Cooling System: Description and Operation

DESCRIPTION
The cooling system maintains engine temperature at In efficient level during all engine operating conditions. When the engine is cold the system cools slowly, or not at all, to allow the engine to warm up quickly.

The cooling system includes a radiator and coolant recovery sub-system, cooling fans, thermostat and housing, water pump, and drive belt.

OPERATION
Operation of the cooling system requires proper functioning of all components. Coolant is drawn from the radiator by the water pump and circulated through coolant jackets in the engine block, intake manifold, and cylinder head(s). and then directed back to the radiator where it is cooled.

This system directs some coolant through hoses to the heater core. to provide for heating and defrosting. A recovery reservoir is connected to the radiator to recover coolant displaced by expansion from high temperatures and maintain correct coolant level. As the coolant cools and contracts it is drawn back into the radiator by vacuum.

Coolant Recovery System
A recovery type cooling system is standard on all vehicles and is designed to maintain the engine at proper operating temperatures. As the vehicle is driven, the coolant is heated and expands. The portion of the fluid displaced by this expansion flows from the radiator into the recovery reservoir. When the system temperature drops, the coolant is drawn from the recovery reservoir back into the radiator by the suction created by the coolant contraction. Thus, the radiator is kept tilled with coolant to the desired level at all times, resulting in increased cooling efficiency.

Cooling System Circulation
The water pump is belt-driven. Coolant from the radiator outlet (lower right side of radiator) flows to the water pump inlet and is pumped through coolant passages in the cylinder block and into the cavities surrounding the cylinder liners. Coolant then flows through holes in the cylinder head gaskets into the cylinder head coolant passages and into the thermostat bypass system. Passages in the intake manifold direct the coolant to the thermostat at the rear of the manifold. When the thermostat is closed (cold engine), the coolant is prevented from resuming to the radiator and is recirculated for quick engine warm-up.

Once the engine has warmed sufficiently, the thermostat opens and coolant flows to the inlet tank on the top left side of the radiator. It is cooled as it flows across the horizontal core tubes to the outlet tanks on the right side of the radiator, completing the cycle.


Cylinder Block Plugs
For location of the coolant jacket plugs in the cylinder block, refer to the disassembled views in the Engine Mechanical. For removal and installation procedures. Refer to Engine Mechanical.