Hello Bob,
Thanks for taking the time to give such a comprehensive reply and it does explain why the temperature varies with speed if the reading is coming from the head. I still can't make out exactly what's going on but it seems the better I get the air flow the higher the indicated temperature for any given speed so whereas it would sit at about 98 at 50 - 60, 100 at 70 and 102 ish at 80 (not that I ever do 80 you understand) with the fan cycling on and off it is now reading about 100 even at 50 and 102 at 70 but I can't hear if the fan is coming on or not. I THINK the fan must be activated by a different temperature sensor because it comes on at about 100 when idling in traffic and stops again quite quickly even though there is little change to the temperature readout. It does not run when on the move at 100, more like about 102 or 3.
I am wondering if the water is now cooled further returning to the engine and whatever sensor works the fan is remaining happy although the readout from the head is higher, is this caused by the thermostat being closed further due to the cooler water entering - who knows! It would seem I may have wasted my time but the point of all this is that the fan relay failed once when queuing for the Eurostar which resulted in boiling water and steam being ejected all over the passenger side windscreen. If this happened at speed heaven knows what would be the result but I'd rather like to avoid the need for the fan anyway!
I think I'll leave it for a while and see what happens when the ambient temperature is higher.
Strange yours is steady at 90 - 95 assuming the set up is the same as mine.
The thermostat I fitted came from Melvyn and was the same rating as the one removed which I think was something like 98 - 102
Again, thanks for your response, it's very interesting to compare.
Regards
Simon
