Description: This 05 Chevrolet Malibu with the 3500 series engine, had low temp heater and low running coolant temperatures. The coolant reserve was full, but within 2 mins. after startup the upper radiator hose was getting warm because of coolant bypassing the defective thermostat. The thermostat should keep the engine coolant confined between the engine and the heater core, until coolant temperature reaches a 195* F. Which takes a few minutes. Only after this high temperature is reached should the coolant flow out the upper radiator hose. And any excess heat is then dissipated through the radiator. At this temperature the passenger compartment is able to maintain a comfortable environment, against freezing conditions. Providing that the other systems are adequate.
Post time: Jun-21-2017