Cooling System Hoses - Jeep 1997 Grand Cherokee Service Manual

(SHOWN IN SEALING POSITION) VACUUM VENT VALVE CROSS-SECTIONAL VIEW
7 - 6 COOLING SYSTEM
DESCRIPTION AND OPERATION (Continued)
Fig. 7 Radiator Pressure Cap—Typical
This causes the vacuum valve to open and coolant in
reserve/overflow tank to be drawn through connect-
ing hose into radiator. If the vacuum valve is stuck
shut, radiator hoses will collapse on cool-down.
A rubber gasket seals the radiator filler neck. This
is done to maintain vacuum during coolant cool-down
and to prevent leakage when system is under pres-
sure.
WATER PUMP
A centrifugal water
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
single serpentine drive belt on all engines.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary.
CAUTION: All 4.0L 6-cylinder engines are equipped
with a reverse (counterclockwise) rotating water
pump and thermal viscous fan drive assembly.
REVERSE is stamped or imprinted on the cover of
the viscous fan drive and inner side of the fan. The
TOP VIEW PRESSURE RATING PRESSURE VALVE FILLER NECK SEAL
pump circulates coolant
ROTATION DIRECTION AS FRONT VIEW VIEWED R STAMPED INTO IMPELLER
letter R is stamped into the back of the water pump
impeller (Fig. 8). Engines from previous model
years, depending upon application, may have been
equipped with a forward (clockwise) rotating water
pump. Installation of the wrong water pump or vis-
cous fan drive will cause engine over heating.
Fig. 8 Reverse Rotating Water Pump—4.0L6-
A quick test to determine if the pump is working is
to check if the heater warms properly. A defective
water pump will not be able to circulate heated cool-
ant through the long heater hose to the heater core.
5.2/5.9L ENGINES: One of the heater hoses is
connected to the water pump with a metal coolant
return tube (Fig. 9). A rubber o-ring forms a seal at
the water pump end of the tube.

COOLING SYSTEM HOSES

Rubber hoses route coolant to and from the radia-
tor, intake manifold and heater core.
The lower radiator hose is spring-reinforced to pre-
vent collapse from water pump suction at moderate
and high engine speeds.
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. 10). SNAP-ON CLAMP TOOL (NUMBER
HPC-20) MAY BE USED FOR LARGER CLAMPS.
ALWAYS WEAR SAFETY GLASSES WHEN SERVIC-
ING CONSTANT TENSION CLAMPS.
ROTATION DIRECTION AS
Cylinder
BACK VIEW VIEWED
ZG