Remove the Damaged Water Pump
Disconnect the Pontiac Bonneville's negative battery cable. Using a screwdriver, loosen the screw that connects the negative battery cable to the battery post. Pull the cable away from the post.
Discharge the Bonneville's cooling system by opening the cap on top of the radiator and unplugging the drain plug underneath the radiator. Position a large container under the drain hole to catch the draining coolant.
Raise the car off the ground using an automotive jack. Use an engine lift or support to hold the engine, if your Bonneville has a supercharged engine.
Remove the components that lead to the water pump. Lay them out in the order removed. In order, these parts include the air conditioning compressor splash shield, accessory drive belts, coolant hoses from the water pump and the pump pulley and its bolts.
Undo the bolts that secure the water pump to the block. Take off or scrape away the gasket. Remove and discard the gasket from the water pump.
Install the New Pump
Inspect the new pump to ensure that it's the correct pump and is free of defects. Place a new gasket the mount, where the water pump meets the engine. Use sealant as a bonding agent.
Place the gasket on the water pump and the pump onto the engine, where it meets the engine mount. There's no need for sealant here. Put the new bolts into the water pump. Torque the bolts to 115 inch pounds of torque.
Re-assemble the other components in the order removed. Re-insert the plug into the radiator. Move the jack stands and engine support and then lower the Pontiac Bonneville to the ground. Remove the jack.
Pour coolant back into the radiator. Replace the cap. Place the clamp back onto the battery post and tighten it with the screwdriver. Close the hood and test the car.
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To Replace the Water Pump in a Pontiac Bonneville
3.8L VIN 1 Bonneville Engine
Place a drain pan underneath the radiator. When the engine is cool, drain the cooling system from the radiator into the pan.
Support your vehicle with a jack under the car or with another engine support fixture.
Disconnect the negative battery cable and remove the air-conditioning compressor splash shield along with the supercharger with the accessory drive belts.
Remove the coil pack, if applicable, the front engine mount with the bracket, the supercharger belt tensioner, the power-steering pump and the idler pulley.
Loosen and remove the bolts attached to the water pump and the water pump pulley. Remove these two items from the engine.
Install the new water pump, placing a bit of bead sealer around the outside edge of the pump. Also attach a new gasket to the water pump.
Tighten the long water pump bolts to 22 foot pounds (30 Nm), and the short water pump bolts to 11 foot pounds (15 Nm).
Attach the water pump pulley, tightening the bolts to 115 inch pounds (13 Nm).
Reattach the engine mount bracket, tightening the nut that is positioned the closest to the air-conditioning compressor to 33 foot pounds (45 Nm) and all others to 58 foot pounds (78 Nm).
Reinstall the idler pulley, tightening the bolts to 37 foot pounds, the power-steering pump, tightening the bolts to 20 foot pounds (27 Nm), the front engine mount, tightening the bolts to 58 foot pounds (78 Nm), the Supercharger belt tensioner, tightening the bolts to 37 foot pounds (50 Nm) and the ignition coil pack assembly, tightening the nuts to 72 inch pounds (8 Nm).
Reattach all other components in the order they were removed and reattach the negative battery cable. Refill the cooling system and check for leaks.
3.8L VIN K Bonneville Engine
Place a drain pan underneath the radiator. When the engine is cool, drain the cooling system from the radiator into the pan and disconnect the negative battery cable.
Remove the accessory drive belt and disconnect the coolant hoses from the water pump.
Loosen and remove the water pump pulley bolts and remove the pulley. Align the bolt head of the long bolt up with the hole in the frame rail to remove it.
Remove the water pump bolts and the water pump.
Squeeze some sealer around the outer edge of the water pump and install the pump with a new gasket into the engine, tightening the long bolts to 22 foot pounds (30 Nm) and the short bolts to 11 foot pounds (15 Nm).
Reinstall the water pump pulley, tightening the bolts to 115 inch pounds(13 Nm) and reattach all other components in the reverse order in which they were removed.
Refill the cooling system and reattach the negative battery cables. Start the engine and check for leaks when the engine reaches normal operating temperatures.
