Commander 4WD V8-4.7L VIN N (2006)
Water Pump: Testing and Inspection
WATER PUMP
LOOSE IMPELLER - 3.7L/4.7L/5.7L ENGINES
NOTE: Due to the design of the 3.7/4.7L/5.7L engine water pumps, testing the pump for a loose impeller must be done by verifying coolant flow in
the radiator. To accomplish this refer to the following procedure.
DO NOT WASTE reusable coolant. If solution is clean, drain coolant into a clean container for reuse.
1. Drain coolant until the first row of cores is visible in the radiator 4.7L Engine.
2. Leaving the radiator cap off, start the engine. Run engine until thermostat opens.
3. While looking into the radiator through the radiator fill neck, raise engine rpm to 2000 RPM. Observe the flow of coolant from the first row of
cores.
4. If there is no flow or very little flow visible, replace the water pump.
INSPECTING FOR INLET RESTRICTIONS
Inadequate heater performance may be caused by a metal casting restriction in the heater hose inlet. DO NOT WASTE reusable coolant. If solution is
clean, drain the coolant into a clean container for reuse.
WARNING: Do not loosen the radiator draincock with the system hot and under pressure. Serious burns from the coolant can occur.
1. Drain sufficient coolant from the radiator to decrease the level below the heater hose inlet. On 4.7L engines this requires complete draining.
2. Remove the heater hose.
3. Inspect the inlet for metal casting flash or other restrictions.
