Water Pump

The water pump on the Imp is specific to the Hillman range.

The impeller spindle carries the driving pulley at one end and the fan hub at the other; it runs in two ball-bearings which are prepacked with grease and require no further lubrication. Retaining the water within the water space are two spring-loaded seals, located in each half of the pump body with their carbon- faced rings bearing against the machined end faces on the hub of the impeller. A small hole is drilled between each bearing and seal to allow any coolant that escapes past the seal to drain away, assisted by a dished washer positioned against the inner face of each bearing to deflect any water away from the bearing.

The water-pump and fan assembly can be removed after unclipping the rubber shroud from the fan cowling, then taking away the generator, as well as the three long bolts that retain the mounting-bracket assembly to the cylinder- block mounting. When dismantling, note the positions of all spacing washers and distance pieces. To dismantle the assembly, first remove the fan from its hub (3 bolts), detach the fan-cowl and pump-mounting brackets by undoing the four long bolts passing through the two halves of the pump body. Draw off the fan hub and pulley from their keys after un- screwing the self-locking nuts at each end of the impeller spindle. The two halves of the pump can now be separated by holding one half of the body steady and rotating the opposite half while pulling one from the other.

The bearings and seals can now be removed from each half of the body, noting that a circlip retains the thrust bearing at the pulley end. Carefully inspect the parts and renew the bearings if these show signs of roughness when rotated. Do not attempt to remove the impeller from the spindle. If the seal-mating faces at either end of the impeller are scored, renew the spindle and impeller assembly complete.

Fit new seals when reassembling. Start to reassemble by inserting the thrust bearing into its bore in the pulley half of the pump body, securing it with the circlip. Follow with the dished thrower, push the seal into its aperture in the body and insert the impeller and spindle assembly. Assemble the bearing, thrower and seal in the other half of the body.

With the mating flanges of each half of the body clean, coat the flanges with Shell Ensis Fluid 256, fit a new joint washer between the flanges and carefully bring the two halves of the body together. Temporarily bolt together while fixing the fan hub and pulley to the spindle.