upper radiator hose on 2004 Dodge Grand Caravan

Have 04 dodge grand caravan 3.3 engine, Diving along 65 to 75 miles per hour,heat gauge shoots up to very very hot, get out check engine,heat gun says 170to180.and upper radiator hose is closed . do you know what causes this, I have changed thermasat,coolent, and had radiator rodded out and changed heat temp sensor, does anyone have answer ?

by in Turlock, CA on January 30, 2009
1 answer
ANSWER by , February 01, 2009
In rare instances, the water pump impeller may be slipping on the shaft. At the speed you indicated, the air flow through the radiator is sufficient to maintain coolant temp provided there are no air flow restrictions. Make sure the belts are routed properly. Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine at running and at operating temperature, the high pressure inlet tank runs full and the low pressure outlet tank drops, resulting in cooling system aeration. Aeration will draw air into the water pump resulting in the following: High reading shown on the temperature gauge. Loss of coolant flow through the heater core. Corrosion in the cooling system. Water pump seal may run dry, increasing the risk of premature seal failure. Combustion gas leaks into the coolant can also cause the above problems.