This is a strange one but am having the same thing in my intrepid. Durango--180K miles on it and never an issue.

The problem is this, the temperature will go right to the edge of HOT when it is idling for sure then cool off when going down the road. Sometimes it will go all the way to the edge of HOT even when going down the road and then will drop immediately to normal again.

I added anti-freeze to bring it to full and it would still do it. Anybody have any thoughts? Any chance that could be a thermostat? I've always thought they were either stuck or not stuck.

The other odd thing on both the intrepid and the dakota is this, they constantly are losing coolant but it is absolutely NOT leaking any place that I can see. On the intrepid, one garage told me it was NO DOUBT a cracked head or blown head gasket.

Anybody else have these issues.

The dakota is one of my son's all time favorite vehicles and he wants to keep it forever but before we spend a bunch of money painting it and fixing it up I want to be sure I can mechanically make it reliable.

Thanks everyone.

 

hmm... considering thermostats are only about 10 bucks, if it were me, I'd replace that and see what happens. You may even want to go to a lower temp. In the dak it think stock is about 190. Mine is either 180 or 185, and mine has never reached hot. In fact it never goes above half... ever. I would also wonder though, if the combination of disappearing coolant and the temp gauge issue could be a result of a cracked head/gasket leak. I'm not quite sure how you would go about checking for that, other than say a visual, or an engine tear-down.

Maybe if you checked the compression you might find a crack/leak somewhere in the head or the gasket. I would bet if one or two cylinders are significantly lower than the others that might be a problem area.

 

The factory thermostat is 195. I have a 180 in my truck and it never goes past the low mark. If your truck cools back down after it starts moving, then you don't have a coolant flow problem, so I doubt its the thermostat... but like said above, they're cheap so it wouldn't hurt to put a new one in. It sounds like the problem is you can't get air to move over the radiator at idle. If you still have the factory mechanical fan, I would suggest either checking the clutch to make sure the fan is engaging, or take the mechanical fan off completely and put in an electric fan (they free up a bunch of power). As for a blown head gasket or cracked block, see if you can smell antifreeze in the exhaust or next oil change you do, check the oil for antifreeze.