1994 GMC Safari Owner's Manual - Page 247

Radiator Pressure Cap ~ NOTICE: Your radiator cap is a psi (105 kPa) pressure-type cap and 15 must be tightly installed to prevent coolant loss and possible engine damage from overheating. Be sure the arrows cap on the line up with the overflow tube on the radiator filler neck. When youreplace your radiator pressure cap, an AC@cap is recommended. See "Service Replacement Part and Filler Recommendations" in the Index. Thermostat Engine coolant temperature is controlled by a thermostat in the engine coolant system. The thermostat stops the flow of coolant through the radiator until the coolant reaches a preset temperature. When youreplace your thermostat, an AC@thermostat is recommended. 6-29