How to Replace a Water Pump on a 1999 Chevrolet 1500

The water pump on your Chevy 1500 truck is the external engine component that keeps the engine coolant flowing through the cooling system, thus controlling the engine temperature. If the water pump fails, the coolant won't flow properly and the engine can overheat, causing serious engine damage. Changing the water pump on your 1500 is a job you can perform in your front yard in about two hours.

Instructions

Locate the cooling system drain and place the drain pan with the umbrella/extender under the drain. Turn the drain valve counterclockwise by hand to open and allow the cooling system to drain. Remove the fan shroud by turning the bolts counterclockwise with the ratchet or wrench. Set the shroud aside.

Loosen the clamp on the lower radiator hose to the water pump by turning it counterclockwise with the straight screwdriver. Push the drain pan under the front of the engine so it continues to catch the coolant from the radiator and will catch coolant from the lower hose and water pump.

Grasp the lower radiator hose where it connects to the water pump and twist it back and forth while pulling away from the water pump.

Attach the 1/2-inch ratchet adapter to the ratchet and insert the square drive into the square opening on the belt tensioner. Rotate the tensioner counterclockwise to release the tension on the belt. Remove the belt from the pulleys and set it aside.

Grasp a fan blade in one hand and hold it firmly. Rotate the four bolts holding the fan to the clutch and water pump by turning them counterclockwise with a 1/2-inch wrench or socket. Set the fan blade assembly, clutch and bolts aside.

Remove the clamp securing the short bypass hose to the water pump nipple by turning it counterclockwise with the screwdriver.

Remove the four bolts that secure the water pump to the block by turning them counterclockwise with the ratchet and socket. These are usually either 1/2 inch or 9/16 inch.

Grasp the water pump snout in one hand and firmly pull up and away from the block. Grasp the bypass hose by hand and twist the water pump until the hose comes off. Remove the water pump pulley.

Clean the gasket remnants from the mounting areas on the block.

Apply a thin bead of RTV to the water pump mating surfaces and apply the gaskets. Apply a thin bead of sealant to the block side of the gaskets.

Hold the water pump in place and reattach the bypass hose to the nipple. Hold the pump against the block and start all four bolts by inserting them in the holes and turning them clockwise by hand. Tighten these bolts to 30 foot-pounds.

Reattach the lower radiator hose and tighten the clamp to approximately 15 foot-pounds by turning it clockwise with the screwdriver. Tighten the clamp on the bypass hose the same way. Close the cooling system drain valve.

Slide the water pump pulley over the water pump snout, making sure the bolt holes line up. Attach the fan clutch and blade assembly by inserting the bolts and turning them clockwise by hand. Hold the fan in one hand while tightening the bolts to 25 to 35 foot-pounds.

Route the serpentine belt around all of the pulleys except the alternator pulley.

Attach the 1/2-inch drive adapter to the ratchet and insert the square drive into the opening on the tensioner. Rotate the tensioner counterclockwise to release tension, then slip the belt over the alternator pulley.

Attach the fan shroud by setting it in place and inserting the four bolts and turning them clockwise by hand. Tighten these bolts to approximately 20 foot-pounds using the ratchet or wrench.

Refill the cooling system with the new coolant. Start the engine and allow it to warm up. Top off the coolant level as needed. Check for leaks.