Hi!

I have a 1995 Dodge RAM 2500HD with a V-10 engine with whatever the best cooling package was at the time. For years, the temperature gauge sat around the second mark (pointing at about 10 O'clock) no matter what I was doing with the truck. It could be 110 degrees out, pulling a loaded trailer at 75MPH with the A/C on and that gauge never moved.

Recently, however, that gauge has started to move around when the truck is under load, and sometimes can get all the way to the 12:00 position or maybe a bit more. This truck only has 23,000 miles on it, and everything is original. Coolant level is correct.

I am suspecting a defective thermostat, and want to replace it. However, I can't find any information on what temperature thermostat is installed in this truck. Can someone tell me?

Also, does anyone have any idea on what this could be if it is NOT the thermostat? Since it only happens under load, I am tending to rule out things like senders and such.

Thanks!

This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235973

Remember that this only happens under a decent load. It does not happen while idling (can idle all day and not budge an inch) or under a "normal" load.

While it's possible that it's #2 (blocked passages), #3 (bad thermostat) or #7 (defective fan), I can safely rule the others out. And I'm pretty sure the fan is working correctly (it's not electric). I'd like to start with the thermostat, but I am having trouble determining which temperature part is installed in the engine. I want to have the information in hand BEFORE I remove it. If the symptom continues after replacement, then it's necessary to start thinking about other things.

I was just hoping that someone would know which part was in my engine, and if this symptom had been seen by anyone else with a specific cause. Thanks!