OPERATION
OPERATION
A centrifugal water pump circulates coolant through
the water jackets, passages, intake manifold, radiator
core, cooling system hoses and heater core, this cool-
ant absorbs the heat generated when the engine is
running. The pump is driven by the engine crankshaft
via a drive belt.
WATER PUMP BYPASS – 3.7L/4.7L
ENGINE
When the thermostat is in the closed position the
bypass gallery is not obstructed allowing 100% flow.
When the thermostat is in the open position the pill
partially covers the bypass hole, reducing the amount
of bypass flow. This design allows the coolant to reach
operating temperature quickly when cold, while adding
extra cooling during normal temperature operation.
DIAGNOSIS AND TESTING - WATER PUMP
A quick test to determine if pump is working is to check if heater warms properly. A defective water pump will not be
able to circulate heated coolant through the long heater hose to the heater core.
REMOVAL
3.7L/4.7L ENGINE
The water pump on 3.7L/4.7L engines is bolted
directly to the engine timing chain case cover.
1. Disconnect the negative battery cable.
2. Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
3. Remove fan/viscous fan drive assembly from water
pump (Refer to 7 - COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - REMOVAL). Do not attempt
to remove fan/viscous fan drive assembly from
vehicle at this time.
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. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
7 - 86
ENGINE
DR/DH