Pajero Owners Club of South Africa

I recently had a major failure on my 3.5 V6 to the extend that I had to replace the engine with an import. I fitted the new engine after replacing the cambelt, thermostat and radiator cap. It started 1st time, and is running incredibly smooth, not even a lifter noise.
When I took it for a drive this weekend I noticed that it got a bit hot (3/4 of gauge) when under load, and I sure do not want to replace another engine soon. Can anyone tell me if this could be due to the thermostat's jiggle valve not being in the correct (top) position?
The radiator, hoses and fan seems fine and the water level in the radiator stays constant. I also verified that the thermostat opens.

Hi. Temp sender unit might need replacing if it came off an import motor

have the radiator flushed, pressure tested and cleaned of debris between the heat fins.

Thanks for the quick response guys. I will start with the radiator maintenance (flush, clean, pressure test), it is anyway a good thing to do on a 11 year old cooling system. I can then also ask radiator shop to properly fit the thermostat, because it will be way easier to refit when the radiator is out. If that gives me no joy I will have a look at the temp sender unit.