Lexus 16100-29085 Engine Water Pump Assembly

A failure in the water pump can lead to engine damage due to overheating. To check if the water pump is working properly, squeeze the upper radiator hose while the engine is running and warmed to normal operating temperature. A pressure surge should be felt as the hose is released. Water pumps have weep or vent holes, and if there is a failure in the pump seal, coolant will leak from this hole. To find the hole in the water pump, use a flashlight to look through the space behind the pulley just below the water pump shaft. A slight gray discoloration around the weep hole is normal, while dark brown stains indicate a problem. If the water pump shaft bearings fail, there may be a howling sound at the front of the engine while it is running. Bearing wear can be felt if the water pump pulley is rocked up and down. However, do not mistake drive belt slippage, which causes a squealing sound, for water pump failure. Spray automotive drive belt dressing on the belts to eliminate the belt as a possible cause of the noise.