2004 Hyundai Elantra 2.0 L thermostat and radiator repair issues.
Hello, I just replaced a radiator and thermostat on my sister in laws 2004 Hyundai Elantra sedan. The car had a leaking radiator and while replacing it I also replaced the thermostat. The car has less than 70k on it. It was owned by her dad and given to her instead of being ripped off on a trade in. Garage kept and very good shape other than the radiator issue has never had any mechanical issues before. Never been hot either as when he noticed the leak he parked it and purchased another car.
So after replacing the parts and putting in water to test for leaks I noticed that though the top radiator hose got warm the bottom never did. Even after running it for twenty minutes with the AC and with the heater on. The temp gauge indicates normal operating temp and there are no visible leaks.
The bottom hose stayed use cold. The water in the radiator stayed ice cold. The fans kicked on after ten minutes or so but the thermostat never opened up to let the water from the motor exchange with the water that's been sitting in the radiator.
I even ran it to the store and checked the hose after getting there and still had not opened up. The top hose hot and the bottom ice cold. The gauge would go to a little more than half way which I'm told is about normal. It even dropped once after hitting the 5/8 position down to about the 3/8 point telling me that the thermostat finally opened up but checked the bottom hose and still cold as ****.
Took the thermostat back out. Purchased another one and put it back in and ran same type of test run with just water and after thirty minutes of idling with heater on the top hose hot as **** the bottom cold as ice. I see no air valve to release pressure while adding coolant and am worried that I'm missing something here. Please if any one has any advice for me on this I would appreciate it as this car has been well maintained and would hate to blow the motor when there is obviously so much life left on it.