

The oil, if contaminated, should have a milky, foamy appearance, and it the sump drain plug on the bottom of the trans is removed slowly, coolant shouls appear just before the oil.

Grey thanks for the advice I drained the oil and and it was a little milky I took a pic of it when I replaced the gaskets I did not replace the water pump seal at least that is what the dealer said. All the gaskets were brand new. What is your opionion and it looks easy to do the impeller seal.


That oil looks as if it has a fair amount of fine metal in it, but it doesn't look coolant contaminated. Is there any water at the bottom?

no water anywhere in it there was fine metal in the oil filter also it has new cases and clutch so are the small shavings normal?

Probably see a drop off in the metal content over the next two oil changes. How much time on that stuff?

5-10 mins just put it back together and noticed the residue, I took the rh case off and I am going to have the water pump seal replaced to be safe.

Unless you have blocked off the drain port under the pump, the water pump seal cannot leak into the oil.

I am just so scared about the breather tube leaking antifreeze, is there anyway to flush the motor oil out? should you be able to spin the water pump impeller and it keep spinning or should it have some resistance?

should you be able to spin the water pump impeller and it keep spinning or should it have some resistance?
Run that past again?

I think he is asking how much rotating resistance the water pump impeller should have.

Oh, I think so, too, but I didn't think the case cover was off the engine....

point taken :thumbsup:

the water pump is not free if you try to spin it, it will not keep spinning, is it supposed to keep spinning if you flick it or spin it. it will only spin if you keep spinning it. no bad sound coming from the bearing though.

fyi I have the case off the engine.

It has two seals on the shaft, so no, it won't spin freely on its own. It should feel smooth, but there should be seal friction.

thanks anymore ideals on the coolant in the breather hose

You're sure it's coolant?

yah for sure its green. were not talking a lot but its there

Run it for another hour, then recheck the oil condition and coolant level, etc. You can also have the cooling system pressure tested.

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