GMC 12685965 Water Pump Kit

A failure in the water pump can cause serious engine damage due to overheating as the pump will not be able to circulate cooled water through the engine. There are three ways in which to check the operation of the water pump while it is still installed on the engine. If the pump is suspect, it should be replaced with a new or factory-rebuilt unit. With the engine warmed up to normal operating temperature, squeeze the upper radiator hose. If the water pump is working properly, a pressure surge should be felt as the hose is released. Water pumps are equipped with 'weep' or vent holes. If a failure occurs to the bladder of the pump, small amounts of water will leak from these 'weep' holes. In most cases, it will be necessary to use a flashlight from under the car to see evidence of leakage from this point in the pump body. If the water pump shaft bearings fail, there may be a squealing sound at the front of the engine while it is running. Shaft wear can be felt if the water pump pulley is forced up and down. Do not mistake drive belt slippage, which also causes a squealing sound, for water pump failure.

To replace the water pump, begin by disconnecting the negative battery cable and draining the radiator. Remove the fan and spacer (if any) by unfastening the fan bolts from the water pump hub, ensuring that a thermostatic fan clutch stays in in-car position. Next, remove bolts that hold the radiator shroud to the radiator and lift it out of engine compartment. Loosen two mounting bolts for alternator, one is an adjusting strap bolt in slotted bracket, and other is a long pivot bolt located below alternator. Push alternator inward to relieve tension on drive belt; then remove drive belt from alternator and water pump pulleys. Remove water pump pulley from hub. Completely remove alternator strap bolt, swing alternator away from water pump, and take off thermostat housing-secured alternator mounting bracket at top of engine with one of water pump's bolts. Disconnect wiring at back of alternator using identifying tape if necessary for reinstallation later on. Remove alternator pivot bolt and raise it up off the engine. Release 2 mounting bolts for air pump and detach bracket connected to water pump. Pull air-pump away from engine , or take off air-pump pulley to access bracket bolts as necessary still equipped with power steering Loosen adjusting bolt and completely remove pivot bolt passing through water pump so as to swing it out of way without causing harm to hoses-connecting it to engine block .Disconnect lower radiator hose along with heater hose as well as bypass hose (if present) from water pump housing.Remove remaining bolts securing water pump against front side of engine block; lift off water pump from engine compartment; transfer heater-hose fitting from old one onto new or rebuilt unit.Clean gasket surfaces on engines; apply thin coat of gasket sealer to new gaskets ; install them on new pumps.Put this pump onto engine properly by bolting down but do not torque-tighten because power steering pump bracket and air pump brackets have to be reinstalled before which use water pump bolts for attachment. Proceed to install the engine components in the reverse order of removal, tightening the appropriate fasteners to torque specifications, and adjust all drive belts to the proper tension. Finally, reconnect the negative battery cable, fill the radiator with a 50/50 mixture of ethylene glycol antifreeze and water, start the engine, and allow it to idle until the upper radiator hose becomes hot. Check for leaks and, with the engine hot, add more coolant mixture until it reaches the bottom of the filler neck. Install the radiator cap and monitor the coolant level during the first few miles of driving.