If the temperature gauge is only halfway, it isn't overheating. It's just running hotter than usual. I don't know why it is, but people seem terrified on the K10 running even a little bit hot.
If you are that fussed about it, check the cooling system:
- is it full with the correct water/antifreeze mixture?
- is the radiator in good condition, not blocked or falling apart?
- is the thermostat working properly?
- is the system full of crap or something (flush it)
- has your headgasket gone? (Hellman's Finest in the radiator and expansion tank would shot up).
The thermostat is on the top of the engine near to the distributor, held on with 3 bolts. Open it up, gently lever it out, stick it in a pan of water just off the boil, and it should open fully. If it doesn't get a replacement. Make sure you replace it the right way up with the check valve at the top and use some instant gasket to seal it.
The thing on the radiator with the wires is the fan switch, if the fan is coming on as the engine gets hotter, then it is working.