Cleaning/Reverse Flushing

Cleaning/Reverse Flushing


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


Follow the manufacturers instructions when using these products.

Cleaning

Drain the cooling system and refill with water. Run the engine with the radiator pressure cap installed until the radiator upper hose is hot to the touch. Shut off the engine and drain the water from cooling system. If the water is dirty, fill the system with water, run the engine and drain the system again. Repeat this procedure until the drained water clean.

Reverse Flushing

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

Reverse Flushing Radiator

Disconnect the radiator hoses from the radiator. Attach a section of the radiator hose to the radiator 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 Engine

Drain the cooling system. 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 the thermostat housing and install the thermostat. Install the thermostat housing with a replacement gasket. Refer to => [ Thermostat ] Service and Repair. Reconnect 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 the scale and other deposits and aid flushing operation.