Thermostat - Jeep 1997 Grand Cherokee Service Manual

ZG
REMOVAL AND INSTALLATION (Continued)
occur when ambient (outside air temperature) is very
high.
• Engine loads and temperatures are high such as
when towing a trailer.
• Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.
LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.

THERMOSTAT

REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN-PLUG, THE COOLANT TANK CAP,
THE RADIATOR FILL VENT VALVE, OR LOOSEN
THE RADIATOR DRAINCOCK WITH THE SYSTEM
HOT AND PRESSURIZED. 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
Draining Cooling System for procedures.
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 (Fig. 14).
GLASSES WHEN SERVICING CONSTANT TENSION
CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps (Fig. 15). If
replacement is necessary, use only an original
equipment clamp with matching number or letter.
(2) Remove the upper radiator hose at the thermo-
stat housing.
(3) Remove the four thermostat housing bolts (Fig.
19)
(4) Remove the thermostat housing from the water
manifold.
(5) Remove the thermostat and rubber seal from
the water manifold.
(6) Thoroughly clean the rubber seal mating sur-
faces.
ALWAYS WEAR SAFETY
Fig. 19 Thermostat Removal/Installation
INSTALLATION
(1) Install a new rubber seal around the outer lip
of the thermostat (a notch is provided in the rubber
seal). Do not apply any adhesive to this seal.
(2) Install the replacement thermostat and rubber
seal as one assembly into the water manifold adapter
(the pointed end of the thermostat should be facing
towards the front of engine (Fig. 19). Observe the
recess groove in the water manifold adapter. Be sure
the thermostat vent is in the 12 o'clock position (Fig.
19).
(3) Position the thermostat housing and four bolts
to the water manifold.
CAUTION: Tightening the thermostat housing
unevenly or with the thermostat out of its recess
groove, may result in a cracked housing.
(4) Tighten the four housing bolts to 11 N·m (98
in. lbs.) torque.
(5) Install radiator hose to thermostat housing.
(6) Be sure that the radiator drain is tightly
closed. Fill the cooling system to the correct level
with the required coolant mixture. Refer to Refilling
Cooling System in this group for procedures.
(7) Start and warm the engine. Check thermostat
and hose for leaks.
COOLING SYSTEM 7 - 21