overheating

Mark,
Suggest to start by checking the viscous fluid in your fan.....that's what it usually comes down to. There's been a lot written about this is the past; I had same issue with my Patrol and even now it still gets a bit too warm. My next step is a new PWR radiator ($1100-....ouch)

Same as with my Surf, the auto gearbox oil cooler is situated in the bottom of your radiator, th gear box is probally getting mighty hot, then causing the radiator to not work very well. The viscous an fluid will deffinatally help, but you will need to probally look at the top tank of your radiator as it will most likley have some little white or red or green dots showing pin hole leaks. These won't effect it much until it really starts to work and the pressure starts to build up, the leaks will drop the pressure and cause the water/coolant to boil. Also, becaus the gear box torque convertor is producing most of the heat while towing up hill, use the ATP button and select power mode. It won't give you anymore power but it will drop down gears quicker and hold on longer so the torque converter is working less, also turn your overdrive off when towing a trailer up hill.

G'day Mark L
My old Troopy HJ75 series had similar problem.
It only happened under severe load uphill the temp gauge would 'spike'
up to the red.
Reco the radiator, replaced the thermostat and coolant and flushed the block
and checked the viscous fan, all needed to be done but didn't solve it.
Then I replaced the radiator hoses - fixed problem.
I didn't prove it but I think the bottom radiator hose was collapsing when doing
some revs (2000 rpm) and then I woud floor it to overtake or similar as soon as
I lifted off the accelerator the gauge would immediately drop to normal.
It is acceptable for the gauge to read a little higher when then engine is loaded
but it should not get to the RED without there being a problem.

Hope this helps,
Moz