- If the engine is hot, allow the engine coolant to cool to 86°F (30°C).
- Remove the cap on the radiator expansion tank.
- If equipped, remove the front underbody protection panel.
- Place a suitable coolant drain pan under the radiator drain plug. Remove the plug and allow the coolant to drain and reinstall the plug with a new gasket.
- Place a suitable coolant drain pan under the right rear portion of the engine and remove the engine block drain plug. On 6-cylinder engines, the plug is located below the exhaust header for cylinders Nos. 4 and 5. On 4-cylinder engines, the drain plug on the right side of the block toward the rear of the engine. Reinstall the drain plug using a new gasket.
- Use a 50 / 50 mixture of an approved coolant and if available, distilled water. Do not exceed a solution of coolant to water greater than 60%.
- Switch the ignition ON , set the heater control to maximum temperature and set the blower to run on low speed.
- If the coolant expansion tank does not have a bleed screw the bleeding of the cooling system occurs during refilling. To assist with the removal of any trapped air pockets, squeeze the lower radiator hose during the refilling process.
- If the coolant expansion tank has a bleed valve, loosen the valve. Inspect the coolant pipes at the front of the engine for the presence of an additional bleed valve which is standard equipment on all M52 engines and loosen that bleed valve.
- Fill the cooling system slowly, closing the bleed screws once the fluid is free of any air bubbles.
- Start the engine, and with the reservoir cap removed give the engine 3 or four short bursts of throttle between 4,500-5,000 RPM, but do not run the engine longer than 30 seconds, otherwise the coolant will heat up and expand.
- Top off the coolant level, install the reservoir cap and if equipped, make sure all the bleed screws are closed. Start the engine and allow the engine to reach operating temperature. Do not remove the coolant fill cap until the engine coolant has cooled to 86°F (30°C).
- Allow the engine to cool, inspect the coolant level and top off as necessary.
With the use of electrically actuated heater valves and bi-zone heater cores, it is not easy or advisable to cut hoses to mount a flushing tee. Drain the system, add clear water, bleed the system and run the engine to flush the system of old coolant. Drain the system, add fresh coolant and bleed the system. This will get rid of most of the old coolant and keep the cooling system in good shape. It is important to change the coolant on a regular basis, every 2 years, as this will prevent corrosion from building up and creating the need for cleaning the cooling system.