Cleaning/Reverse Flushing

Cleaning/Reverse Flushing


Internal radiator pressure must not exceed 138 kPa (20 psi) as damage to the radiator may result.


On vehicles equipped with a heater water control valve, be sure the heater control valve is closed (heat off). This will prevent coolant flow with scale and other deposits from entering the heater core.

Cleaning

Drain the cooling system and refill with water. Refer to=> [ Cooling System Draining and Filling ] Cooling System Draining and Filling. Run the engine with the radiator cap installed until the upper radiator hose is hot. Stop the engine and drain the water from system. If the water is dirty, fill the system with water again, run the engine and drain the system. Repeat this procedure until the water drains clean.

Reverse Flushing

Reverse flushing of the cooling system is the forcing of water through the cooling system. This is done using air pressure in the opposite direction of normal coolant flow. It is usually only necessary with very dirty systems with evidence of partial plugging.

Reverse Flushing the Radiator

Disconnect the radiator hoses from the radiator inlet and outlet. Attach a section of the radiator hose to the radiator bottom outlet fitting and insert the flushing gun. Connect a water supply hose and air supply hose to the flushing gun.

Allow the radiator to fill with water. When the radiator is filled, apply air in short blasts. Allow the radiator to refill between blasts. Continue this reverse flushing until clean water flows out through the rear of the radiator cooling tube passages.

Reverse Flushing the Engine

Drain the cooling system. Refer to => [ Cooling System Draining and Filling ] Cooling System Draining and Filling. Remove the thermostat housing and thermostat. Reinstall the thermostat housing. Disconnect the radiator upper hose from the radiator and attach the flushing gun to the hose. Disconnect the radiator lower hose from the water pump and attach a lead away hose to the water pump inlet fitting.

Connect the water supply hose and air supply hose to the flushing gun. Allow the engine to fill with water. When the engine is filled, apply air in short blasts, allowing the system to fill between air blasts. Continue until clean water flows through the lead away hose.

Remove the lead away hose, flushing gun, water supply hose and air supply hose. Remove thermostat housing and Install thermostat. Install the thermostat housing with a replacement gasket. Refer to => [ Thermostat ] Service and Repair. Connect the radiator hoses. Refill the cooling system with the correct antifreeze/water mixture. Refer to => [ Cooling System Draining and Filling ] Cooling System Draining and Filling.

Chemical Cleaning

In some instances, use a radiator cleaner before flushing. This will soften scale and other deposits and aid flushing operation.


Follow the manufacturers instructions when using these products.