Have a look at the Revotec range of electronic fan controllers from Merlin Motorsport.
They do an inline range to suit various hose diameters and they can be set to whatever temperature you choose.
The Flex A Lite controller is a bulb and a wire that goes under the hose clamp into the hose. Not good. Hard to seal. Also if You live in the UK use a UK product if at all possible.
