Unreasonable Water Tamperature Level

This afternoon drove my Blue Hippo and back from KL, there is a bad traffic jam along the way back. While idling, I noticed the MFD showing the water temperature is reach an unreasonable level at 103C and slowly increase by 1C after a minute. Since there is no place for me to stop the car thus I forced to drive it back as soon as possible. After go through the traffic jam area, I noticed the water temperature begin to drop(quite fast) and again it increase every time I stop when red light. That is not a good sign so I straight head up to Formula D to solve this problem before is too late.

After arrived there, I told the whole story to Adil, and he suggest me service the radiator since its a cheapest way and see whether if the problem can be solved. Its take about 1 hour plus to flush out the radiator and check whether any hose leaking, at the same time refill with the water coolant(Motul Mocool). After jobs done and start up the engine, the temperature is greatly lower than before, I thought the problem is solved but...

2 months no see, Adil had changed the carbon bonnet and side mirror.

My car is waiting for radiator service.

MoCool is used for this time.

While on the way back, the water temperature up to 85C, its normal BUT when idling, its keep increase. I even tried to start engine and idle it at my car porch, the water temperature slowly rise up from 89C to 101C(A/C on; but it will reduce when A/C off) and I bet the temperature will continue to increase if I not shut down the car. Too bad this weekend my schedule is not allowed me to visit Formula D and have to wait until next week. Anyway, could it be thermostat? A/C fan? water pump or radiator cap problem??

*All pictures above is by iPhone, sorry for bad quality...