I was just drivng my car on the highway and had the A/c when i look down to see how much gas i have left i see that car is almost 260... I quickly turn off the A/c and it goes down to about 230.... It was about 95 outside and i was trying almost 30 mins... what can be wrong... i changed the coolant last year.. its never done this before....

 

Make sure there isn't anything (debris) blocking the radiator.

 

Unless you've converted it to a working gauge, the 99+ years had dummy gauges.

 

I checked under and nothing was stuck under there... also the batt gauge was almost on the red. i had the a/c radio on. and my temp guage has always work as far as i know.. always been around 200 to 210.. never heard anything about it being a dummy gauge

 

Yes, 98 was the last year that had an actual, working gauge. The 99 and newer ones "warmed" up to "normal" and then stayed there. They don't fluctuate because they do not tell you the real temperature.

I believe there is an actual idiot light that comes on if it really does start to overheat. But I would not trust that gauge.

 

Did u reciently have the A/C serviced?



Don

 

F-bodies do have a sort of "dummy" guage after '98, but they still will report an overheating motor. It's more of a de-sensitized guage if you will. If your thermostat isn't opening all of the way, that could be a source of the problem. Also, what kind of fluid did they use when you had it replaced? Did they just replace it or flush it? Might want to get the system flushed with all new coolant. There could be a bit of crud in there blocking the paths. Also, if your battery was in the red, either it's not holding a charge or your alternator might be on the way out. The electrical system also powers the fans. If the power was drained out of the system, the fans probably weren't spinning too fast. Just some thoughts on where to look....

 

I just remeber that it was flushed and that they and the orange coolant but that was almost a year ago and no problems since then really. But the thing with the battery gauge it seems like it leans a bit towards the left side of the middle. usually when i have the a/c on.. Battery is only about 1 yr old...

 

If I'm idling with my A/C and maybe the stereo on, it's not uncommon for my needle to go toward the left side of the voltimeter, I wouldn't be real concerned about that. The problem could be a bad thermostat, air or a blockage in one of the coolant lines.

 

You need to determine if both cooling fans are coming on high. Although I don't like to see 260 degrees you are still not overheating. Find out if both fans are running at high speed next time your temps show 240+.

Personally I would install a manual fan switch to see if you can get the temperature down manually. If you install the manual fan switch with LEDs you can see when each circuit becomes energized even if you don't have the switch on.

 

Exactly.

It is more than a dummy guage because I can tell the diff in temp on my engine between the stock t-stat and the 160*. Its desensitized to not move with every degree change but it'll work w/in a ~10* range. Thats more than enough to tell if you have a cooling prob and far from a basic dummy guage.

 

cooling fans dont do any good at speed on the highway.

IMO, you either have a stuck thermostat, or low coolant.

how does the car act in stop and go, or at low speed?

 

dude. no. it's overheating on the highway. fans don't matter at those speeds.

 

Your point is a good one but I haven't seen from this thread the speeds this is happening. We can assume he's traveling over 30 mph but I've been on the highway many times and stuck in stop and go traffic.

 

this is true. i assumed that since he said he was on the highway that he was going 55mph+. otherwise he would note that he was traveling at a lower speed.