I have a problem with my 2003 Ducato 11 2.0 JTD. On normal roads and around town and on tick-over (I could leave it ticking over for an hour) the temperature gauge remains at normal (half way between Hot and Cold) however, on motorways and dual carriageways, when going up even a slight incline the gauge starts to rise and and continues into the red. The only way to bring the gauge down is to drop a gear and increase the revs! Then the gauge slowly returns to normal.

I once (inadvertently) allowed the gauge to go into the red and when I noticed I changed down and the gauge immediately dropped back to just above normal and the slowly back to normal.

Surely this cannot be right. If it is overheating it would do it all the time. Both fans run and I have removed the thermostat to aid cooling, the radiator is cool to the touch and the coolant level is spot on.

Really need some help on this......... thanks

Either the water pump impellor has dropped off, or the radiator is blocked.
I had a 97 1.9td that did the same, admittedly the radiator got hot some of the time, I changed the water pump, then the thermostat, eventually changing the radiator cured it.

Removing the water thermostat is not a good idea on any engine. When open the thermostat has quite a small hole to let water flow through, but removed it can let the water flow at a much higher rate, therefore cooling the cylinders at one end much more than the other. Depending on where the temperature sender is this could give some erratic readings on the gauge.