Coolant temprature on 109

Rite i have fitted a 200tdi in to my 109 with the discovery radiator and have always wonderd why the temp gauage was in the red all the but the engine did not over heat. So i have fitted a temp dial gauage and no matter how far u drive the vehicle the temp stays at 66 degress and wont move. But the thermostate is a 88 degress state.
What should the temprature gauage read?

Hi, I would exepct that you still have the original temp sender on your TDi. And you have the original gauge for a 109. So there's a mismatch. Suggest you look into changing the temp sender on the engine. I don't know what fits, I'm sure someone will be along with the info.

If not, just live with it. You're obviously not overheating.

i think lodger is correct. a 200 tdi sender is not compatible with the series guage.
you need to use a series sender which can be adapted to fit the m16x1 200tdi head using a 2.5 petrol engine temp sender adapter.

hope this helps

Hi i have used a series sender still the same so taken it out and fitted a capilery gauage now

OK, a couple of quick questions/observations, then;

1 was the original series sender working? If yes, how do you know?
2 Is your fuel gauge working correctly? if problems there you may need to look at the voltage stabiliser just behind the dash.
3 If you're happy with all that, try testing the whole set-up with the sender in some hot water, make sure you earth the sender on the engine, put it onto the water, measure temp with a thermometer, check reading on your temp gauge. At least you know where the needle is on the red mark and at what temp. if you used boiling water from the kettle, then let it cool down then you would see the changes in needle positions and at what temp.