Mitsubishi: mitsubishi canter overheating, mitsubishi canter, temp guage

Question
i have a 1992 canter 3.3 turbo diesel. i have put in a fully reconditioned long motor, as the first one overheated and had the same symptems. The turbo, injectors and radiator were all reconditioned. The canter has a motorhome on the back and it catches a lot of wind. I live in Australia and drive in hot and cold climates. The symtems are at standard the temp guage is strait up and down (half temp)this will hold at around 80km. When pushed in hot weather this will rise right up to the edge of the red and i have to back off 60km. Then it will drop back to between half and red within 2 minuits or faster. the temp seems to rise under load but for eg will drop back a little if reved hard up a long hill. Since the new motor fitting i have replaced the radiator cap, viscos hub, exhaust manifold (cracked) and had the radiator cleaned (nothing clogging). The shroud fits well and has been checked by a few (experts). I have also fitted a snorcle for clean air. Nothing has changed the symtems. The watter pump has not been replaced. Any help would be great as this has been a long and expensive chase with no luck.  

Answer
G'day mate,

I love you folks from downunder. Your welcome at my place anytime. In the mean time, I had this with a big Ford cargo van, this thing would run in the cool range at idle forever. As soon as you took it up on the highway the GAUGE would read smoking hot. Pull it into the shop and you could touch the radiator and not get burned. Bad temp sender. There were three on this guy. The third one we replaced got it. This sounds like this is the issue. You have nothing left to replace, less the water pump. These will wear the fins off the pump stator and slow the flow down. Worth looking at. Can also cause it to aureate making an air bubble in the pump. Check the fan clutch also. Make sure it is free spinning, but turn off the engine first. ;) If it is jammed up then it will cause extra load on the engine. They don't sell this vehicle here in the States, so I am giving you my best guesses from past experience. I don't have a way of looking up any recalls or TSBs on it. Hope this helps give you a couple things to look at. Give my regards to Olivia and Mel!