Hope I can help with this!
I currently have a Mrk 3 GL 1.8 and the temperature gauge goes to about 100 degrees on the gauge before the fan comes. With a diesel, it will take longer to reach its operating temperature but it should still get to 90 on the gauge after driving for about twenty minutes, depending on the outside temp of course!
However, the gauges on the Mrk 3's are prone to over and under reading after a while. I would not worry to much about the reading, just check your coolant regularly and make sure you do not have any coolant loss. Otherwise, if it really bothers you, you may have to replace the dash panel insert which can be a costly part!
Let me know if you have any further problems!
P.S. Also from the UK, enjoying the snow!
Friday, January 8th, 2010 AT 4:17 AM