How to Install a Powerstroke Engine Thermostat

Open the hood of your truck and allow the engine to cool thoroughly so that you will not be scalded by hot radiator coolant. Skip this step if your truck has not been running in the last few hours.

Remove the filler cap from the radiator tank at the top of the engine and place it aside. Place a clean drain pan that has a five-gallon capacity under the drain plug on the driver’s side of the radiator, just behind the front bumper. Loosen, but do not remove, the radiator drain plug with a 19mm wrench. Allow the coolant to drain fully into the drain pan. Tighten the drain plug and carefully slide the drain pan out from under the vehicle.

Trace the upper radiator hose from the upper driver‘s side of the radiator to the metal thermostat housing. Spray penetrating fluid on the three bolts that hold the housing to the engine and allow it to soak in for a few minutes. Squeeze the tabs of the hose clamp on the thermostat housing with a pair of pliers and slide to clamp away from the housing. Use a twisting and pulling motion on the radiator hose to remove it from the housing.

Remove the three thermostat retaining bolts with a 8mm wrench in a counterclockwise direction. Place the bolts aside. Carefully pry the housing from the engine with a flat blade screwdriver. Lift the present thermostat from the housing and discard it. Place a new thermostat into the housing, using the same orientation as the old thermostat.

Pull the old “O” ring gasket from the bottom of the thermostat housing and discard it. Clean the mating surface of the housing and the engine with a gasket scraper. Place a new “O” ring gasket into the grooves on the underside of the housing. Position the housing back over the thermostat and tighten the retaining bolts.

Push the upper radiator hose back over the thermostat housing until it is fully seated. Squeeze the tabs on the hose clamp with pliers and slide the clamp back into its original position on the hose.

Place a funnel into the radiator tank opening and carefully pour the coolant from the drain pan back into the radiator. Replace the cap and close the hood.