I have a '97 RAM 2500 4x4 that is fluctuating temps. When I first start it up and drive it the temp gauge goes all the way to 3/4 which I think is 220 or so and then will all of a sudden start going down to around the 190-200 mark. It will sit at 190-200 when I idle in park, but then if I give it a little gas it will start going down to about 170-180 until I let it idle again where it will start rising back up to 190-200. I don't see any visible leaks in the engine compartment nor under the truck. Any ideas what this could be? I already tried to "burp" the system. Could it be an air pocket still or possibly my thermostat sticking?

 

I think you are on the right track thinking the T-Stat is sticking. I'd flush the whole cooling system, then replace the Stat.

And welcome to DF btw. Thanks for posting in the correct section and for having an appropriate thread title.

You might also want to check your fan clutch.

 

Seems like that fixed it. The temp gauge now reads between 170-195 or so and never goes above 200 anymore. Wasn't too hard to change too. The air filter housing, however, is a little interesting to try and get back on.

Now, the only other main concern I have is the 4WD light on the dash seems to keep flickering off and on when I drive, but the truck is clearly not in 4WD (and the 4WD works when engaged with the shifter).

 

Glad the tsat fixed the temp issue.

Can't help with the 4wd, but someone will chime in.

 

Nicely done on the resolution.

I might have a suggestion about the light, but no guarantees. When you're feeling like getting down underneath the front, start on the backside of the front axle, and find the CAD housing. It will be to the right or passenger side of the pumpkin. You'll see some lines coming out of that location, vent lines and electrical. Follow the electrical line which will go up and over the front cross member and forward to a connector near the bottom of the radiator. Check it's integrity.

Then check all the other lines, which are vacuum lines and breather lines that come from the CAD.

This is some place to start.

 

I'll check the vacuum lines.

I drove the truck today and the temp still fluctuates a good amount, it's just below the 200 mark now and not over after the t-stat replacement. Now it will seem to be operating at normal temp (right below the middle 200 mark) but after I am at a stop and step on the gas to go the gauge will drop down to like 160 or so within a few seconds and then go back up to the 190-200 mark after a few more seconds. Could there be air in the system possibly?

 

There could be air in the system. When you burped it before, did you raise the front left? That usually makes it a little easier.....notice I said easier, not easy! These can be tough to get all of the air out.

 

That would be front right.

 

No, I didn't try that yet. I'll try getting the front up higher and then re-burp the system and see if that works.

 

Like HeyYou stated, front right, as in passenger side. As far as the 4x4 vac goes, check it in this manner. http://www.dodgeram.org/tech/repair/..._engagment.htm