Engine Overheating Issues

Hey guys/gals,

So I’m having an overheating issues that I can’t seem to figure out. My car seems to overheat sometimes while sitting at idle after a fairly long drive. It doesn’t go all the way in to the H, but maybe 3/4 of the way there. I turn on the heater and almost immediately it goes back down to right before 1/2. I tested the fan and it turns on. I tested the fan relay, and the fan turns on, however, I don’t hear it turn on when my car starts to overheat. So far I’ve replaced the the ECT switch, the thermostat, the radiator/radiator cap, and about 10K miles ago I replaced the water pump. I’ve also bled the system to make sure there were no air bubbles. I’ve noticed that sometimes, the lower radiator hose is warm to the touch, not hot like the upper radiator hose. Any ideas as to what else it could be?

Any help would be greatly appreciated!


I think I might have figured it out. I just tested the old thermostat, which is the same as the new one I got. The old one only has about 5k miles, so I figured it should still be relatively good (I replaced it again because I replaced the radiator). It looks like it doesn’t START to open until about 192°F, and it’s not fully open until about 205°F. According to the FSM it should start opening at 169°F - 176°F and should be fully open by 194°F. That might explain why my gauge goes 3/4 of the way and not straight to the H. Would also explain why the upper hose is hot and the lower one is much cooler.

What do you guys think?