I have a overheating problem with 1997 Neon. While idleing, temperature reaches normal and no overheating occurs (even when AC on at full blast). While driving, overheating occurs even with the ac off and at any speed. Replaced Thermostat & coolant temp sensor, with radiator cap off circulation of the coolant looks normal. No oil on the coolant, no white scum on the oil. The only thing that I have noticed is that one of the radiator cap seals is quite worn out. Will this cause an overheating problem????.

My '98 had a simular problem. Try a new cap first. But the system also
has a rheostat on the drivers side,just outboard of the radiator. I had to replace mine.
I hope this helps. Good luck. Did you try Neons.org for a answer ?

Take care ! Don

Just got a new radiator cap, have to wait until the car cools down to replace it. Never heard of the rheostat, will look into it. Thanks!!!!!

I'm new to the forums, however I have (and since fixed) this problem on my 95 4d highline and the fix was *rather* unconventional. The problem had to do with the radiator fan actually engaging at a fast enough speed/not engaging at all. Mind you, I'm using a 95 highline, wich means I've got an aluminum block SOHC (aluminum over heats like a mofo).

1. I cut the leads to the fan that go to the box, soldering a new constant ground lead that is connected to the battery screw.

2. I ran a live (hot, posative, whatever you want to call it) line from the positive terminal bolt to a switch (use metal, plastics will overheat and melt) I installed on the dash.

3. Last I ran a second live from the switch to the live lead on the fan.

This way when you get in the car you just turn on the switch then start the car. The downside, don't forget to turn on the fan or you'll overheat. The upside, you'll never overheat again and the problem is solved.

Just an unconventional solution to a common problem from what I understand.

A bad radiator cap can cause overheating. The higher the pressure, the higher the boiling point of a liquid. The radiator cap keeps that pressure in. If you have a bad gasket on the cap, it will let the pressure out, therefore reducing the boiling point of the coolant. The new cap should do it for ya. If that doesn't help, you may have to have the radiator flushed. It might be full of scale and other junk.

when it happened to me.. it was my radiator fan relay circuit..about 60$.. my fan wouldnt come on.. so i had to run the heat full blast to bring temp down. does your fan come on?

take it to the shop....