I just bought a car from a friend and they had told me that the head gasket was replaced ahead of schedule, which was good news because my suzuki's head gasket blew and I had a whole bunch of overheating problems. Well this is a 1999 Dodge Neon. I started the car after stopping about a half an hour to get lunch. When I started it, the temperature gauge went right to the halfway point, which I thought was odd since I just started it, but everything seemed to be fine. After work later this evening, I drove home and noticed that my temperature gauge was fluctuating, going from its original spot up towards H, back down, and back up again and so on. At one point, the gauge was all the way to the 3/4 mark closest to H. It still wasn't smoking or anything and I was almost home so I continued to drive. When I got home, I expected smoke to pour out of the engine, as I'd had this experience before with the previous car, but nothing happened. I turned the car off and opened the hood. Nothing seems out of the ordinary. No smoke, no leaks, nothing. What could possibly be wrong with this car?

Jenni. Your temp gauge that you see is called a receiver. The one attached to your engine is called a sender. Whatever that sender sees, touches, feels, is what you see on the dash.
If it sees coolant, it's a nice smooth transition from cold to warm to hot.
If it sees nothing but air, then coolant, then air, you get a fluctuating gauge like you see happening.
I suspect you need to have the cooling system purged ( I like to say burped) and then go from there.
We'll be here standing by.

Kitch,

Thank you so much for your answer. It was really clear and easy to understand, which I appreciate because I know nothing whatsoever about cars! It appears though that the problem is a lot simpler and something I had overlooked when I originally described it. I later noticed a sound that sounds like there is a pinhole leak somewhere and when we filled it back up with coolant, the gauge stayed the same but the coolant all seemed to run out of the placed where it's kept (sorry, drawing a blank.told you I knew nothing about cars!). So, I think there is a leak somewhere. Thanks again for your answer though!

Make sure you get this leak checked and fixed before you keep driving around. Driving with low coolant in a car like this can very easily cause the head gasket to go bad or ruin the head itself. It's worth taking the time and money to fix the leak now before it causes more trouble.

Good luck with this.

I hate to admit this to a public forum, but I really have no idea what I am talking about. The car is working fine now. We added coolant and because I am kind of paranoid with cars after my first one overheated and the head gasket blew, it looked to me like the coolant was leaking. But I had a friend check it and then drive it around and everything seems to be in good working order. Thank you, everyone, for your help! I really appreciate it!

I have to warn you some more... Cooling systems are closed systems. If you had to add coolant, there is a reason for this. It is highly probable that there is a leak or that the head and or gasket is bad despite the fact that is was supposed to have been fixed already. Neons have a bad track record when it comes to heads and gaskets.

The reservoir tank which stores your coolant has a minimum line and a maximum line on it. When it's hot, it will bleed off excess coolant past the radiator cap and store it in the tank.
While sitting overnight, the cooling system will have a negative pressure and draw some coolant back into the radiator through the cap from the tank.
The coolant MUST stay between these two lines at all times or you have a problem somewhere.
So keep a watchful eye on it. You have just passed cooling system 101, so Jenni, you DO know something about cars now don't you?

I have a question regarding the fluctuation of the cars tempature gauge. I started to notice a problem a week ago when I had been driving my grandson and my daughter around.

Until then I hadn't had any problems with this tempature gauge but that day after driving for about 30 minutes I noticed the gauge had risen almost to the maximum meaning the engine was over heating. I had left the engine on with the heater running as well. All the way home I was conscious of the gauge fluctuating between very hot and very cool, When I used the car after that day I still had some fluctuation but not so bad, but a few days later I again switched the heater on and as before the needle of gauge went straight to Red.

I have had the coolant system checked and it is not losing any coolant so does anybody have the answer. Am hoping it will be something easy to rectify.

I suspect phosphate scale has blocked some passages in the radiator. I would replace the radiator and refill with a 50/50 mixture of the proper antifreeze and distilled water. Read your Owner's Manual on how to properly refill the cooling system, in order to purge all air--this is extremely important on many cars these days.