I just noticed the other day that my temp guage is actin up. It works but it goes back and forth between about 170 and 220. It doesn't over heat or anything and drives fine, but it just goes back and forth just drivin down the road. I'm wondering if this is my temp guage goin bad or it's my actual temp thats bad? I'm dumbfounded...

If I had any doubts I'd change the sender and the thermostat!
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

I think the first most likely cause would be some corrosion on the hookup to the sender. The 2nd option would be to change the senser. The third option would be to change the thermostat.

i think thats just a jeep thing. mine does it as well. my best guess is that the stock cooling system does a good job, but the thermostat opens at 190 or so, when it cools to less it shuts and the engine starts heating again. opens and cools, shuts and heats up, etc etc etc

Gus he is talking about a 50* swing back and forth.. He should have a 195* thermostat in there and the temp should NEVER go below that when running. I have seen 220* in a wrangler before but it was under fairly hot circumstances. After reving the engine a bit the temp came back to 200* or so and all was well.
Big JIm
Ps Saturday Tony Stewart ran his race car for 40 1-1/2 mile laps at 180mph with a temp of 275* and spewing steam... Pulled something off of the radiator and the temp went back to 230* and he ran the rest of the race with no problem.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

right, mine temp gauge goes from 210 to the line on either side being about 50* of difference. i never figured it was a big deal.