GM Service Manual Online
For 1990-2009 cars only

Coolant Recovery Reservoir

A recovery-type cooling system is standard on these vehicles. The system is designed to maintain the proper engine operating temperatures. During vehicle use, the coolant heats and expands. The portion of the fluid displaced by this expansion flows from the radiator into the see-through, plastic coolant recovery reservoir. The reservoir is connected to the radiator with a hose. When the system temperature drops, the coolant is drawn from the recovery reservoir back into the radiator from the suction created by the coolant concentration. This keeps the desired level of coolant in the radiator at all times, resulting in increased cooling efficiency. When the system is cold, the coolant level should be at or above the COLD mark on the recovery reservoir.