[Synchro909]

I have had trouble with overheating but I can't get angry with the car.
On an outback trip, I was running 5.25X21 tyres with a 26% Mitchell O/D while towing about a one tonne (2,200 lbs) trailer in mid 30Cs ambient temperatures at a steady 80 kph (50mph). 3.78 differential ratio. Gradually, the temperature rose too far and it boiled. By disengaging the O/D and dropping about 10 mph, the temp came down. I have since taken to using 16" wheels which are slightly smaller than the 5.25s. That means the engine has a few more revs and less lugging. It just holds about 190-200 F under those circumstances now.
BTW, with those 21" tyres and no trailer, I can travel all day at 100kph (62mph) with no overheating problems whatsoever. The effective drive ratio with this setup is 2.86:1. The motor is just ticking along at 50mph. (not a standard engine)