I have a Vauxhall Vectra switch fitted to the rad on my Indy Fireblade. Before fitting I heated the switch in water, it started the fan a few seconds after the water boiled. Assuming thats a 100 degrees do you guys think thats a bit high or will be ok when the system is pressurised ?. Do you all have your sensors in the rad or do some of you have it closer to the engine in the top hose?.

don't the vauxhall ones usually have the temp range stamped on them?

Couldn't see one

pressurised system should ensure it kicks in prior to 100 I believe, remember the fan is for static not when moving, if the fan kicks in while moving there is generally a problem with the cooling system

I've just done the easytherm measurements on my temp sensors, i assumed that water boiled at 100DegC, it turned out to be 86Deg, The water vapourised/turned to steam at 100Deg.

Won't help with your question, but should give you a better idea of when things were happening.

ATB Dan.