I have a 2000 Maxima that I love. It only has around 130,000 miles on it. I have had the cooling system flushed when required. Later had to replace a bad radiator. Last year on my way back from a trip to Michigan I noticed that the temp gauge was going up and got a little worried. It went up but never overheated. From that time on the temp gauge was always higher. Prior to last year the temp gauge never went halfway between hot and cold but it does now. I took it to the dealer and they couldn't find anything wrong. I had someone change the thermostat out--no change. The dealer is willing to keep looking for the problem but have said it could be a hundred things and the cost seems quite high. I'd like to find out what is wrong with it and fix it since otherwise the car is great. Also, this winter when driving to the mountains I had no problem except with mountain passes where the temp gauge would go up to about 90% (between hot and cold) but it never overheated. No, I don't smell coolant in the car and have never felt any coolant in the car carpet either. The temp gauge also does not change driving in town in stop and go traffic or anything--it's only going up mountain passes and traveling at high speeds for extended periods of time. No, there is no coolant leaking on the ground ever but of course, some coolant does seem to "disappear".

 

well I'm not saying you don't have a problem but thin mountain air will make your car act differently. going halfway between hot and cold is normal operating temp, you can try to burp your cooling system to make sure there is no air in it(several threads on the org can explain how this is done).

 

Hi, I'll try that but the problem started randomly--not after any type of service and I have driven it to the mountains since I got it with no problems. I had driven it on several long trips with no problems. My temp gauge did not read in the middle when I got this car--but has since moved there and since then I have had problems.

 

Maybe you should see if anything is wrong with your oil pump. It seems that problem might be your engine actually overheating and not a failure by your cooling system to cool the engine. High speed driving should in a normal situation make your cooling system work more efficiently due to increased air flow versus a stop and go situation.