But if it's fine in town and only heats up when driving fast on the highway with the air-con on, you may want to research this behaviour some more...
I also drive a TD42 engine Patrol and mine heats up so that the needle moves just shy of the red line. This only happens when I nail it in summer time against a l-o-o-o-n-g uphill (we're talking a few kilometers). When the radiator temps reach 107 deg C the air-con cuts out (courtesy of a switch at the left bottom of the radiator). Because the air flowing through the radiator is now much cooler, the temperature remains there until I slow down or crest the hill. If that switch of yours is disconnected, the air-con will remain on and the engine will overheat. Nissan calls this heating up normal behaviour because the gauge does not enter the red (overheating) zone.
I've recently had my radiator re-conditioned (no change), the vehicle does not have a blown head gasket (there's no coolant loss whatsoever) and is running at low EGTs (no more than 530 deg. C pre-turbo). I'm trying my best to make peace with it!
If you want to read many, many, many threads about this, I suggest you search through the Patrol4x4.com forum. As a matter of fact, they're discussing it at this very moment...
