Cherokee 4WD L6-4.0L VIN S (1998)
Water Pump: Description and Operation
A centrifugal water pump circulates coolant 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 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 a small hole to allow
seepage to escape. The water pump seals are lubricated by the antifreeze in the coolant mixture. No additional lubrication is necessary.
Fig.5 Reverse Rotating Water Pump- Typical
CAUTION: All engines are equipped with a reverse (counter-clockwise) rotating water pump and viscous fan drive assembly. REVERSE is stamped or
imprinted on the cover of the viscous fan drive and inner side of the fan. The letter R is stamped into the back of the water pump impeller.
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 will cause engine overheating.
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 coolant through the long heater hose to the heater core.
