For 1990-2009 cars

### Cooling System

The cooling system maintains engine temperature at an 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 subsystem, cooling fans, thermostat and housing, water pump, and drive belt.

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 heads, 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.

### 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 returning 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.

### Cooling Fan Relay

For information and diagnosis of the cooling fan relay, refer to the Engine Electrical and the Engine Controls sections of the manual.

### Temperature Gauge

The temperature gauge replaces the warning lamp. The temperature switch is replaced with a transducer. For the location of, and the diagnosis of the temperature gauge, refer to Engine Electrical.

### Coolant Temperature Fan Switch

The switch regulates voltage to the coolant fan relay, which operates the fan whenever the engine coolant temperature exceeds 110°C (230°F). For location and diagnosis, refer to Engine Electrical.