Cooling System; Engine Accessory Drive Belts; Description And Operation - Dodge ram truck 3500 1996 Service Manual

B R
COOLING SYSTEM 7 - 5
G E N E R A L I N F O R M A T I O N ( C o n t i n u e d )
The thermostat of the 5.9L diesel engine is located
in the thermostat housing (Fig. 7)., The housing is
located behind the generator mounting bracket, at
front of cylinder head.
Fig. 7 Thermostat—5.9L
Diesel—Typical
Gas powered engines: The thermostat is a wax pel­
let 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. Cool­
ant 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 sum­
mer seasons. An engine should not be operated with­
out a thermostat, except for servicing or testing.
Operating without a thermostat causes longer engine
warmup time, unreliable warmup performance,
increased exhaust emissions and crankcase condensa­
tion that can result i n sludge formation.
CAUTION: Do not operate an engine without a
thermostat, except for servicing or testing.'
ENGINE ACCESSORY DRIVE BELTS
All vehicles are available with either a 3.9L V-6, a
5.2L V-8, two different 5.9L V-8 engines, an 8.0L V-10
or a 5.9L in-line 6 cylinder diesel engine.
The accessory drive components are operated by a
single, crankshaft driven, serpentine drive belt on all
engines. An automatic belt tensioner is also used to
maintain correct belt tension at all times. This is
used on all engines. Refer to Automatic Belt Ten­
sioner proceeding in this group.
BELT TENSION—ALL ENGINES
Correct accessory drive belt tension is required to
be sure of optimum performance of belt driven engine
accessories. I f specific tension is not maintained, belt
slippage may cause; engine overheating, lack of
power steering assist, loss of air conditioning capac­
ity, reduced generator output rate and greatly
reduced belt life.
It is not necessary to adjust belt tension on any
engine. A l l engines are equipped with an automatic
belt tensioner. The tensioner maintains correct belt
tension at all times. For other tensioner information
and removal/installation procedures, refer to Auto­
matic Belt Tensioner proceeding in this group. Due to
use of this belt tensioner, do not attempt to use a belt
tension gauge on any engine.
D E S C R I P T I O N A N D O P E R A T I O N
THERMOSTAT—V-6, V-8, AND V-10
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 temper­
ature, the thermostat begins to open, allowing cool­
ant flow to the radiator. This provides quick engine
warmup and overall temperature control. The ther­
mostat 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.
THERMOSTAT—DIESEL
The thermostat controls the operating temperature
of the engine by controlling the amount of coolant
flow to the radiator. When coolant temperature is
below 83°C (181°F), the thermostat is closed (Fig. 8).
When coolant temperature reaches 83°C (181°F),
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 83°C (181°F) and to be fully open for
maximum coolant flow at approximately 95°C
(203°F). Above 95°C (203°F), coolant temperature is
controlled by the radiator, fan and ambient tempera­
ture.
The air bleeds (jiggle pins) that were used on the
thermostats of diesel engines in previous years are
no longer used. They have been replaced by a verti­
cally mounted one-way check valve (jiggle pin) and a
rubber bypass hose. The check valve is used as a ser­
vicing feature and will vent air when the system is