Hang the thermostat on a hook in order to perform an operational check of the thermostat. Hang the thermostat in a 33 percent glycol solution at -12°C (10°F) below the temperature indicated on the valve. The valve will close when you submerge the valve and agitate the coolant.
Use the following procedure to check for engine overheating, boiling or poor engine cooling:
- Relieve the pressure and carefully remove the radiator cap.
- Rub a 96.6°C (206°F) temperature stick on the thermostat housing.
- Warm up the engine at a fast idle. Watch for coolant flow before the mark begins to melt.
| • | If the coolant does not flow, install a new thermostat. Recheck the system in order to ensure the system is operating properly. |
| • | If there is coolant flow, the problem is caused by something other than a faulty thermostat. |
Use the following procedure in order to check for a cold engine, slow warm-up or not enough heat:
- Relieve the pressure and carefully remove the radiator cap.
- Rub a 86.6°C (188°F) temperature stick on the thermostat housing.
- Warm up the engine at a fast idle. Watch for coolant flow before the mark begins to melt.
| • | If there is coolant flow, install a new thermostat. Recheck the system in order to ensure the system is operating properly. |
| • | If there is no coolant flow, the problem is caused by something other than a faulty thermostat. |
A temperature stick is a pencil like device that has a wax material containing certain chemicals. These chemicals melt at a certain temperature. Use a temperature stick in order to determine a thermostat's operating temperature by rubbing the 86.6°C (188°F) and the 96.6°C (206°F) sticks on the thermostat housing. The marks made by the sticks should melt when the coolant temperatures of 86.6°C (188°F) and 96.6°C (206°F) are reached. These temperatures are the normal operating range of the thermostat. If the coolant flows as indicated in the following procedures, the thermostat may be worn.
