GM Service Manual Online
For 1990-2009 cars only

The cooling system maintains engine temperature at an efficient level during all engine operating conditions. The cooling system consists of the following components:

    • A radiator
    • A radiator pressure cap
    • A coolant recovery reservoir
    • A water pump
    • A thermostat
    • Two electric engine cooling fans
    • A drive belt

A thermostat controls coolant circulation. The thermostat remains closed until the engine reaches normal operating temperature.

When the engine is cold, coolant does not circulate through the radiator. This allows for faster engine warm-up.

When the engine reaches normal operating temperature, the thermostat opens, and the coolant circulates through the radiator in order to keep the engine from overheating.

These engines have a closed cooling system. This means you can add coolant to the coolant recovery reservoir without removing the pressure cap from the radiator.

Cooling System Circulation

The front engine-mounted water pump is belt driven. Coolant from the radiator outlet flows to the water pump inlet, and the coolant is pumped through coolant passages in the engine block and into the cavities surrounding the cylinders. 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. When the thermostat is closed, the coolant is prevented from returning to the radiator, and the coolant is recirculated for quick engine warm-up.

When the engine reaches operating temperature, the thermostat opens, and the coolant flows to the inlet tank on the top left side of the radiator. The coolant is cooled as the coolant flows across the horizontal core tubes to the outlet tank on the right side of the radiator. This completes the coolant flow cycle.