TD5 questions from a LandyZ newbie

Hello! Good Evening.

Iv only just found this place after years playing with Landy's!

Anyway

Now have a TD5 with an issue; The thing won't warm up. Obviously I know it could be thermostat or maybe fan overcooling but thought Id see if any experts here can shed a light as to which is more probable? Or, if there is any other possible cause as I know very little about TD5'S.

Oh, anyone ever done the veg oil/diesel mix in a TD5? I did it in a 200tdi ok but wondered about the TD5?

Thanks
ETA to add, she's covered 117,000 with good servicing

try a new thermostat (about £18). They get weak after a while and require less pressure to open the bypass valve.