possibly saggy hood liner, there is room to have the housing angled slightly different, maybe I have a motor mount on the way out and the motor is able to move a little more (they are still intact so still good there visually). Handful of potential variations, but if the hood is contacting the housing the short section of pipe coming off of it already I'm not too pleased with it's bend radius the slight pressure from the hood could be restricting flow. It's not collapsing the hose or anything that radical but slowing things up enough over a 30-35 min drive the temps just slowly steadily climb.

 

Interesting, I also just installed my 180F kit and have similar coolant temps; I notice you are also in a mountainous region (most of my driving is 5500 - 9000+ft Sierra-Nevadas) and perhaps the Disco2 radiator just cannot keep coolant temps in the 180-200F range with high ambient temps under consistent load. Cruising uphill on the freeway with AC at 68F and ambient at 97F at 70MPH for several minutes brings my coolant temp up to 212F (+ or - 2 degrees) and oil temp to ~240F. Once the vehicle is coasting downhill my temps drop to 190 - 201F. If I do a run in the early morning/evening when ambient temp is 78F then my temps stay between 183F - 201F. My radiator was also replaced after installing the kit as I was initially seeing temps as high as 220F. I am also running the Dorman fan, heavy duty Hayden fan clutch and Saudi grille.

 

I run a stock setup 180 on my built up d2 and don't have any major issues with it. It hasn't gone over 205F regardless of conditions. That rig sees serious idling times at elevation at high temps when on a wheeling trip with zero issues.

 

Just an update, I pulled everything apart and the rad had a small pinhole on the top of the driver side end tank that didn't drip enough to be seen with the plastic on. Replaced radiator, water pump and crank pulley and main seal and its running fantastic and temps are staying down where they should be. When diagnosing at idle it took way longer than I had given it when I made this post to see the temp increase past where it should be....but I did notice when I let it run after that that my crank pulley/harmonic balancer had a gnarly wobble and it was the source of a growing oil leak. Picked up a known non leaking used one and threw that on with a new seal. All good now and should be ready for issue free (cooling wise that is lol) daily driving duties.

 

Congrats!