Hi guys. I just recently bought a used 2003 Montero about 4 days ago. Just yesterday when I was driving it, I noticed that my temp gauge would just climb straight to the H. But I know that the engine wasn't even warm yet at that point. I pulled over anyways and checked under the hood and there were no signs of over heating. The engine was even cool enough to touch. My coolant is topped, no signs of leak, no signs of coolant in the oil. I even took the chance of driving it for about 25 min. The temp gauge during that time would go straight to the H and would dip down from time to time, but no overheating. If anyone could suggest or try to point me in the right decision it would really help!
Thanks in advance!

 

This is a known issue in Monteros. Very annoying and scary when it happens. You can search the forum for known fix. Start here to get some ideas:
https://mitsubishiforum.com/forum/mi...p-gauge-47609/