Cooling System Description

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.

Coolant Description
This vehicle has a newly developed engine coolant. GM Goodwrench DEX-COOL was developed to last for 240,000 km (150,000 miles) or 5 years, whichever occurs first. Follow the instructions in Draining and Filling Cooling System. Make sure only GM Goodwrench DEX-COOL (silicate-free) or Havoline DEX-COOL is used when coolant is added or changed.
A 50/50 mixture of DEX-COOL and water will provide the following protection:

Notice: Pure coolant can be added to raise the boiling point of the coolant, but too much will affect the freezing point. Do not use a solution stronger than 70 percent, as the freeze level rises rapidly after this point. Pure coolant will freeze at -22°C (-8°F).

- Give freezing protection down to -37°C (-34°F).
- Give boiling protection up to 129°C (260°F).
- Protect against rust and corrosion.
- Help keep the proper engine temperature.
- Let the warning lights and gauges work correctly.