The water pump in your 2003 Chevy Cavalier circulates engine coolant from the radiator into the engine, where it absorbs damaging heat from the combustion process. The coolant is then pushed, by the water pump, into the radiator, where the heat it has absorbed is released into the air. When the water pump fails, overheating and severe engine damage can occur. The most common symptom of a worn water pump is a tell-tale leak from a small hole, called a weep hole, near the water pump shaft.
Disconnect the negative battery cable from the battery using an 8 mm wrench and lay it aside. Place a drain pan under the driver-side front of the Cavalier and open the drain valve located on the bottom of the radiator. Remove the radiator cap from the coolant reservoir and allow the coolant to drain into the drain pan.
Remove the serpentine belt, using a belt removal tool positioned on the tensioner pulley bolt to rotate the tensioner clockwise while sliding the belt off the alternator pulley. Disconnect the electrical connector from the alternator by pushing the release tab and then pulling the connector from the back of the alternator. Remove the two 13 mm alternator bolts, located in the front of the alternator bracket, using a 13 mm socket and ratchet. Add an extension to the socket and ratchet and remove the rear 13 mm alternator bolt located below the alternator bracket reinforcing rib on the back of the alternator. Slip the alternator from the bracket and lay it aside.
Remove the 10 mm water pump pulley bolts using a 10 mm wrench. Remove the 8 mm water pump mounting bolts using a socket, extension and ratchet. Use a screwdriver to pry the water pump from the front of the motor. Clean the gasket surface on the engine using a gasket scraper until all traces of the gasket are gone.
Attach the new gasket to the new water pump using gasket adhesive and install the new pump into the front of the engine. The gasket on the water pump in the Cavalier can be a little tricky to place, but it will only go on one way. Torque the water pump bolts to 18 ft-lbs. using a torque wrench.
Reinstall the water pump pulley and tighten the bolts securely. Reinstall the alternator and serpentine belt. Retighten the water pump pulley one final time with the belt installed to prevent loosening caused by vibration.
Close the drain valve on the bottom of the radiator and fill the engine with a 50/50 mix of fresh coolant. Remove the bleed valve on the top of the thermostat housing to vent air from the system. Reinstall the bleed valve when coolant starts to escape. Start the engine and add coolant to the engine as it is drawn from the coolant reservoir. Fill the reservoir to the full level on the reservoir, and reinstall the radiator cap.
