Polish seal surfaces with wet and dry abrasive for a better seal. A lathe can be used to rectify faults with the pump body, such as a warped flange. If the original water pump was garage door opener 2001 tahoe with a grease nipple remove inner bearing shields on modern bearings.
The cross section diagram shows clearly the position of the required clearance and the seal details. Putting the pump together is fairly straightforward, with only four components the bearing assembly, a seal, an impellor and the fan belt pulley that was removed from the pump. The bearing garage door opener 2001 tahoe has a length of shaft at each end. The shortest faces forward on to which the pulley is fitted, the longer length has the seal and impellor fitted after the bearing assembly is pushed into the housing.
I chose to push the bearing assembly though from the back of the pump, but it will not matter which way it is done, as long as the bearing outer shell ends up flush with the pump housing at the front. When pushing the new bearing assembly in, pressure should not be applied on to the end of the shaft, as this may put undue strain on the bearing components; pressure should be applied to the outer bearing sleeve. It didnt matter on the old bearing that was removed as it was destined for the garage door opener 2001 tahoe bin. If you are rebuilding the whole engine, it will be found that the old gudgeon pins holding the pistons to the con rods are of the correct size to not only fit over the projecting shaft, but also have a suitable outside diameter to push on the outer bearing sleeve and have a clearance from the seal housing. If you are only doing the water pump then a suitable piece of tube will need to be found with similar dimensions.