Mine has done it today after being on the motorway for a while then getting stuck in traffic.
Do I just need to change the main front radiator? And refill with coolant as I understand the bottom part which cools the gearbox gets clogged up, and mine is right on the milage this happens at-75k.
Is changing the rad on these quite straightforward?, I would rather do it myself if I can so if anyone has any tips I would be grateful.

Very straightforward.
I'd also replace the hoses, belts and consider the water pump.

Remove the top hose.
Unplug the plugs to the sensor on the cowling, move the wiring out of the way.
Remove the fan (LH thread) & cowling.
Remove lower hose to the gearbox heat exchanger and lower hose with thermostat.
Remove the two plastic screws in the slam panel and ease it forward, pull the radiator assembly up and out.

Replacement is the reverse of removal.
Refil with the correct concentration of coolant.

As you've now overheated the oil and its done 75kmiles, seriously consider dropping the sump off the gearbox and giving it and the magnets a clean and renew the filter and oil.

Thanks, doesn't sound too bad, I will change the rad myself but think I will get the gearbox oil changed at a garage as I don't really know what I'm doing when it comes to gearboxes.

Sorry, also to add it looks like there are some A/C hoses in that area too, are they all out of the way of the rad?, I'm assuming the condenser is in the same sort of area.

Condenser is in front of the radiator but the hoses go past the side of the radiator. No need to move them, the radiator comes straight up. You need to do a slight wiggle as the lower outlet comes past the fitting but its not a problem.

Honestly, with the gearbox, if you can get safe, comfortable access to the area (pit / ramp) its straightforward and there is an excellent "how to" on the www.

hi, dont want to sound stupid but how do you know when your box is overheating... V8 facelift Range Rover Autobiography 22" wheels.
1976 Harley Davidson Iron Head Sportster

daveo wrote:

hi, dont want to sound stupid but how do you know when your box is overheating...

The gearbox goes into protection mode when it gets too hot - This mode has similar characteristics as "Sport Mode", ie, it holds onto gears for longer on the way up, and shifts down quicker. If it still can't dissipate the heat, the warning message comes up.

The amount of corrosion inhibition in the system is important as there is a lot of alloy in the system (rad etc). I replaced the old coolant with a new 50/50 mix, the new concentrate being bought from Land Rover. I'd suggest that you don't just use any old antifreeze as some of the modern versions don't mix together.

Once you've put everything back together, patiently top upthe header tank until its on the line. Give the top hose a squeeze and you'll probably see bubbles coming back through the little breather pipe from the top of the radiator into the header tank. Once correctly full, start the car, check around for leaks and monitor the level in the header tank for a couple of mins, then put the cap on and take it for a short drive - Check the heater is working and then let the car cool down again (Don't remove the cap on a hot engine). ie, overnight. Then check the level again when its cool and top up if necessary.

HTH