I read a post here with this problem but now I can't find it to save my life.
I just bought a 98 Millenia with about 68K on it.
I recently drove about 220 miles one way and at the end of the trip it seemed like the engine was really hot and stayed that way for several hours after I stopped. The temp gauge never went above the middle of its range but I could hear a sound like the rods were clunking around when I was driving at low speed (through the parking lot). I assumed it might be because the oil had been thinned out by high temp?
It seems like the fans aren't coming on except when the A/C is turned on.
I changed the coolant temp sensor but the fans still don't seem to run when the A/C is off.
****GET THAT CHECKED OUT ASAP!!!!!!! The fans should be working when the temp gets above the mid mark, If the previous owner overheated the car the heads may be warped which will cause the car to overheat all the time. Mind you this is a very costly repair. With warped heads the car seems to run fine but it is not. Also have the cooling system checked , Incorrect level or air in system will cause the car to run hot.
I will have it checked if I can't figure it out. Can you think of a reason why the fan wouldn't run except when the AC is on? I don't think that it's the relay since the fan wouldn't come on with the AC if the relay was bad.
You would really have to overheat the engine alot before the heads warped, and maybe even throw a bucket of cold water or drive threw a big puddle while the engine was overheated to warp/crack them.
Usually what would happen before that would be the head gaskets would blow. Then steam/water would seep out of the gasket and steam up the engine compartment, also steam/water could seep into the combustion chamber where you would then see it coming out of the exhaust pipe and could potentially damage the pistons if alot of water was pouring in.
Hopefully that is not the case with this person's Millenia, it's probably overheating because of one of the other reasons.
I have a question about overheating. About 6 months ago, my car overheated due to a hose leaking. I've replaced the hose, but now the temp. will come up to 3/4 every now and again (very random). The fluiod level is full and I can't figure out why it's doing this. Any suggestions?