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 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.
| CAUTION | Internal radiator pressure must not exceed 138 kPa (20 psi) as damage to radiator may result. |
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. Install 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.
| CAUTION | 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. |
Connect the water supply hose and air supply hose to 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 Replacement, see THERMOSTAT-ENGINE COOLANT . Connect the radiator hoses. Refill the cooling system with the correct antifreeze/water mixture. Refer to DESCRIPTION . Refer to Refilling the Cooling System, see COOLING-FILLING COOLING SYSTEM .
DRAINING
| WARNING | Do not open the radiator draincock with the system hot and under pressure. Serious burns from coolant can occur. |
Note. Drain, flush, and fill the cooling system at the mileage or time intervals specified in the MAINTENANCE SCHEDULE. Refer to DESCRIPTION . If the solution is dirty, rusty, or contains a considerable amount of sediment; clean and flush with a reliable cooling system cleaner. Care should be taken in disposing of the used engine coolant from your vehicle. Check governmental regulations for disposal of used engine coolant.
- Position a clean collecting container under draincock location.
- Without removing the pressure cap and with system not under pressure, turn draincock counterclockwise to open.
- The coolant reserve bottle should empty first, then remove the pressure cap.
- If coolant reserve bottle does not empty first: Check condition of the pressure cap and cap seals. Check for kinked or torn overflow hose from filler neck to reserve bottle.
- Allow cooling system to drain completely.