Chrysler Vehicle User Manual page 298

TJ
ENGINE COOLANT
THERMOSTAT
DESCRIPTION
CAUTION: Do not operate an engine without a ther-
mostat, except for servicing or testing.
The thermostat (Fig. 8) on all gas powered engines
is located beneath the thermostat housing at the
front of the intake manifold.
The thermostat is a wax pellet driven, reverse pop-
pet choke type.
Coolant leakage into the pellet container will cause
the thermostat to fail in the open position. Thermo-
stats very rarely stick. Do not attempt to free a ther-
mostat 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
increased exhaust emissions and crankcase condensa-
tion that can result in sludge formation.
Fig. 8 Thermostat—Typical
1 - LONG BOLT
2 - GASKET
3 - THERMOSTAT
4 - THERMOSTAT HOUSING
5 - SHORT BOLT
warmup performance,
OPERATION
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.
REMOVAL
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Drain the coolant from the radiator until the
level is below the thermostat housing (Refer to 7 -
COOLING - STANDARD PROCEDURE).
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER
6094) (Fig. 31). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 32). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
(2) Remove radiator upper hose and heater hose at
thermostat housing.
(3) Disconnect wiring connector at engine coolant
temperature sensor.
(4) Remove thermostat housing mounting bolts,
thermostat housing, gasket and thermostat (Fig. 9).
Discard old gasket.
(5) Clean the gasket mating surfaces.
REMOVAL
(1) Drain cooling system below thermostat housing
level.
(2) Disconnect engine coolant temperature sensor.
(3) Disconnect heater supply hose.
(4) Remove housing attaching bolts (Fig. 10).
(5) Remove housing, gasket and thermostat (Fig.
10).
ENGINE 7 - 29