Water pump flange adjustment

I’m just getting to the pulley alignment stage, and have noticed a slight discrepancy. The dynamo and crank pulleys are in perfect alignment, but the newly-rebuilt water pump pulley is slightly too far forward, by about 3-4mm, say 0.125". It’s not much, but there is a slight angle visible on the belt and straight edges across the pulleys prove it. The water pump is properly installed now with a new gasket etc.
The pulley flange is a press fit on the shaft. As it’s only (relatively) recently been pressed on, would it be worth trying to carefully tap it further on using a socket and hammer, very carefully? I don’t know what goes on inside, and I don’t want to risk knocking the flange, shaft and impeller assembly back against the front cover, or risk damage to the bearing. Otherwise it’s removing the pump and trying it in the press, but I can assess the position more easily this way. There’s no risk of creating inteference between pulley and front cover, there’s plenty of room.

Don’t tap it roger, use a press. It is acceptable/ necessary to move the pulley to get proper alignment

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I would second the press. Exactly which pump do you have?

Roger, you need to support the backside of the shaft when pressing the flange back (and make sure it’s only the shaft you support-don’t apply force to the impeller or it will move forward into the pump body). If you try to push the flange back without supporting the backside of the shaft, you will damage the pump bearing. So it will be necessary to remove the pump to do this. Just measure carefully to define how much you need to move the flange. Try to get it spot on, but if you err, push it too far rather than not enough as you can always shim it out if need be.

Thanks Steve and Phil, that’s what I thought and what I needed confirming. Mike, the pump is the original from my '55 140DHC, repaired and converted to ceramic seal.

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What is a source for the components needed for a water pump rebuild? Preferably US based. This for a 1953 120.

All sorted and done, thanks all.

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