The water pump circulates the coolant in a GMC Sonoma engine. If the pump starts to emit a high pitched squealing sound, then the bearing is likely shot and you need to replace the pump. Another sign that the bearing is gone is if you are able to wiggle the pulley. The pump may also leak water through the weep hole. It takes about an hour and a half to replace it, since you have to remove the fan and the shroud.
Remove the negative cable from the battery using a wrench to loosen the terminal nut. Open the valve on the bottom of the radiator using a wrench and drain the engine coolant to the drain pan. Relive the tension of the serpentine belt by loosening the idler pulley with a wrench. Remove the belt from the engine.
Remove the fan shroud using a wrench to loosen the bolts. Remove the fan and fan clutch assembly, using a wrench to remove the bolts. Remove the water pump pulley using a wrench to remove the bolts. Remove the hoses from the water pump using a screwdriver to loosen the hose clamps.
Remove the retaining bolts from the water pump using a socket and ratchet. Pull the pump away from the engine block. Clean any remaining gasket material from the engine block using the scraper. Place a new gasket and water pump on the engine block. Secure it by tightening the bolts with the socket and ratchet.
Attach the hoses to the water pump and tighten the hose clamps with the screwdriver. Attach the water pump pulley to the pump and tighten the bolts with the wrench. Install the fan and fan clutch. Tighten the fasteners with a wrench. Install the upper fan shroud and tighten the bolts with a wrench.
Check to make sure the valve on the bottom of the radiator is closed. Refill the radiator and reservoir with engine coolant. Connect the negative cable to the battery and tighten the nut with a wrench. Start the truck and check the work area for leaking.
