REMOVAL & INSTALLATION
See Figures 1 through 8
- Drain the cooling system to below the level of the thermostat.
- Remove the upper radiator hose from the thermostat housing. Note the positioning of the thermostat. It is important that the thermostat is correctly installed.
- Withdraw the housing bolts and remove the housing and the thermostat.
- Check to make sure that the thermostat valve closes tightly. If the valve does not close completely due to foreign material, carefully clean the sealing edge of the valve while being careful not to damage the sealing edge. If the valve does not close tightly after it has been cleaned, a new thermostat must be installed.
- Immerse the thermostat in a container of warm water so that its pellet is completely covered and does not touch the bottom or sides of the container.
- Heat the water and, while stirring the water continuously (to ensure uniform temperature), check the water temperature with a thermometer at the point when a 0.001" feeler gauge can be inserted in the valve opening at a water temperature with +- 5° of the standard thermostat temperature. If the thermostat does not open within the temperature range, replace it with a new thermostat.
- Continue heating the water to a temperature of approximately 20° higher than the standard thermostat opening temperature. At this point, the thermostat should be fully open. If it is not, install a new thermostat.
- To install, use a new gasket and position the thermostat so that its pellet end (the part with the spring) is toward the engine block. On the six, the vent hole must be up. Refit the thermostat housing and tighten its securing bolts to 25-30 ft. lbs..
- Connect the upper radiator hose.
- Fill the cooling system to 1.25" below the filler neck with the correct water and antifreeze mixture. Warm the engine and inspect the upper radiator hose and the thermostat housing for leaks.
Poor heater output and slow engine warm-ups is often caused by a thermostat stuck in the open position; occasionally one sticks shut causing immediate overheating. Do not attempt to correct an overheating condition by permanently removing the thermostat. Thermostat flow restriction is designed into the system; without it, localized overheating due to turbulence may occur.