I didn't have any problems with the cooling system until the hose connection on top side of the radiator broke the other day. I replaced the radiator and added new coolant mixture. According to the instuctions I should fill the radiator while bleeding the air out of the system. I have done this 4 times. Still the coolant in the radiator is cool while the coolant in the engine is hot. Both should be on the warm side. Maybe the thermostat is bad. Not sure at this point. How do I check it? Frustrating.