How to Change the Water Pump on a 350 Chevy

Although the water pump plays an important role in the engine’s pulley system, the main purpose of the 350's water pump is to pull antifreeze from within the radiator, distribute that antifreeze throughout the engine, then route the antifreeze back to the radiator to be cooled. The 350’s water pump is a fairly simple design, consisting of a rotor and a seal. When that seal breaks, the antifreeze leaks out of the front of the water pump. Unfortunately, the 350’s water pump cannot be repaired, but replacing the water pump is fairly simple.

Drain the antifreeze from within the transmission by twisting the drain bolt on the bottom of the radiator with a pair of pliers or with a wrench. Insert the drain plug back into the radiator after the antifreeze has finished draining.

Loosen the alternator and power steering pump to remove their belts from the water pump pulley. Both the alternator and, if applicable, the power steering pump attach to the sides of the engine with two mounting brackets. At the top and bottom of each accessory is a single bolt, which holds the accessory to its brackets. Loosen these bolts with a wrench, then lower the accessory towards the engine to remove the tension on its drive belt, then lift the belt off of the pulley on the water pump.

Remove the fan blades and the pulley from the front of the water pump. The four fan blades are a single unit attached to the tip of the water pump with four bolts. Remove the bolts with a wrench, then pull the fan blade assembly off of the water pump. Lift the pulley off of the front of the water pump.

Disconnect the lower radiator hose from the passenger’s side of the water pump. The hose is attached to the pump with a single clamp. Turn the screw on the clamp in a counterclockwise direction with a screwdriver to loosen it, then pull the hose off of the water pump.

Remove the four bolts which hold the water pump to the engine and pull the pump away from the engine to remove it. Peel the two gaskets on the back of the water pump off of the pump.

Apply gasket sealer to each side of both water pump replacement gaskets, then place the gaskets against the pump. Press the pump into place against the engine, then install and tighten each of the pump’s four retaining bolts with a wrench.

Slide the lower radiator hose onto the water pump and tighten the hose clamp to secure the hose in place. Position the fan blade assembly onto the tip of the pump, then install and tighten each of the assembly’s four retaining bolts with a wrench.

Place the pump’s pulley onto the front of the water pump, then position both the alternator and power steering pump belts into the grooves of the pulley. Pull the alternator away from the engine to tighten its belt, then tighten both of the alternator’s retaining bolts with a wrench. Tighten the power steering pump’s belt the same way.

Wait a minimum of three hours for the gaskets sealer to dry, then fill the radiator with antifreeze to complete the replacement.