I just noticed that my lower radiator hose is still cool to the touch, even after a long drive. The upper hose is hot though. The truck runs cool , according to the temp gauge. Yesterday I drained the old coolant from the radiator and engine block. When I went to refill it, it only held 10 quarts instead of 17.3. I know it's not possible to drain 100% of the old coolant, but shouldn't it hold more than about 10 quarts? Is all this normal, or should I have it checked out?

Dave
1998 4.2 v6
55,000 miles

 

I think your thermostat is stuck open.

The flow of coolant is from the engine, through the upper radiator hose, through the radiator, then through the lower radiator hose and back to the engine. The thermostat is not regulating the coolant flow so the engine and coolant never heat up.

I don't know if you did this or not, but after refilling the cooling system you need to run the heater on high to help remove air from the system.