GM Service Manual Online
For 1990-2009 cars only

Coolant Recovery Reservoir

Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

A vent hose connects the "see-through" plastic reservoir to the radiator. During vehicle use, the coolant heats and expands. The displaced coolant, resulting from fluid expansion, flows from the radiator into the coolant recovery reservoir. After running the vehicle and shutting off the engine, the coolant cools and contracts. Vacuum then draws the displaced coolant back into the radiator. Because the system maintains the desired level of coolant in the radiator at all times, this results in increased cooling efficiency.

Keep the coolant level between the ADD and the FULL marks on the recovery reservoir. These marks are approximately one liter (one quart) apart. Use a 50/50 mixture of the ethylene glycol antifreeze and distilled water in order to keep the system at the FULL mark when the system is hot.

Diesel Surge Tank

The diesel engine uses a cooling system with a surge tank. The pressure cap for the diesel engine differs from the gasoline engine pressure cap. The cap is on the surge tank. The diesel engine uses a pressurized surge tank. Coolant circulates through the surge tank. The surge tank provides the following features:

    • Allows the escape of any air in the system
    • Provides room for coolant expansion when the coolant is hot