Mercury 9M6Z-8C419-A Water Pump

A failure in the water pump can cause serious engine damage due to overheating. If a failure occurs in the pump seal, coolant will leak from the front cover (four cylinder models) or the water pump housing (V6 models). Water pumps are equipped with weep or vent holes. It is possible to check the water pump weep hole using a flashlight. If a failure occurs in the pump seal, coolant will leak from the hole. Use the flashlight to find the vent hole on the water pump and check for leaks. If the water pump shaft bearings fail, there may be a howling sound near the water pump while it's running. With the engine off, shaft wear can be felt if the water pump pulley is rocked up-and-down. Don't mistake drivebelt slippage, which causes a squealing sound, for water pump bearing failure. A quick water pump performance check is to put the heater on. If the pump is failing, it won't be able to efficiently circulate hot water all the way to the heater core as it should.