GPZ 900R / 1000RX etc water pump overhaul

By Craig Davies The GPZ Zone

Acknowledgements - Neil Perkinton.

Although the GPZ 900R is famed for it's temperamental cooling system, it is fair to suggest that the water pump is robust, and certainly up to the job. However it can occasionally fail, and it is the presence of drips of either oil, or coolant from the water pump's weep hole that signals a failing pump.

There are two seals in the water pump, an oil seal keeps the oil in place, whilst a mechanical (rotating ceramic disc) seal keeps the coolant in place. The water pump is driven directly from the oil pump, and should one, or both of the seals fail, then the drain hole will prevent cross-contamination of oil & coolant.

Technically, this is a simple task, but it does require some care, with that said, it is well within the capabilities of most home - DIY mechanics.This article is aimed at guiding the home mechanic through the process of overhauling the Kawasaki water pump from the GPZ 750R, GPZ 900R & GPZ 1000RX. It may also apply to other models, but as yet, claims to this affect cannot be substantiated. No specialist tools are needed but access to a large vice, or preferably a hydraulic press are essential. You will of course require a water pump overhaul kit which can be purchased online from The GPZ Zone . At the time of writing the cost of purchasing an overhaul kit is around £120 less than the cost of a new pump. - An attractive saving! The task should take even the slowest & most cautious operator - no more than a few hours.

IMPORTANT - PLEASE READ

There are 3 different pumps fitted to the GPZ 900R each differing very slightly from the other. Externally it is not possible to tell these pumps apart, however if you prise out the oil seal 4th & 5th photo down) you should see a circlip which retains the bearings. If your pump does not have this circlip it CANNOT be overhauled. This is because this type of pump uses a cartridge bearing, and any attempt to press it out will almost certainly destroy the pump casings. If there is no circlip - you will need a new pump!

If you see a circlip, then your pump can be overhauled using the information in the following pages.

Here we see the water pump removed from the machine, unscrewing the two bolts will allow you to split the pump in two.

The two other bolts have been removed whilst removing the pump from the machine..

Splitting the pump in two exposes the impeller.
Remove the water pump gasket, and thoroughly clean out the groove in which it sits.

Remove the oil seal that sits inside the pump housing. In some cases this seal may actually have become unseated (as shown). This causes oil to seep from the water pump's drain (weep hole)

In this image you can also see that the water pump shaft O ring has been removed. (Groove)

With the oil seal removed, it is possible to access the circlip which retains the shaft & bearings.

Using circlip pliers - remove the circlip.

Now we start to get a little bit more involved!

We must now press the Impeller shaft out of the bearings. A hydraulic press is perfect for this, but the same result can be achieved with a large vice.

A hammer can be used, but there is a small risk of damaging the end of the impeller shaft.

Notice in this picture how the impeller is free to travel out of the pump, and is not obstructed.

Here we see the impeller being pushed out and clear of the pump.

Eventually, as it clears the pump, the impeller drive shaft will disappear into the bearings, at this point we must use a drift to gently tap out the impeller.

Using a press is preferred but generally there is little resistance by now, and a hammer & drift is sufficient.

Eventually we can withdraw the impeller & shaft from the pump.

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