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Follow the upper radiator hose to the point where the hose connects to the LeSabres engine. The metal connector to which the hose connects is the thermostat housing.

Disconnect the radiator hose from the housing by squeezing the pressure tabs on the radiator hose clamp together with a pair of pliers. With the pressure released, pull the hose off the housing. A small amount of fluid may run onto the engine block. To minimize this, hold the hose vertical for a few seconds to drain the fluid back into the radiator.

Remove the two bolts that secure the thermostat housing to the Buicks intake manifold with a 7/16-inch socket and ratchet. With the bolts removed, apply pressure on the side of the housing with the ball of your hand to break the seal between the housing and the intake.

Pull the old thermostat out of the intake manifold and plug the hole with a shop towel to prevent anything from getting into the coolant system of your Buick.

Scrape all the old gasket material off the bottom of the thermostat housing and the mating surface of the intake manifold. Brush off any debris with a shop towel.

Remove the shop towel from the intake manifold and place the new thermostat into the hole. The end with the large spring submerges into the intake manifold and the end with the pin sits inside the thermostat housing.

Place a thin bead of RTV gasket maker on the bottom edge of the thermostat gasket. Allow the RTV gasket maker to firm up for approximately 20 minutes. This creates a small layer of "skin" on the RTV.

Place the thermostat housing onto the intake manifold and bolt it into place. Do not wipe off any excess RTV. It serves as additional sealant.

Squeeze the pressure tabs on the radiator hose clamp. With pressure released, slide the hose onto the thermostat housing and then let go of the tabs.

Disconnect the negative terminal on the battery with a socket wrench to avoid starting the engine accidentally. Open the fuel filler cap to relieve the vapor pressure in the fuel tank. Remove the cap for the fuel pressure fitting on the fuel rail, and wrap a shop towel around the fuel pressure fitting. Attach fuel pressure valve J 34730-1A to the fuel pressure fitting, and place the bleed hose into container approved for gasoline. Open the valve to release the pressure in the fuel system, and fasten the fuel filler cap.

Raise the vehicle with a jack and support it on jack stands. Disconnect the filler vent hose from the fuel tank and connect the open end of the hose to a hand-operated pump. Drain as much fuel from the fuel tank is possible into a gasoline container.

Detach the electrical connector for the fuel sender and remove the fuel lines from the fuel sender. Disconnect the quick connectors for the fuel pipe and support the fuel tank with jack stands. Remove the bolts for the fuel tank retaining straps with a socket wrench and disconnect the rear hangar of the exhaust system. Disconnect the fuel tank and remove it from the vehicle.

Turn the locking ring for the fuel sender assembly counterclockwise with tool J-24187. Lift the fuel sender assembly carefully from the fuel tank, detach the fuel pump from the fuel gauge sender unit. Discard the O-ring on top of the fuel sender. Disconnect the electrical connector for the fuel comp, and release the clamps around the fuel pump. Pull the fuel from its rubber connectors.

Install the new fuel pump by performing Steps 2 through 4 in reverse, ensuring that you also install a new O-ring. Fill the fuel tank, and connect the negative terminal on the battery with a socket wrench. Turn the ignition on to pressurize the fuel system, and check for fuel leaks.