How to Change a Thermostat in a Ford Bronco

A Bronco’s thermostat operates to prevent the flow of antifreeze from the radiator to the engine to allow the engine to quickly warm up. Once the engine has reached its normal operating temperature, the thermostat opens, thereby allowing the antifreeze from the engine to circulate though the engine. Over time, a thermostat can stick in one position. If the thermostat is stuck in the open position, it will take the engine longer to reach normal operating temperature. If the thermostat is stuck in the closed position, the fluid within the radiator will be prevented from entering the engine, and will result in an engine which quickly overheats, particularly if the Bronco is used over off-road terrain. Thankfully, replacing a Bronco’s thermostat is a straightforward task.

Remove the radiator cap located on the top of the radiator by turning the cap in a counterclockwise direction.

Turn the draincock located on the bottom of the radiator to drain the fluid from the radiator. The draincock faces the engine and is located on the driver’s side of the radiator. Use a wrench to remove the draincock by turning it in a counterclockwise direction.

Remove the upper radiator hose from the radiator and the thermostat housing. The radiator hose is held into place with two hose clamps, one on each end of the radiator hose. To release the clamps, turn the screw located on the clamp in a counterclockwise direction with a flathead screwdriver. Pull the upper radiator hose away from the radiator and the thermostat housing.

Remove the water pump hose from the thermostat housing. The water pump hose is attached to the thermostat housing with a single hose clamp. Release the clamp in the same manner described in step 3, then pull the hose away from the thermostat housing.

Remove the thermostat housing from the intake manifold to reveal the thermostat. The thermostat housing is attached to the intake manifold with two bolts. Remove the bolts by turning them in a counterclockwise direction with a wrench, then pull the thermostat housing away from the intake manifold to remove it.

Remove the thermostat from the intake manifold. The thermostat can simply be pulled out of the intake manifold.

Insert the new thermostat into the intake manifold. Note that one side of the thermostat has a large spring. This spring must face away from the intake manifold when installed.

Reinstall the thermostat housing. Coat both sides of a new thermostat housing gasket with gasket sealer. Rest the gasket onto the mating surface of the thermostat housing.

Ensure that the gasket’s holes align with the holes on the thermostat housing. Place the thermostat housing over the thermostat then insert the two thermostat housing bolts through the housing and into the intake manifold. Secure the housing to the intake manifold by turning these two bolts in a clockwise direction with a wrench to tighten them.

Attach the water pump hose to the thermostat housing by first sliding the hose over its port on the housing. Slide the hose clamp to the end of the hose, then tighten the clamp by turning the clamp’s screw in a clockwise direction with a flathead screwdriver.

Attach the radiator hose to the thermostat housing and to the radiator. Secure both ends of the radiator hose in the same manner described in step 9.

Insert the radiator’s draincock into the radiator and turn the draincock in a clockwise direction with a wrench to secure it to the radiator.

Fill the radiator with new antifreeze, then attach the radiator cap to the radiator by turning the cap in a clockwise direction.

Allow at least two hours to pass before starting the engine to permit the gasket sealer to set.