I had this on my holidays too a few weeks back Saint. Diagnosed weak viscous as it wasn't kicking in at all despite way overheat (115deg). Any how after loosing the car for a couple of days whilst the garage sourced and fitted a new viscous, it was back with me and overheating again within 5 miles. Much head scratching and a feel of the bottom of the rad revealed it was stone cold. Both electronic and mechanical side of the thermostat had given up. Ironic as Id replaced both it and the pump the month before so I didn't have any issues on holiday ! Luckily the garage that did the work on the fan helped me out by popping the innards out of the stat for the price of a good beer and I was on my way again. Back at home I tested the stat on the bench and almost had it red hot before it opened, it was well and truly fecked.
May be worth noting anyone finding this thread that these engines run hot at 105 deg so any weakness in the cooling system shows up quickly.
After fitting a new stat I monitored the temp real close for a few day - running about 104 to 107 deg with mixed driving is normal which ties in with the 105 deg stats.
