Technical 2.8 JTD 2003 radiator temp sensor

[blaven]

I had my radiator changed about two years ago, together with a new front cross member (it seemed to make sense since I was committed to keeping my camper van). It's a Murvi Morello 2003. Last year whilst parked up after a long run I noticed a coolant weep from under the front near side bumper. Investigation eventually showed that it was weeping from around the big 29mm. brass nut which is part of the sensor. I bought a deep socket from eBay and tightened it up and cured it.
However, the sensor is not connected to an electrical cable of any kind, and there is nothing hanging loose in the vicinity which suggests any sort of connection. This sensor then, has no function other than blocking the threaded hole in the bottom of the radiator.
I have never seen my water temp gauge deviate from the middle position no matter how hard the van is driven. I know from reading other posts here that the radiator is very capable in keeping the coolant from overheating. I did 6k. Miles in Scandinavia in June and this was some severe sustained hairpin bend climbing for miles and miles. The radiator fan only ever came on once, and that was after a lot of second gear work. So how is the fan switched?
I can only think that Murvi re routed a connection to take into account the on board water heating system (Eberspracher).
Any ideas guys?

 

[LittleGreyCat]

I assume that the temperature gauge shows the normal cold -> normal period when you first start driving. If so, it should be working fine.

With my 2002 Hymer I've never managed to get the needle half way up the gauge and I have had the cooling system checked by a garage.