How do you replace the water pump on a 1988 Cadillac DeVille fwd 4.5L V8?

Answer 1

You will have to remove the serpentine belt and hold the water pump pulley still while loosening the pulley bolts. There are 10 or more 10mm bolts holding the water pump on. Once you have removed the pump you can remove the pulley also. It is a very strange looking pump. When you are reinstalling the new pump use 'red' RTV to make sure you get the best seal as it is the high temperature RTV. After applying a 1/8inch bead around each bolt hole simply connect the dots with another 1/8inch bead around the edge of the pump. I highly recommend allowing the RTV to cure for around 20 to 30 minutes before reinstalling the new pump. Make sure that you do not over tighten the 10mm bolts. If one breaks off you will have to pull the engine to get the broken portion out of the engine block. Simply snug down the bolts until you see the RTV start squish out around the pump slightly. With RTV you do not have to tighten nearly as tight as with a gasket. Also make sure that all the old RTV or gasket is thouroughly removed before reinstallation. After you fill the cooling system and before you start the engine check for any leaks. If you see some seeping simply tighten the bolts a little more. If the seep stops then start the engine and check for leaks while the engine is idling and still cold. You may have to tighten a bit more if you still have seeping. If not allow the enging to run until it reaches normal operating temperature. Allow it to run for a short while after it is warmed up. I personally recommend that you replace the thermostat at the same time. Most of the GM engines in this size range throung the 80s are either aluminum or have aluminum heads which are prone to get warped if the engine overheats. This is true of all vehicles with aluminum heads. Domestic or foreign.