Cooling System: Description and Operation

Cooling System Description


General Description

The cooling system consists of the radiator, radiator cap, reservoir, hoses, coolant pump, two electric motor driven cooling fans, thermostat, and suitable passages for coolant circulation through the engine.


Cooling Fans

The cooling system utilizes two plastic fans. The right side fan is 320 mm (12.6 in.) in diameter an the left side fan is 410 mm (16.1 in.) in diameter. There are two fixed fan speeds which are determined by information based on engine coolant. A/C high pressure refrigerant temperatures, and vehicle operating conditions. Both fans are commanded "ON" at a calibrated engine coolant or A/C high pressure refrigerant temperature threshold. Fan power increases as engine or refrigerant temperatures increase and reaches full power at higher calibrated engine coolant or A/C high pressure refrigerant temperature.


Cooling System Circulation

The front engine mounted coolant pump is belt driven. Coolant from the radiator outlet (lower right side of radiator) flows to the coolant pump inlet and is pumped through coolant passages in the crankcase and into cavities surrounding the cylinder liners. Coolant then flows through holes in the cylinder head gaskets into the cylinder head coolant passages. Passages in the intake manifold direct the coolant to the thermostat at the right rear of the manifold. When the thermostat is closed (cold engine), the coolant is prevented from returning to the radiator and is recirculated for quick engine warm up. Once the engine is sufficiently warm, the thermostat opens and coolant flows to the inlet tank on the top left side of the radiator and is cooled as it flows across the horizontal core tubes to the outlet tank on the right side of the radiator, completing the cycle.