Both of those gauges are reading from the same temperature sensor. I noticed when I replaced my dead sensor with one from a different model Rover it started reading very low, so I pulled the one from my parts truck and everything went back to normal readings.

I have the Dorman/Hayden fan setup, but not the HD fan clutch. It's only loud for a short while after startup, until things come up to operating temperature. If yours stays loud, perhaps there's a problem there.

 

I was also thinking....heavier clutch, different fan, harder on the waterpump, bearings.

 

I’ve run that setup for 3+ years on 5 personal D2’s, and even a P38 I had for a short time. Zero issues with the water pumps on any of them. If it was going to kill a water pump I’d have certainly had a failure by now especially when I’ve used the 30.00 ebay wonder water pumps on a few of them or slapped em on old existing water pumps.

Also this setup does not slip when the fan clutch is fully engaged. A tell tale sign the fan clutch is to strong for the current setup = fan belt will slip when it engages. The 2991 does not do this with an OEM LR fan blade or Dorman 620-112 unit.

Since he’s already had a previous OEM setup explode maybe there is a common denominator to all this. However with a new fan clutch, new fan blade, and I’m assuming new upper shroud/lower shroud, and fan belt I don’t see how it could be any of those parts. Fan belt routing, proper fan belt length, good tensioner, good pulley bearings, or play in the water pump won’t contribute to a fan clutch staying engaged.

The 105F still seems very vague to me. With very little throttle input I could see it dropping below 188F and that would close off the thermostat, but I just don’t see 105F because if it closed back up it would build up the engine temp eventually and the thermostat would open, cool down, and repeat the cycle over & over. I just don’t see it getting down to 105F. The heater output would totally go away, and it would probably even make the ECU think it was a cold start scenario (could explain poor MPG).

I’d slide something in there to block some (not all) the air flow & “test” to see if a 25% blockage gets the temps to stay warmer.

I mean honestly I’ve driven a Jeep Wrangler in the dead of summer without a fan clutch or fan blade period..... I jumped on the road & cruised at 65MPH all the way to the auto parts store 20 miles away with the temps in the normal range because I was moving & air was flowing thru the radiator. The fan & fan clutch are for slow speed assistance to the cooling system.

 

No, I have an actual stand alone gauge and sender.

 

So, keep in mind, both the stock temp sensor (in the bottom of the radiator) and also my secondary temp sensor, are in the thermostat open (radiator side) of the cooling loop. So my current thought is that maybe the actual engine coolant temps are ok, but nothing is reading those.

 

The stock temp sensor is located in the intake manifold, the other temp sensor located on the radiator is for SAI equipped D2's.

 

Intake manifold? Like air temp?
Mine does have the SAI.
So which does the engine temp gauge get it's reading from?

And also, yes, I always use lower gears going down a large hill for engine braking.

 

The engine temp should come from the intake manifold sensor. The other sensor is part of the SAI & it’s more for emission/SAI readings.

 

Here we are, 30 minutes in to our drive on a 15 degree day in the Colorado mountains. It got up to 150 Max. And, again, my aftermarket gauge has its own sender. Yes I'm geared down when possible, but that just spins Elsa's ice fan even faster, so that's diminishing returns.
The check engine is an intermittent O2 sensor code.

 

Thermo is stuck open