Cooling System: Description and Operation

DESCRIPTION
The engine coolant:
1. Flows through the radiator tubes and is cooled by air passing over the cooling fins (assisted by the cooling fan as necessary).
2. Is then circulated from the radiator outlet tank (8054) through the radiator coolant recovery reservoir (8A080) which is pressurized to continuously separate the air from the cooling system.
3. Flows from the radiator coolant recovery reservoir through the engine, heater core (18476) and water pump (8501), then returns to the radiator (8005) through the water hose connection (8592).

COMPONENTS
The engine cooling system includes the following:
- Electric cooling fan motor and fan blade (8600), activated by the variable control relay module.
- Heater water hoses (18472).
- Oil cooler (6A642).
- Radiator (8005).
- Radiator coolant recovery reservoir (8A080) located beside the radiator, aids in maintaining the correct volume of engine coolant.
- Upper radiator hose (8260) and lower radiator hose (8286).
- Water pump (8501).
- Water thermostat (8575).





COOLANT RECOVERY SYSTEM
The 4.6L engine is equipped with a pressure relief cap.
WARNING: ON VEHICLES EQUIPPED WITH THE 4.6L ENGINES NEVER REMOVE THE PRESSURE RELIEF CAP UNDER ANY CONDITIONS WHILE THE ENGINE IS OPERATING. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE AND/OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE COOLING SYSTEM, USE EXTREME CARE WHEN REMOVING THE PRESSURE RELIEF CAP FROM A HOT COOLING SYSTEM. WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE PRESSURE RELIEF CAP AND TURN IT SLOWLY UNTIL PRESSURE BEGINS TO RELEASE. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN CERTAIN ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE PRESSURE RELIEF CAP (STILL WITH A CLOTH), TURN AND REMOVE PRESSURE RELIEF CAP.

The coolant recovery system operates as follows:
^ The system uses a 110 kPa (16 psi) pressure relief cap, a plastic radiator coolant recovery reservoir (8A080).
^ When coolant in radiator expands to the overflow point, it passes through the pressure relief cap and into the radiator coolant degas bottle. When coolant in radiator cools down and contracts, it pulls coolant from the radiator coolant recovery reservoir through a spring-loaded vacuum relief valve in the pressure relief cap and back into the radiator.
- Extra coolant is carried in the radiator coolant degas bottle.
- Any air bubbles trapped in the cooling system are vented in the radiator coolant degas bottle.

BLOCK HEATER
The optional block heater (6A051) is designed to keep the engine coolant warm during cold weather to aid in cold starting. It consists of:
1. Electrical heating element installed in one of the core plug openings in the cylinder blocks (6010).
2. Electrical cable which plugs into a standard 110-volt AC electrical outlet.
Refer to Engine for repair procedures.