Overheating JK CRD 2.8L Manual

[Yt2]

Living in the Pilbara, hot is the name of the game. Using the torque app, I have found the following.

Medium size driving lights add a couple of degrees, see CRD Spotlights and Heat post.

Opening the numberplate flap on ARB bar decreases temps by 2 degrees (no winch installed yet).

I drove to Broome the other day temp was 42c. Sitting on 110km/h on a flat road temp gauge was slightly over half and not in the normal position. Turned on Torque, lifted number plate and watched Torque. Water was 106 oil 115 with spotties on the bar. Temps came down by a couple of degrees due to flap lift. An hour up the road, I noticed out of the blue water temps dropped to 95c for 40 seconds then went back to 102. I noticed this cycle happen about 4 times then stayed around the 102c for the rest of the trip. I have seen this happen now on 3 different occasions.
It appears that the radiator can cope, but either the thermostat or fan is not operating correctly. On the Broome trip I was 2 hours into the trip when something good happened. Why would it take so long to work, then only work a few times?
Yt2...

[jeep112]

102 degrees is in normal working range id be happy with that in 42 deg

[MidnightMods]

The thermostat starts to wakeup at 74deg, so at 100deg you are fairly high % range past open, while the system is pressured at 22psi, the boiling point is much higher, but long term high temps and Mopar coolant lead to shitty cooling systems and bottles splittings causing engine failure.
102 at 42deg is very good still in a Jk!

[MRGC]

Just came back to Sydney from a trip to Hervey towing a 2t boat, on the way up some hills caused the temp to go just over half, coming back to Sydney on some hills the temp got to 3/4 and climbing.

2 questions how do I check my viscous fan if it's on it's way out and any mods I can do to help keep the temp down when towing eg: lower temp thermostat?

[wranglertj]

yeah I had similar issues with my 3.8l petrol going from Adelaide to Robe just recently as was 40 degrees, towing and on hills temp would go as high 3/4 without aircon on and only worse if I switched it on. I am going to change factory radiator to a larger 3 or 4 core depending what will fit.dont buy the cheap Chinese aluminium ones as they don't last as I have seen on a number of occasions in mates forbies.

[MRGC]

Thought I'll add crd auto.
I don't have the room to go larger radiator, I noticed people are talking about mopar coolant, is it better than the red long life coolant?
Is mopar coolant clear in colour?


, [____],
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[wranglertj]

when I say go larger (not sure about the CRD engine bay) but on the petrol you can go 'fatter' ie more cores not wider which will better aid in cooling.