Coolant Bleed Procedure

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Cooling System Bleed Procedure

Electric Waterpump Cooling System

This bleed procedure works on all vehicles with the N52, N51, N52K and N54 engine, operating with electric cooling water pump. The coolant flows through the electric water pump cooling the motor and electronics. Coolant lubricates the bearings in the pump. When servicing the pump, care must be taken not to run the pump without coolant. If the pump is removed during a repair, it should be filled with coolant to prevent the pump from seizing.


The procedure begins by connecting a battery charger to the vehicle. Fill the system with coolant via the reservoir until the proper level is achieved. It may be necessary to remove a bleeder screw on the reservoir when initially filling the cooling system on some reservoirs. Install the cap and bleeder screw if present, on the reservoir. Turn on the ignition (do not start car), set the heat to maximum and the blower on the lowest setting. Begin by pressing the accelerator pedal to the floor for at least 10 seconds; be sure NOT to start the engine. Release the accelerator pedal and within a moment, the pump can be heard during activation. While the bleed procedure is being performed, inspect for leaks. The procedure can be repeated several times as needed, turning the ignition off for 5 minutes between each bleed procedure.



Conventional Waterpump Cooling System

The procedure to bleed the cooling system with a conventional waterpump requires some preconditions prior to filling the system with coolant. With a charger connected to the vehicle and the ignition on, set the heater to maximum temperature and the fan on the lowest setting. Now remove the bleeder screw next to the fill cap, on some systems their may be more than one bleeder screw. Begin filling the system with coolant until coolant emerges from the bleeder screw holes. Maintain a level just above the bleeder screw hole, when their are no more bubbles coming from the bleeder screw hole, insert the bleeder screw. With a baster, draw out coolant from the reservoir until the appropriate amount of coolant is in the reservoir. Start and run the engine until operating temperature is acheived. Shutoff the engine and allow to cool before checking to verify the correct coolant level.

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