How to Change a Water Pump on a 98 Chevy Blazerby Don BowmanUpdated November 07, 2017
Items you will need
Set of wrenches
3/8-inch drive sockets
3/8-inch drive ratchet
RTV silicone sealant
1 gallon antifreeze
Pair of pliers
The longevity of the 1998 Chevy Blazer's water pump depends on the tightness of the serpentine belt and the amount of antifreeze in the system. A belt that is too tight can cause accelerated wear on the pump's bearing. The antifreeze acts as a lubricant, and a lack of it will cause excessive wear. Diagnosing a water pump is quite simple. If it makes a terrible rattling noise and the pulley is wobbly, it needs to be replaced. If an inordinate amount of antifreeze is draining from the water pump, it needs to be replaced. Water pumps generally go bad suddenly, with little or no warning.
Place the drain pan under the radiator and open the petcock. Allow the antifreeze to drain. Close the petcock. Remove the upper radiator hose, using the screwdriver. Locate the bolts securing the fan shroud to the radiator. Remove these bolts, using a 10mm socket and ratchet.
Loosen all four bolts securing the engine fan to the water pump, using a 13mm wrench. Just loosen the bolts--do not remove them. Relieve the tension on the serpentine belt, using a wrench to move the tensioner away from the belt. Remove the belt from the alternator and the water pump pulley.
Remove the four bolts from the engine fan to water pump pulley. Lift the fan and fan shroud as a pair straight up and out of the vehicle. Remove the water pump pulley by pulling it off.
Remove all the hoses attached to the water pump by removing the clamps and pulling them off. They may have one of two different types of clamps. One is the type that could be loosened with a screwdriver and the other is a spring type. The spring type needs to be squeezed with pliers to loosen it.
Remove the four bolts securing the water pump to the block. There are two 4-inch bolts on each side of the water pump. Remove these with a 15mm socket and ratchet. Pull the pump off.
Clean all the gasket material off the two openings in the block where the water pump seals using the gasket scraper. Clean these areas well and wipe off with a cloth so they do not leak later. Smear a smooth coat of RTV on both sides of the new gaskets. Place the gaskets on the water pump and allow the RTV to set for five minutes.
Place the water pump bolts in the holes in the water pump. Hold the top two bolts and carefully move the pump toward the block, constantly watching the alignment of the two top bolts with the holes in the block. Start to thread the two top bolts in their holes in the block. Look at the gasket and if it is in place, push the pump toward the block and thread the bottom bolts into the block. Now tighten all four bolts using, the 15mm socket and ratchet.
Attach the hoses and tighten the clamps. Install the rest of the parts in reverse order of removal and fill the radiator with a 50-50 mix of antifreeze and water.
Dispose of the antifreeze in a responsible manor with the knowledge that this is harmful or fatal to animals and harmful to our ecology.
Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).