How to replace a water pump on a 1998 Lumina?

Answer 1

First, obtain a replacement water pump based on your make and model from your local parts store - typically costs around $25, a new gasket, a small tube of silicone water pump sealant. NOTE use only water pump sealant for this purpose. Second, assemble the tools you will need to do the work. That consists of, as a minimum, a screwdriver, small wrenches (small 1/4" drive metric sockets are preferred), a 1x2 wood pry bar about 3 feet long, a torque wrench, a drop light & a rubber strap wrench. Raise the hood. Locate the water pump on the left front of the engine as you stand in front of the car. It is located where the upper radiator hose connects to the engine. Remove the small plastic "guard" that is attached to the top of the water pump with one bolt. This guard prevents fingers from accidentally being pulled into the belt that drives the water pump. The guard has the serpentine belt routing pattern on it. Set the guard and its bolt aside. Remove the end of the radiator hose that connects to the water pump and drain the upper engine coolant to a container placed immediately below the hose. This may be as much as a gallon of liquid. Take care to not allow the coolant to become fouled with engine dirt and debris. NOTE: this is a good time to replace the old radiator hose. Take the wood pry bar and set the lower end under the idler pulley that maintains tension on the serpentine accessory belt. Use the inner fender panel immediately in front of the coolant reservoir as a fulcrum. Lift the tension idler just enough so that slack is sufficient in the belt to remove the belt from the grooved pulley adjacent to the water pump (Note the smooth backside of the serpentine belt drives the water pump pulley). Leave the belt otherwise engaged with other pulleys while working on the water pump. When the belt has been removed from the water pump pulley you are ready to begin to disassemble the water pump. Remove four bolts from the smooth bell-shaped pulled that drives the water pump. Remove the bell-shaped pulley and set aside with the four bolts. Take a permanent marker and put a "witness" mark on both parts of the water pump housing for realignment during reassembly. Remove six bolts in an annular pattern around the perimeter of the water pump. Take care to not lose any of these bolts in the area of the chassis below as they will be almost impossible to locate if you do. When all bolts have been removed, tap the outer edge of the water pump housing lightly with a wrench or small hammer to loosen the sealant at the gasket. Set the six bolts aside for reassembly. The water pump should loosen easily and drop into your hand. Inspect the surface of the remaining water pump housing for any remaining gasket material. If there is any remaining gasket material NOTE: DO NOT SCRAPE WITH A STEEL TOOL! The water pump housing is aluminum and if it is gouged with a steel tool, it will leak. Carefully remove the excess gasket material with a plastic or wood tool. Remove any sealant remaining on the mating surface. Once the gasket area is clean, take the new gasket and find the correct orientation to the bolt holes on the water pump. The holes are not exactly equally spaced and will sometimes require several tries to find the exact matching orientation. spread the water pump silicone sealant on the new water pump gasket surface evenly and set the new gasket in it with all holes aligned. Note the witness mark on the old pump housing for proper alignment. Spread silicone sealant evenly on the surface of the engine mounted part of the water pump and install the new pump in the proper orientation and install the six bolts finger tight in each of the bolt holes. Begin to tighten the six bolts in a criss cross pattern but do not torque to full tightness until they are all snug. Then tighten each of the bolts to the required torque value (between 18 and 22 inch pounds depending on model - consult the factory specifications). NOTE THAT TOO MUCH TORQUE WILL RESULT IN STRIPPING THE THREADS IN THE HOUSING! Too little will allow the pump to leak at the gasket and will cause wear in the pulley shaft. If the threads are stripped, that is a major problem that may be beyond your ability to repair. It may require replacement of the engine-mounted portion of the water pump housing. Once the six bolts are properly torqued, reinstall the bell shaped pulley with its four bolts. These bolts have to be torqued also, but are not as critical since they thread into a steel flange on the pulley shaft. This is where you may have to use the strap wrench to hold the bell-shaped pulley while you tighten the four bolts. Using the pry bar to lift the idler pulley, reinstall the serpentine belt in its proper pattern, making sure that the inside grooves are in their proper alignment with the crankshaft pulley and other pulleys on the engine and other accessories. Once the belt has been properly positioned, release the idler pulley to put the proper tension on the serpentine belt. Reinstall the radiator hose to the water pump housing. It is preferred to use a stainless steel screw clamp rather than the spring clamps that are original equipment because they are easier to remove and install. Reinstall the plastic keeper above the bell shaped pulley. Pour the drined coolant that was originally removed into the reservoir that is located on the left inner fender panel. You may wish to replace all of the coolant in the system. If so, wait until this work has been successfully completed, then drain the entire system and replace as per manufacturer's specifications. Remove the radiator cap to allow excess air to excape and to avoid an air "lock up" when the engine is started. Remove all tools and parts from the area. Leave the hood up. Start the engine and allow it to run for 5-10 minutes. Visually check the area under the water pump for evidence of leaks. If none are seen after 10 minutes, reinstall the radiator cap and take the car for a short drive. Check again for evidence of leaks. If any coolant is leaking around the water pump, you will have to tighten the water pump housing bolts, by first loosening them slightly and re-torqueing them. Once you are sure there are no leaks, put your tools away and pat yourself on the back. You have just saved yourself between $400 and $600 for a garage to do the same thing. If the serpentine belt became wet during this work, you may have to dry it off (without engine running) and apply some belt dressing - not too much - to it to prevent slippage. This job takes between 2 and 3 hours for a novice to do this work depending on your skill and patience. The next time you do it, you should be able to do it in about 1 hour. Good luck.