I am fitting a electric water water pump to a Hayabusa and want it to switch on when the engine gets up to temp and carry on pumping when the engine is switched off until its down to temp.

I need to keep the std temp sensor for the dash gauge so I need to fit another sensor of the off/on type. But where do I fit this switch so that it reads the actual engine temp? I have seen these temp sensors that fit in the hose but I don't think they will give the correct reading if the pumps not running.

Any ideas?
Jason

Any chance of getting an adapter to go in the existing Temp Sencor hole that would split it into 2, or where an engine ECU sencor goes?
They must be the best places for them as that where the Manufacturer puts them.

They would probably measure residual heat as well then, its not uncommon for our cooling fan to come on after we've stopped as when the water stops flowing the temp builds up and triggers the fan switch, that was when it was in the end of the thermostat housing (Pinto)

General consensus is that the pump should run all the time. Run it at low speed (via a ballast resistor to drop the voltage) when the engine is cold, and then switch the ballast resistor out of circuit once it gets warm.

That way there's always water flowing out of the head and over the temp sensor so you know you're not getting hot pockets in the head.

I disagree - the pump should not run all the time or it will extend the warm up time. The Davies Craig controller 'pulses' water around the system until everything is up to temperature and then controls the speed according to the sensor reading. This prevents any hot (or cold) spots and keeps everything very even. The sensor needs to go as deep inside the block as possible or at least on the same rail as the other water temp sender unit.

You can also wire the controller to keep the pump circulating after the ignition is switched off, until a specified temp is reached at which point it will switch off.