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No responsisbilty is accepted for anyone attempting this procedure by following the steps contained in these pages. This is intended as a guide only and all usual precautions should be heeded when attempting work on a motor vehicle. I cannot be held responsible for any damage sustained as a result of using these pages.


The coolant afterrun system only operates when the ignition is switched off. If the temperature of the coolant at the afterrun sensor exceeds 110 degrees, the afterrun switch will trigger the afterrun relay. This in turn will send a signal to operate the cooling fan at speed #1 and the afterrun pump will pump coolant in reverse to normal coolant direction. This sequence will continue until the coolant temperature at the afterrun sensor reaches 97 degrees or a time of 10 minutes has elapsed.

First step is to raise the bonnet of the car.

The afterrun temperature sensor is located on the water rail
below the inlet manifold. The picture shows two sensors.

The large sensor (2) is often referred to as the multi function temperature sender (MFTS).

The smaller of the two sensors (1) is the afterrun sensor.
To test operation of the afterrun system, the two wires should be removed from the afterrun sensor and touched together.

1. The main radiator fan should start running at #1 speed.
2. The auxiliary water pump pictured right should also start.

If the fan does not start check the following:

Wiring from fan to resistor pack.
Resistor pack and connectors condition.
Afterrun system relay.

If the fan does start but the system is known to operate incorrectly, the sensor should be replaced.