For 1990-2009 cars

### General 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 coolant pump

• | A thermostat

• | Two electric engine cooling fans

• | An accessory drive belt(s)

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.

### Long Life Coolant

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 this protection:

### Cooling System Circulation

The front engine-mounted coolant pump is belt driven. Coolant from the radiator outlet flows to the coolant pump inlet, and the coolant is pumped through coolant passages in the crankcase 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.

### Throttle Body Coolant

The Sequential Fuel Injection (SFI) system has coolant passages in the throttle body. The coolant flow improves cold driveability.

### Radiator Air Baffle Assemblies, Deflectors, and Seals

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.