The thermostat used in these engines is a conventional wax pellet type designed to keep the engine operating at 195°F (90°C). The thermostat opens at approximately 215°F (102°C). so it does do not restrict the flow to the radiator as the coolant temperature rises to around 220°F (104°C). in hot weather. Above 215°F (102°C), the coolant temperature is controlled by the radiator, fan and outside air temperature, not the thermostat.
When the engine is cold, the thermostat is closed and the cooling system has no flow through the radiator. The coolant flows through the engine, heater core, coolant bottle and by-pass. When the engine is warm, the thermostat is open and coolant flows through the radiator, heater core, coolant bottle and bypass.
The engine thermostat is located in the so-called water box formed in the front of the lower intake manifold. This thermostat has an air bleed located in the thermostat housing. Service this vehicle with ethylene glycol base coolant with a silicate inhibitor such as MOPAR® anti-freeze or equivalent in a 50/50 mix with distilled water. The use of aluminum cylinder heads, intake manifolds and water pumps requires special corrosion protection. Chrysler Corp. does not recommend the use of Propylene Glycol as they provide less freeze protection and less corrosion protection.
REMOVAL & INSTALLATION
See Figures 1, 2, 3, 4, 5 and 6
- Disconnect negative battery cable.
- Allow cooling system to cool completely. Place a pan under the radiator drain, located at the lower right side of the radiator. Open the valve to drain the cooling system to a level just below the thermostat. Do NOT drain the cooling system completely, unless the coolant is being changed. Close the valve.
- Loosen the radiator hose clamp from the upper radiator hose at the thermostat housing and if necessary disconnect the hose from the housing.
- Remove the thermostat bolts and housing.
- Remove the thermostat and discard the gasket. Thoroughly clean both gasket sealing surfaces.
- Clean the thermostat housing bolts well. On any engine, bolts that thread into the water jacket are subject to rust and corrosion. A bolt with rust or debris in the threads can easily strip out the threads in an aluminum manifold requiring a time-consuming thread repair operation. Clean the bolts well and lightly lubricate before installation.
- Install the thermostat into the recess in the intake manifold. Place a new gasket, moistened with water, on the water inlet mating surface on the intake manifold.
- Install the thermostat housing over the gasket and thermostat and tighten the mounting bolts to 21 ft. lbs. (28 Nm) on the 3.3L engine and 105 inch lbs. (12 Nm) on the 3.5L engine.
- Connect the upper radiator hose to the thermostat housing and tighten the radiator hose clamp.
- Refill and bleed the cooling system.