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I have the cover off my water pump right now to change the rubber gasket. I was cleaning the impeller off and noticed that it doesn't turn, only moves a bit in each direction. Is it supposed to turn, or only when the thermostat kicks on?



It was a pain in the butt getting the cover off, I kind of want to make sure everything is functioning properly before I put it back on. I am planning on using a small amount of gasket sealer, as the cover has a tendency to leak I've noticed. Good idea, bad idea?
 

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Are you saying that the impeller doesn't turn when the engine is rotated? The impeller is mounted on the cam shaft, you should not be able to move it by hand. But it certainly should rotate when the engine spins. The thermostat has nothing to do with the operation of the impeller.



If I remember the gasket on the pump cover is a big O ring type seal. They normally don't require a sealant, but you do want to clean the O ring and parts up. Maybe your leak was from the weep hole?
 

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The weep hole is a small hole in the engine block just below the coolant pump and a little to the left of centre.



If you look at the coolant pump as a circular centre with two wings you will see the weephole under the left "armpit"



If your coolant leak is in fact coming from this hole your mechanical seal {which is behind the impellor} is actually your culprit and will need to be replaced.
 

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If you already have the cover off anyway it may not be a bad idea to go ahead and change that mech seal using the Shep way, just replace the rubber bits. If you use the yamaha seal it's only $15 or $20
 

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you can do that if you use the "SHEP" method - ie replacing just the rubber cup, if you need to replace the whole seal you need to remove the rear cover - and that is engine out time.
 

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What ever you do don't remove the metal cup. Just stick a pair of needle nose pliers in there and pull out the rubber seal.
 

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Yes, the impeller moves a bit from side to side, I'd say a quarter inch or so each way, but I'd have to check to see how much for sure when I get home tonight.
The splines on the impeller or camshaft may allow some play in the impeller if they are worn some. If when you move the impeller you can see the fan on the front of the engine move also then that would indicate that the camshaft is moving too.
 

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Yes, the impeller moves a bit from side to side, I'd say a quarter inch or so each way, but I'd have to check to see how much for sure when I get home tonight.


I'm concerned at this as well

I may be wrong but I dont recall ever having any play on the impellor

except when I found one with stripped splines.

As I said maybe I'm wrong and perhaps there are a few camshaft positions where you

can wiggle it a bit but a look at the splines will help here
 

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I'm concerned at this as well

I may be wrong but I dont recall ever having any play on the impellor

except when I found one with stripped splines.

As I said maybe I'm wrong and perhaps there are a few camshaft positions where you

can wiggle it a bit but a look at the splines will help here


There is another possibility,,but I will wait til we see if the splines are worn/stripped.
 

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The splines on the impeller or camshaft may allow some play in the impeller if they are worn some. If when you move the impeller you can see the fan on the front of the engine move also then that would indicate that the camshaft is moving too.


The impeller shouldn't move even if the splines are worn, since it's tightened by the dome nut. Anyway the splines should never wear since there is no movement at this point during operation.
 

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I've seen and heard of stripped splines a few times

Maybe they shouldnt wear, but they do.

Its probably caused by 'operator error' but it happens



Mans abiltiy to bugger things up is boundless
 

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have i got this correct....

irrespective of the impeller splines being worn or not.you should not be able to turn the shaft.unless,

1.the tension on the chain has dissapeard

or

2.the shaft,origionally built in two pieces,has gone back to being in two pieces.
 

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have i got this correct....

irrespective of the impeller splines being worn or not.you should not be able to turn the shaft.unless,

1.the tension on the chain has dissapeard

or

2.the shaft,origionally built in two pieces,has gone back to being in two pieces.
Either way unless there was some slack somewhere,,I would think it would be hard to turn the impeller by hand.



If there was slack in the chain, the cam would still have to be in a position where it could move easily, unless the splines are worn.



Your second possibility is what I was thinking about in my post above.
 
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