Flushing

When replacing coolant because of excessive rust or dirt, the system should be vigorously flushed to break up and remove deposits of sludge, rust, and foreign matter.

If closed-circuit pressure flushing equipment is not available, the cooling system may be flushed with clean water as follows:

1. Drain the cooling system.
2. Install and tighten the front and rear cylinder block drainplugs securely.
3. Close the radiator draincock at the bottom of the radiator inlet tank.
4. If equipped with a rear heater, install and secure hoses for the rear heater.
5. Fill radiator with water.

NOTE: Fill until water starts to drip from the radiator air relief plug, and close the plug. Tighten the radiator air relief plug to 20-26 Nm (14-20 ft. lbs.).

6. Install and tighten the engine air relief plug to 20-26 Nm (14-20 ft. lbs.).
7. Fill radiator and radiator coolant recovery reservoir with water.
8. Install radiator cap.
9. Start the engine.

NOTE: If the vehicle is equipped with a rear heater, turn the rear temperature switch to full WARM and turn the rear fan ON.

10. Warm up the engine until lower radiator hose becomes warm, then rev the engine 2 or 3 times under no-load.

NOTE: Watch temperature gauge closely. If gauge begins to rise above normal, stop engine.

11. Stop the engine and allow it to cool down.
12. Drain water.
13. Repeat the procedure until clear water drains from the radiator.
14. Connect a high-pressure hose to the lower radiator hose outlet. Back-flush the radiator and engine until water runs clean from the lower radiator hose. Turn water on and off several times, pulsing the flow to help loosen sludge deposits.

CAUTION: Flushing water flow must be limited so that pressure inside the radiator does not exceed 103 kPa (15 psi).

15. When the system drains clear water, unplug the radiator overflow hose. When clear water flows from the radiator overflow hose, replug it.
16. Before connecting the cooling system hoses disconnect all of the hoses installed for the radiator and engine backflush procedure. The heater loop must be back-flushed separately to prevent loosened sediment from lodging in the heater core.