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

The cooling system consists of the following components:

Cooling system operation requires the proper functioning of all components. The water pump draws coolant from the radiator and circulates the coolant through coolant jackets in the following areas:

The coolant is then directed back to the radiator where the coolant is cooled.

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

This vehicle has a newly developed engine coolant. GM Goodwrench DEX-COOL™ was developed to last for 166 000 km (100,000 mi) or 5 years, whichever occurs first. Follow the instructions in Draining/Filling Cooling System. Make sure only GM Goodwrench DEX-COOL™ (orange-colored, silicate-free) is used when coolant is added or changed.

A 50/50 mixture of ethylene glycol (GM Goodwrench 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).

The coolant level indicator module activates a lamp in the Driver Information Center (DIC) when the coolant in the radiator goes below a certain level. The module is mounted on the right side tank of the radiator. For diagnosis and location of the coolant level indicator module, refer to Electrical Diagnosis.

This switch activates a warning lamp in the Driver Information Center (DIC) if the engine overheats. With optional instrumentation, a temperature gauge replaces the warning lamp and a transducer replaces the temperature switch. For location and diagnosis of the switch, refer to Temperature Lamp Switch in Electrical Diagnosis.

The throttle body coolant system uses pipes and hoses to divert coolant to the throttle body. Coolant flows through the throttle body for cold weather starts and helps provide a smooth idle until the engine reaches operating temperature.

A deflector redirects air flow. Deflectors are installed under the vehicle and redirects the air flow beneath the vehicle to flow through the cooling system and increase radiator cooling.

Air baffles are used to direct air into the radiator and A/C condenser. Air seals ensure that air passes through, and does not bypass, the radiator and the A/C condenser. A missing, damaged, or incorrectly installed baffle or seal may cause the engine to overheat.

The coolant drain hole plug is on the front (3.1L) and rear (3.1L and 3.4L) of the engine block. On the 3.8L (L36), the coolant drain hole plug is on the right side and the left side of the engine block. When you completely drain the cooling system, remove the plugs.

The coolant pump is belt-driven. Coolant from the radiator outlet flows to the coolant pump inlet and is then pumped through coolant passages in the cylinder block and then into the cavities that surround the cylinder liners. Coolant then flows through holes in the cylinder head gaskets into the cylinder head coolant passages and into the throttle body coolant system. Passages in the intake manifold direct the coolant to the thermostat at the rear of the manifold. When the thermostat is closed, the coolant is prevented from returning to the radiator and is recirculated for quick engine warm-up.

Once the engine sufficiently warms, the thermostat opens and 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 tanks on the right side of the radiator. This completes the coolant flow cycle.

Problems not requiring disassembly of the cooling system:

Problems requiring disassembly of the cooling system: