RAM 2500 Truck 2WD V8-5.9L VIN 5 HDC (1998)
Thermostat-5.9L Diesel-Typical
The thermostat of the 5.9L diesel engine is located in the thermostat housing. The housing is located behind the generator mounting bracket, at front of
cylinder head.
Gas powered engines: The thermostat is a wax pellet driven, reverse poppet choke type (3.9L/5.2L/ 5.9L), or moveable sleeve type (8.0L V-10). The
wax pellet is located in a sealed container at the spring end of the thermostat. When heated, the pellet expands, overcoming closing spring tension and
water pump pressure to force the valve to open. Coolant leakage into the pellet container will cause the thermostat to fail in the open position.
Thermostats very rarely stick. Do not attempt to free a thermostat with a prying device.
The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing.
Operating without a thermostat causes longer engine warm-up time, unreliable warm-up performance, increased exhaust emissions and crankcase
condensation that can result in sludge formation.
CAUTION: Do not operate an engine without a thermostat, except for servicing or testing.
PURPOSE
The thermostat controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. The thermostat is closed
below 88°C (192°F). When the coolant reaches this temperature, the thermostat begins to open, allowing coolant flow to the radiator. This provides
quick engine warm-up and overall temperature control. The thermostat is designed to provide a minimum engine operating temperature of 88 to 93°C
(192 to 199°F). It should be fully open for maximum coolant flow during operation in hot ambient temperatures of approximately 104°C (220°F).
Above 104°C (220°F), coolant temperature is controlled by the radiator, fan and ambient temperature.
