Chrysler Full-Size Vans 1967-1988 Repair Guide

Thermostat

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REMOVAL & INSTALLATION



See Figures 1 through 8

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Fig. Fig. 1: Thermostat mounting details for the V6 engine-similar to the V8 engines



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Fig. Fig. 2: To remove the thermostat on L6 engines, loosen the upper radiator hose clamp ...



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Fig. Fig. 3: ... and remove the upper radiator hose



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Fig. Fig. 4: Loosen and remove the thermostat housing retaining bolts



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Fig. Fig. 5: Pull the housing off of the engine ...



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Fig. Fig. 6: ... then, noting its position, remove the thermostat from the engine



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Fig. Fig. 7: For thermostat removal on V8 engines, unbolt the water outlet housing ...



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Fig. Fig. 8: ... then, lift the housing and remove the thermostat

  1. Drain the cooling system to below the level of the thermostat.
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CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the upper radiator hose from the thermostat housing. Note the positioning of the thermostat. It is important that the thermostat is correctly installed.
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  3. Withdraw the housing bolts and remove the housing and the thermostat.
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  5. 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.
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  7. 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.
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  9. 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.
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  11. 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.
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  13. 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..
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  15. Connect the upper radiator hose.
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  17. 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.
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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.

 
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