OPERATION
The engine cooling thermostat is a wax pellet
driven, reverse poppet type. The thermostat is
located in the inlet side of the engine to provide fast
warm up and to optimize a consistent temperature in
the engine. The thermostat is designed to prevent
leakage through it and to guarantee a minimum
engine operating temperature of 82°C (180°F). They
also automatically reach wide open at a temperature
of approximately 95°C (203°F) so they do not restrict
flow to the radiator as temperature of the coolant
rises in hot weather to around 104°C (220°F). Above
102°C (215°F) the coolant temperature is controlled
by the radiator, fan, and ambient temperature, not
the thermostat.
WATER PUMP
DESCRIPTION
The 2.7L pump has a die cast aluminum housing
and a plastic swept vane impeller. It bolts directly to
the cylinder block, behind the timing chain cover
(Fig. 4). The water pump is driven by the back side
of the engine primary timing chain.
The 3.2/3.5L water pump has a die cast aluminum
housing and a plastic swept vane impeller. The hous-
ing bolts directly to the right rear timing belt cover,
using a O-ring gasket for pump to cover sealing (Fig.
5). The pump is driven by the engine timing belt.
OPERATION
The water pump is the heart of the cooling system,
pumping the coolant through the engine block, cylin-
der head, heater core, and radiator.
RADIATOR
DESCRIPTION
The radiators are cross-flow types (horizontal
tubes) with design features that provide greater
strength as well as sufficient heat transfer capabili-
ties to keep the engine satisfactorily cooled. The radi-
ator cooling tubes are made of aluminum and the
side tanks are plastic (Fig. 6). The radiator is posi-
tioned in the front part of the engine compartment to
Fig. 2 Thermostat and Housing—2.7L Engine
1 – THERMOSTAT AND GASKET
2 – THERMOSTAT HOUSING/COOLANT INLET
Fig. 3 Thermostat and Housing—3.2/3.5L Engines
1 – THERMOSTAT HOUSING/COOLANT INLET
2 – THERMOSTAT
3 – GASKET
Fig. 4 Water Pump—2.7L Engine
1 – WATER PUMP BODY
2 – IMPELLER
3 – GASKET
7 - 4 COOLING SYSTEM LH
DESCRIPTION AND OPERATION (Continued)
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