the pump. Reverse-flushing is accomplished by hot water, under air pressure, being forced through the cooling
system in a direction opposite to the normal flow of coolant, loosening and forcing scale deposits out.
The radiator is reverse-flushed as follows:
1. Remove the radiator inlet and outlet hoses and replace the radiator cap.
2. Attach a hose at the top of the radiator to lead water away from the engine.
3. Attach a hose to the bottom of the radiator and insert a flushing gun in the hose.
4. Connect the water hose of the gun to the water outlet and the airhose to the compressed air outlet.
5. Turn on the water and, when the radiator is full, turn on the air in short blasts, allowing the radiator to
fill between airblasts.
Apply air gradually. Do not exert more than 30 psi
(207 kPa) air pressure. Too great a pressure may
rupture a radiator tube.
6. Continue flushing until only clean water is expelled from the radiator.
The cylinder block and cylinder head water passages are reverse-flushed as follows:
1. Remove the thermostats and the water pump.
2. Attach a hose to the water inlet of the cylinder block to drain the water away from the engine.
3. Attach a hose to the water outlet at the top of the cylinder block and insert the flushing gun in the
4. Turn on the water and, when the water jackets are filled, turn on the air in short blasts, allowing the
engine to fill with water between airblasts.
5. Continue flushing until the water from the engine runs clean.
If scale deposits in the radiator cannot be removed by chemical cleaners or reverse-flushing as outlined above,
it may be necessary to remove the upper tank and rod out the individual radiator tubes with flat steel rods.
Circulate water through the radiator core from the bottom to the top during this operation.
Miscellaneous Cooling System Checks
In addition to the above cleaning procedures, the other components of the cooling system should be checked
periodically to keep the engine operating at peak efficiency. The cooling system hoses, thermostats, and
radiator pressure cap should be checked and replaced if found to be defective.
When water connection seals and hoses are installed, be sure the connecting parts are properly aligned and the
seal or hose is in its proper position before tightening the clamps. All external leaks should be corrected as
soon as detected.
The fan belt must be checked and adjusted, if necessary, to provide the proper tension and the fan shroud must
be tight against the radiator core to prevent recirculation of air which may lower the cooling efficiency.
When the engine cooling or lubricating system becomes contaminated, it should