Yamaha TRX850 Enthusiasts Forum

Has anyone had their water pump apart?

Is there any longitudinal play in the shaft?

What is the impeller material?

How much clearance is there between the impeller and the volute casing?

How many of the cover bolts hold the pump in place? 3 of the 5?

Cheers

Martin

Yup, and will probably do it again soon. But I am not sure I can answer all Your questions...

Play, I can't remember

Impeller is metallic.

Volute? Not sure what measure You're after, radial or? (and above all, why?)

Beats me how many bolts that hold the pump, but I think You're right that some of them only hold the cover.

Thanks Hans

By volute casing I mean the pump casing.

Why? well.................................I have noticed that the 2 mounting points cast onto the web on the crankcase are missing on my bike and have been built up with Chemical Metal/JB Weld or similar.

So I'm concerned about the pump moving along the direction of the shaft, and possibly the impeller catching on the pump casing and destroying itself. If there is some movement in the shaft then hopefully the shaft would move with the casing..maybe not.

Maybe it doesn't matter.....maybe it does......there are no leaks.

I'm guessing that the pipe in the back of the pump casing is a push fit so the pump will hopefully be held in place by that - I have no faith in the Chemical Metal mounts. Certainly the pump cannot push back any further the other way because that pipe won't let it, as it's bolted to the block.

you could always fit an electric pump in line

OK, so I had to take the waterpump apart last night... Now I can add some more info. I also took some pics so that You can see for Yourself. I only had the mobilephone's camera with me, but I think You can see what You need...



So this is how the pump assembly, minus the cover looks like from the side. I measured the distance between the "shovels" on the impeller and the cover itself, and it seems to be ca 0,5 mm free room. There's one ballbearing inside, and a rather complex seal with a spring pre-load that keeps the water separated from the oil. The axle is kept in place with a locking circlip, but I couldn't feel much of a radial/axial play, nothing near the 0,5 mms at least.



Next pic shows the pump with impeller. Made out of metal.



This is where the pump sits on the engine. Ber with me, You'll have to tilt Your head 90 degrees left As You suspected there are 3 bolts that hold the pump assembly, and the extra two holds the cover only. (To be clear, upwards is to the left in the pic.)




This is the cover.

Thanks Hans, I owe you a beer.

So even if the pump tries to move, the rotor moves with it so can't destroy itself on the body.

Maybe it's fine held in place by just the bottom mounting bolt......we shall see!