Geez I hit 207F on the darn freeway at 80MPH yesterday. Gotta LOVE South East Texas Summers.... NOT

My cooling systems on all my D2's is top notch (with 180F thermostats), but a front skid & winch do block some air flow on the Kalahari. 210F is the highest I'll let em go. Darn ambient temps and 100% humidity suck.

 

I'm in the same boat. I am a little surprised that mine likes to stay around 200 at highway speeds when it's 85+ ambient and high humidity. Will run 187 all day long on the highway with ambient Temps under 80.

 

Personally Im pleased to see 200ish on the highway. It's well within the safe range and should be more efficient for the long hauls.

 

I've never had to be in 2nd gear at 60 unless I were towing. She does just fine in third.

 

Then I don't think we are talking about the same kind of hill.

 

Yep I have 4 D2's at my disposal right now plus my 98 D1. All of them will do 188F-193F "IF" you stay at 65MPH or less. Anything past that and the temps will climb, and climb, and climb until they max out around 206-207F. I even had my 98 D1 spike up to 212F sitting at a Mcd's drive thru, but as soon as I moved it quickly went back down to 200F within 1/4 of a mile.

From what I can tell with all my test mules is that once you reach higher speeds and higher RPM's the radiator basically maxes out it's ability to cool it down due to amount of air being pushed thru the radiator. Once you reach the tipping point then the cooling system can no longer keep up with the heat being produced at the higher RPM/Speed. Slow back down to 65MPH and over say a 5 mile stretch the temps will go down to the 200F range. Increase your speed and it goes back up, so my testing, research for my area on a wide range of LR's with good cooling systems prove that temps over 200F are in fact normal. It just really depends on your location the speed you are driving, ambient temps, and the humidity.

I even tried a 195F thermostat and I proved that on a good condition cooling system the 195 thermostat will actually have a smaller temp range vs the 180F, but overall temps are like 5F higher. The 180F will start off cooler, but once that threshold is passed up it'll climb to within 5F of the 195F thermostat.

The end result is our radiator openings are small, and the heat output under the hood is high which results in that threshold being reached at 65MPH in SETX with 100% humidity and an ambient temp of say 90-105F easy.

I've tried 50/50 mixtures of coolant, 60/40 mix, 100% water, and I even tried the Hyper-Lube water wetter stuff. The only thing not changing is my environment lol. I have tried all different fan clutches, and fan blades as well. The 620-112 Dorman Fan Blade off of a Ford Ranger is a perfect replacement, but it does not effect the cooling in a plus or minus fashion. It's just a great part to use vs forking out 3 times the $$ for the OEM unit. There is a 10 and 11 blade option for the Ford Ranger vs the 9 Blade Dorman, but I already did test on 9 vs say 11 blade fans and they result in a dead heat honestly due to less drag on the 9 blade (spins faster) vs the 11 blade with more drag (spins slower). Those results are using the same fan clutch between the two.

Then there is the Efan business. I myself went that route on an H3 Alpha with almost disastrous results!!!!! The E-Fan I was using was a 3K Spal unit which was wired and programmed to run 100% off the PCM on the H3. The electronic side of it being activated with the A/C or when temps got over 193F was flawless. The issue was the fan itself. It was fine in traffic, and slow speeds, but anything over 55MPH = 205, 210, 215, 220, 225, 230, 235, and finally I called it quits at 237F (while inroute to my brothers wedding 5Hr away). I looked for a larger fan with more RPM's but I couldn't find anything that fit the application I needed.

What I ended up doing was basically going with a D2 configuration. Fan Clutch/Fan Blade (used a Ford Explorer 9 Blade metal fan as it used the same fan clutch as the V8 in my H3), and I kept the electrical connections and installed a fan in front of the condenser just like a LR. That gave me the best results vs the 500.00 POS that nearly cost me a perfectly good 5.3L V8.

I am on top of all my LR's and I do pre-flight checks on all of them. If I didn't have so many LR's to compare side by side I wouldn't be so sure of my results.

 

My disco behaves very similarly, ide say identically except that my e-fan will keep it very cool at idle if left to sit long enough. With a mechanical fan I did exactly what yours does.

 

Yep at idle the 100% E-Fan for the engine will win because it will be spinning at a much faster rate vs the 1K RPM controlled mechanical Fan Clutch/Fan Blade.

 

2 miles or so of 30-35% grade.

Same deal around 65-75mph. I've never had a cooling issue at higher speeds.

 

I don't understand the problem.

I don't see why hitting 198° while climbing Vail Pass is a problem. (And I speak from some experience. I've never driven Vail Pass in my Rover but I've driven it in rental car many times. My brother lives in Vail.) Vail Pass is not just "a hill." It's a long, steady climb to 10,662 ft.

But back to my point - why is hitting 198° climbing Vail Pass a problem? And why do you think your fan is FUBAR?