So my 110 300 tdi with autobox has started playing up. For years its been on the middle line of the temp gauge when warmed up. For the last two weeks or so its barely got above the quarter mark after a run. Blower is blowing heat but feels not as hot as before. Put in new thermostat and filled with new anti freeze in the correct order but no change. Top hose is warm but not boiling and radiator is all cold. New water pump about 4 months ago as last one's bearing went. New radiator a couple of years ago as well. Now its either a blockage, new water pump has sheared internally so pump isn't spinning or its way too cold and viscous fan is bust on all the time. Any ideas? Ta.