Cooling System Cleaning/Reverse Flushing; Drive Belt Tension - Jeep 1997 Grand Cherokee Service Manual

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CLEANING AND INSPECTION (Continued)
motion of opposite blades should not exceed 2.0 mm
(.090 inch). Test all blades in this manner.
WARNING: DO NOT ATTEMPT TO BEND OR
STRAIGHTEN FAN BLADES IF NOT WITHIN SPECI-
FICATIONS.
(4) Inspect fan assembly for cracks, bends, loose
rivets or broken welds. Replace fan if any damage is
found.
CAUTION: If fan blade assembly is replaced
because of mechanical damage, the fan pulley bear-
ing and viscous fan drive should also be inspected.
These components could have been damaged due
to excessive vibration.
CAUTION: Some engines equipped with serpentine
drive belts have reverse rotating fans and viscous
fan drives. They are marked with the word
REVERSE to designate their usage. Installation of
the wrong fan or viscous fan drive can result in
engine overheating.

COOLING SYSTEM CLEANING/REVERSE FLUSHING

CAUTION: The cooling system normally operates
at 90-to-117 kPa (13- to-17 psi) pressure. Exceeding
this pressure may damage the radiator or hoses.
CLEANING
Drain cooling system and refill with water. Run
engine with coolant tank pressure/vent cap installed
until upper radiator hose is hot. Stop engine and
drain water from system. If water is dirty, fill system
with water, run engine and drain system. Repeat
until water drains clean.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forc-
ing of water through the cooling system. This is done
using air pressure in the opposite direction of normal
coolant flow. It is usually only necessary with very
dirty systems with evidence of partial plugging.
REVERSE FLUSHING RADIATOR
Disconnect the radiator hoses from the radiator fit-
tings. Attach a section of radiator hose to the radia-
tor bottom outlet fitting and insert the flushing gun.
Connect a water supply hose and air supply hose to
the flushing gun.
CAUTION: The cooling system normally operates
at 90-to-117 kPa (13- to-17 psi) pressure. Exceeding
this pressure may damage the radiator or hoses.
Allow the coolant tank and radiator to fill with
water. When radiator is filled, apply air in short
blasts allowing radiator to refill between blasts. Con-
tinue this reverse flushing until clean water flows
out through rear of radiator cooling tube passages.
For more information, refer to operating instructions
supplied with flushing equipment. Have radiator
cleaned more extensively by a radiator repair shop.
REVERSE FLUSHING ENGINE
Drain the cooling system. Remove the thermostat
housing and thermostat. Install the thermostat hous-
ing. Disconnect the radiator upper hose from the
radiator and attach the flushing gun to the hose. Dis-
connect the radiator lower hose from the water
pump. Attach a lead away hose to the water pump
inlet fitting.
CAUTION: Be sure that the heater water control
valve is closed (heat off). This is done to prevent
coolant flow with scale and other deposits from
entering the heater core.
Connect the water supply hose and air supply hose
to the flushing gun. Allow the engine to fill with
water. When the engine is filled, apply air in short
blasts, allowing the system to fill between air blasts.
Continue until clean water flows through the lead
away hose. For more information, refer to operating
instructions supplied with flushing equipment.
Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo-
stat housing and install thermostat. Install the ther-
mostat housing with a new replacement rubber seal.
Refer to Thermostat Installation. Connect the radia-
tor hoses. Refill the cooling system with the correct
antifreeze/water mixture.
CHEMICAL CLEANING
In some instances, use a radiator cleaner (Mopar
Radiator Kleen or equivalent) before flushing. This
will soften scale and other deposits and aid the flush-
ing operation.
CAUTION: Be sure instructions on the container
are followed.
ADJUSTMENTS

DRIVE BELT TENSION

Initial belt adjustment is done with a adjustable
tensioner pulley. After the initial adjustment is per-
formed, an automatic belt tensioner is used to main-
tain correct belt tension at all times. For other
tensioner information and removal/installation proce-
dures, refer to Automatic Belt Tensioner in this
COOLING SYSTEM 7 - 25