Water pump. Water pump bypass-4.7L

Water pump

DESCRIPTION

The water pump is located on the engine front cover, and has an integral pulley attached (Fig. 8).

The water pump impeller is pressed onto the rear of a shaft that rotates in a bearing pressed into the water pump body. The body has a small hole for ventilation.

The water pump seals are lubricated by antifreeze in the coolant mixture. Additional lubrication is not necessary.

Fig. 7 Radiator-Typical

1 - RADIATOR

2 - A/C CONDENSER (IF EQUIPPED)

3 - TRANSMISSION AUXILIARY OIL COOLER

Fig. 8 Water Pump Location-Typical

1 - WATER PUMP BYPASS HOSE

2 - FAN BLADE ASSEMBLY

3 - VISCOUS FAN DRIVE

4 - WATER PUMP AND PULLEY

OPERATION

A centrifugal water pump circulates coolant through the water jackets, passages, intake manifold, radiator core, cooling system hoses and heater core, this coolant absorbs the heat generated when the engine is running. The pump is driven by the engine crankshaft via a drive belt.

Water pump bypass-4.7L

DESCRIPTION

The 4.7L engine uses an internal water/coolant bypass system. The design uses galleries in the timing chain cover to circulate coolant during engine warm-up preventing the coolant from flowing through the radiator. The thermostat uses a stub shaft located at the rear of the thermostat (Fig. 9) to control flow through the bypass gallery.

Fig. 9 Water/Coolant Bypass Flow and Thermostat- 4.7L Engine

1 - FROM HEATER

2 - FROM RADIATOR

3 - TO WATER PUMP

4 - ENGINE BYPASS

5 - THERMOSTAT

OPERATION

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 stub shaft enters the bypass gallery obstructing bypass coolant flow by 50%. This design allows the coolant to reach operating temperature quickly when cold, while adding extra cooling during normal temperature operation.