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Problems with coolant in trans oil

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So I've been rebuilding an old yz, turns out, after I replaced the bearing, and both rubber seals for the water pump, it's still getting a slight amount of coolant in the trans oil? Help plz. I've rebuilt tons of bikes and never had this happen after I fixed the water pump issue, can't be the head gasket so what else could it be? Pulled everything out and everything is exactly how it should be. Best

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Not familiar with Yamaha's set up, but did the water pump shaft have a groove worn in it where the seals ride?

Also, the seals have to face a certain direction.  I think the spring in the seal faces the liquid.

I would post this in the relevant Yamaha forum too.

Edited by WALKINGWOUNDED
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Not familiar with Yamaha's set up, but did the water pump shaft have a groove worn in it where the seals ride?
Also, the seals have to face a certain direction.  I think the spring in the seal faces the liquid.
I would post this in the relevant Yamaha forum too.

Not a groove but it did show some signs of wear

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I experienced the same scenario on Honda's. 

Honda shafts had to be perfect, or they would let liquid past the seals.

A head gasket would let coolant into the combustion chamber, and would burn with the gasoline.

Some would get past the rings too, but it would only get into the crankcase and still burn with the gasoline.

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Are the bearing pretty snug, or can you move the shaft around?
 

It's tighter than the virgin Mary

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If the shaft is tight in the bearings, bearing are tight in the housing, and seals are facing the correct direction, then I reckon replace the shaft.

Maybe pull the spark plug and kick the motor over, and make sure the shaft is not wobbling.

Or I suppose you cold start it for a brief moment and watch it's movement.

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If the shaft is tight in the bearings, bearing are tight in the housing, and seals are facing the correct direction, then I reckon replace the shaft.
Maybe pull the spark plug and kick the motor over, and make sure the shaft is not wobbling.
Or I suppose you cold start it for a brief moment and watch it's movement.

I'll just replace the shaft..... idk how tf this bitch is still leaking. Getting new suspension for enduro riding and a new carb and that bike is gonna be unreal
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