Over heating

Capital.

Have had the same problem with a mazda diesel, and landrover defender. Can be a number of things, in my case with the mazda it was the water pump cavitating and creating air pockets in the system, the defender was much the same, getting air in the system thru a bad gasket in the water pump area. could well be the thermostat, go for the easiest thing first .Best of luck ,

Cheers Axle.

Sounds very much like viscous fan. If so, it can be re greased easily and cheaply.
Having said that, there are many parts to your cooling system, and each need to be in good shape.

From memory, the Gregory's manual indicates to check the following things in the following order
1. Thermostat
2. Radiator
3. Fan hub

I had overheating problem in my 92 1hz recently, and by the time i'd replaced the fan hub ($100 part + fitting), had the radiator checked over ($30), and then finally got thermostat checked, and you guessed it - it was the thermostat. Cost $39 replacement for genuine part + fitting. Now the temp hardly moves.

Good luck.

Met a fella on the track who'd had an overheating problem in his Land Rover. He put in a new thermostat, replaced hoses, had the radiator re-conditioned, replaced water pump. And it still over heated. So figured it had to be a cracked head, did the job himself. It still overheated. Finally took it to a radiator shop ..the bloke tested the system and said straight off, "You need a new radiator cap mate. I've got one here, $25."
Fixed it.

Common fault with your model, get a new fan coupling or put more oil in it..however...one must ask the question...where did the old oil go...and when you answer this, you realise the seals are gone and you need a new hub.
To prove it, install an electric fan up front and turn it on when going up hill...watch temperature decrease and air cond get colder...fix fan and leave electric fan there for the aircond...this is exactly what we did to a friends 1991 1hz 80 std van.
Andrew