P38 overheat!

Hi friends!!
New here!....and need to comment My problem (hope my english is not too bad...I´m from Canary Islands,Spain).
Recently have a RR p38 2.5 DSE.........I had the gear box new from ashcroft...goes well.......had a new radiator, new hoses,new water pump and nes thermostat...new everything.....the engine goes perfect in sound,no smoke,no deposits in the oil engine lid, etc........
Filled the sistem with coolant water and gave if a drive......it goes hot.......just up to one oclock...(the needle normaly sits at 12 on mine....here is pretty hot normaly).....to the white line...doesnt go to red. When the car is parked with engine on......temperature is ok. When you drive in horizontal the temperature doesnt move...when you go down hill it goes a bit down.....but when you go uphill it goes up.....not to the red as I said.
¿Could it be air in the system?.......Could it be the head gasket?...Dont know what to think!?
Hope you can help!
Thanks!

Going uphill with the aircon on towing the caravan in 30C mine goes to about 1 oclock. Turning the aircon off drops the temperature pretty quick.
Could be you have air in the system as you have refilled it.

HI!
This morning turned the car on....let it warm up with the expanshion tank cap off untill it warmed up.......no bubbles coming out of the system......and the water flowing well Ithinks!........But I dont tow anything....it souldnt warm up to about 1 o´clock y the temp gauge I sholud think!

Hope is not the gasket!!

Hi!!!
Today I didi what you said.......started the car,ran it....it got hot........when that happend I turn the engine off....then on...the neddle on the temp gauge went up to the same position.........te gauge must be right!?
What I find is that untill the temperature doesnt go up to about 1 oclock.....the viscous fan doesnt start to spin hard.....and sometimes you dont hear it much at all.......¿is the fan caput?
The temperature sensor must be right because it moves quite well up and down.....?
So....resume....it keeps overheating......but no watter in oil....oil in water...nothing!???
Cant figure out what can be.....but sure goes hot!!
Any ideas?
Thanks all!