By Gary Goms
Import Specialist Contributor
Since most water pump failures are caused by leaking seals, it’s important to inspect the cooling system for the presence of abrasive rust or sand particles. Rust, in particular, will cause early seal failure because of its abrasive qualities. Although rust is difficult to remove, it should be flushed from the system as thoroughly as possible before the old water pump is removed. Adequate flushing is aided by removal of the thermostat, which allows for a maximum water pump circulation rate.
In rare cases, the presence of dirt or loose core sand left over from casting the engine block may also cause repeated seal failure on water pump replacements, especially if the vehicle is driven on extended trips. Last, but not least, remember that many import vehicles require application-specific antifreeze to prevent corrosion in the cooling system and prevent premature water pump seal wear.
Before installing a new water pump, always compare the fan or belt pulley flange height with that of the old pump. If the height isn’t to specification, belt alignment may be adversely affected. To ensure the pump has the correct rotation, compare the impeller for similarity of configuration and size. Also, make sure that the old gasket has been completely removed from the engine block in order to maintain correct tolerances between the pump impeller and engine block mount and, of course, to prevent leaks. Before bolting the pump to the block, test for insufficient block clearance by holding the pump against the block and turning the impeller. When all dimensions and clearances have been checked, the water pump is ready for installation.
To prevent damaging the new water pump seal, make sure that the engine is completely filled with new coolant before starting the engine. With that done, always warm the engine until coolant circulates freely through the radiator and all air is bled from the system. Last, inspect for leaks and check the coolant level before releasing the vehicle to your customer.