The water pump carries all the coolant through the hoses, engine liners and radiator in a continuous cycle. The water pump impeller is responsible for constantly rotating to keep the coolant flowing at a rapid pace. When the water pump leaks or fails completely, the engine can overheat, which can cause catastrophic failure of all systems, including plastic components, sensors, hoses, head surfaces and bearings. Replacing a Chevy’s water pump can be a satisfying challenge, if the repair person knows what to do with a few tools on hand.
Disconnect the negative battery terminal. Find the fan shroud on the front of the engine. Remove the top four bolts from the shroud and lift it off. If the air conditioning (AC) hoses restrict movement space, remove the AC compressor bolts and lift the AC unit and hoses so that the top guard comes off.
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Find the auto tensioner pulley where the serpentine belt attaches to it. You’ll find a small 3/8-inch hole near the bottom. Insert the 3/8 wrench into the hole and push to your right, this will reduce the tension on the belt, allowing you to slide the serpentine belt out.
Place a large open end wrench on the pulley shaft nut to hold it stationary while you use a wrench to remove the fan bolts; there should be four, but only remove two. Wedge a flathead screwdriver between the two remaining bolts and loosen the large shaft nut, which will remove the fan. Then remove the remaining two bolts.
Make sure you have removed the water pump pulley bolts, then pry the pulley out until it slides off the shaft. Use the screwdriver to wedge in the slots that hold the lower fan shroud in place. Pull the bottom shroud out from the bottom up through the top. This gives better access to the lower bolts on the pump housing.
Drain the radiator by loosening the lower tap valve on the lower left side of the radiator (facing the front of the vehicle). Use a 1/4-inch ratchet to turn it approximately 90 degrees. Drain the old fluid into a pan. To tighten the faucet valve, you will need to first push in and then turn in the opposite direction to close it.
Use the channel locks to bend the spring clips on the heater hoses to remove them. Pull the heater hoses free and away from the water pump. Depending on the clamp (either screwdriver or pliers), loosen the clamp on the lower radiator hose and loosen the hose by twisting and pulling it out at the same time.
Use the correct size socket and extension to loosen the two bolts on the left side water pump housing. You can see them directly under the alternator, just above the lower radiator hose connection. Loosen and remove the two right bolts, they are under the AC compressor and the compression pump clamp. Pull the clamp free from the block. Use the gasket scraper to clean the surface of the block where the pump attaches to the block.
Rub gasket adhesive on the mounting surfaces of the new water pump and compress the new mounts into it, making sure you line up the bolt holes. Place the four mounting bolts into the holes in the pump housing, tilting the housing at an angle where they will not fall out. Carefully align the new water pump with the block and begin tightening the bolts with your hands only. Be sure not to move the pump with too much force while aligning it, the gaskets may slip. After you start tightening the bolts, tighten them with the ratchet. If applicable, use a torque wrench to tighten them to the manufacturer’s specifications.
Reassemble the parts in reverse order of removal. Replace any radiator hoses that are obviously rotted or cracked. When in doubt about tightening pressures, check your repair manual for torque specifications. Change the coolant with fresh antifreeze, warming the engine until the thermostat opens, and recheck the antifreeze level to fill it to level. Do a test drive and check the temperature gauge.
Warnings
Do not force the water pump bolts if they do not come out easily. Use liberal amounts to penetrate stuck bolts, letting them soak for several minutes before removing them. Water pump bolts tend to rust and break.