GPZ 900R / 1000RX etc water pump overhaul


With the pump fully dismantled, we can now turn our attention to renewing everything to complete the overhaul.

Naturally this will be the reverse of the dismantling process, but there are times when special attention must be paid in order to ensure that the overhaul is succesful.

First we must ensure that all traces of corrosion are removed, and that the pump casings, and the impeller are fully cleaned, and rust free. Then, and only then can we move onto the reassembly process.


Press a new bearing into the pump side of the shaft. This can only go in so far, and it is a simple task to drift it into place using a suitably sized socket.

Refit the second bearing from the shaft side of the pump,

Refit the ceramic plate, and it's rubber seat to the rear of the impeller.

Nb It is crucial that the ceramic plate is not scratched or damaged during it's installation.

Here we can clearly see both the new plate, and it's new rubber seat.

We must now fit the mechanical seal to the pump housing by fully pressing home the cupped seat (A). It is possible to fit the mechanical seal as a complete unitbut if it has been split in two once the seat is in place fit the spring loaded plate assembly (B)

Be sure to fit the correct size mechanical seal they are either 32mm or 35mm when measured across the widest point (lip). Seal details are here

We can now refit the impeller into the pump housing. Here a large vice is used to slowly press home the impeller through the two bearings..

Remember that as the impeller nears it's final position, the end of it's drive shaft will begin to protrude out of the end of the water pump shaft housing.


Do not try and press home the impeller without allowing room for it's drive shaft to protrude from the end of the pump housing


Press the impeller home. As a guide the end of the driveshaft should protrude approx 14mm from the end of the pump housing. The governing factor is that it must be pressed home sufficiently to allow the circlip to be replaced.
Replace the circlip and if the pump is stiff to turn lightly tap the shaft end until the circlip lies against the bearing.

Replace the oil seal. Ensure that it is fully home.

Replace the O ring around the pump shaft.

Refit the water pump gasket, and bolt the two halves together.

Refit the water pump bleed screw and renew the alloy gasket.


That's it your pump is now fully overhauled, and ready to be refited to the machine.