Hey guys thanks for your replies, they are all very much appreciated.

Following conversation with my engineer (and his insistance that he has eliminated the loom already), this morning we have rigged an independent set up to test the guage and the sender. We still don't know which component is incorrect but at 65 degrees C, the guage reads 7/8 toward the red and at 83 degrees reads well into the red. I understand the thermostat operates at 82 degrees.

In the UK the main Hyster dealer has been replaced by Briggs Equipment in the last two or so months and the organisation is currently in total dissaray (they don't even answer their phones anymore).

UK customers had for some time been directed by the former Hyster agent Barloworld to use TVH (formerly Intrupa in the USA). As you can imagine it was TVH who supplied the (well said swoop) "crappy" parts.

So back to my original question, does anyone know the resistance readings we should be getting through the sender....