I have a V reg Fourtrak TDS (72000 miles). I thought the temp guage had gone last week as it stayed down at the cold end. But then we quickly noticed we had no heater either. Turns out the fan is turning full time and over-cooling everything.
Local garage had a look at it but can't fix it. Fan turns freely by hand but there is just enough (viscous??) resistance for it to start turning whenever the engine switches on. What is the remedy - replace fan ??