How to Change the Thermostat on a 1994 Mustang 5.0
- 1). Raise the hood and position the catch pan on the ground, directly below the upper radiator hose.
- 2). Loosen the hose clamp on the engine side of the upper radiator hose and pull the hose off the thermostat housing. Aim the hose end down towards the catch pan so any escaping antifreeze lands in the pan.
- 3). Unbolt the thermostat housing using the socket set. Lift the housing up and off the intake manifold. Note the position and alignment of the old thermostat. Pull the old thermostat out by hand.
- 4). Inspect the thermostat housing and replace it if you note any signs of pitting or corrosion on the interior or sealing surfaces.
- 5). Put the replacement thermostats o-ring around the thermostats flange, if it isn't already there. Most thermostats come with the o-ring in the packaging, but not necessarily on the thermostat.
- 6). Put the replacement thermostat into the thermostat well, making sure to orient and align it in the same manner as the old thermostat. If you put the replacement thermostat in upside down, it will not function.
- 7). Reinstall the thermostat housing, or replacement housing depending on your determination in step 4. Thread the bolts back in by hand and tighten them down with the socket set.
- 8). Slide the upper radiator hose back over the thermostat housing inlet and tighten the hose clamp down with the socket set.
- 9). Top the radiator as needed based on the amount of antifreeze (if any) you lost during step 2. Always use a 50/50 mixture of antifreeze and distilled water. If you did not lose any coolant in step 2, disregard this step.