If you decide to use an electric pump you can take the impeller off the pump shaft and just use the pump as an idler for the fan belt.

Whatever real cooling problems you might have - you DO have a problem with the gauge. There's no way on this planet that the engine is getting that hot that quickly. It wouldn't overheat that quickly if you simply connected the rad hoses together.

Are the gauge and sender a matched pair?

Have you tried an independant method of verifying the temperature?

Are you seeing any other signs of overheating beyond what the temp gauge is telling you?

Iain

I've never had cooling problems - the Allegro rad even deals with the Toyota lump without problem.

One thing that occurs to me is the size of your front to rear pipes - they shouldn't be any bigger than about 30mm dia to keep speed of flow up.

My experience with the electric pumps is that they spin far to fast for the small mini engine, the majority were designed around large V8 engines and predominatly race applications. If you run one without any changes in speed the pump will circulate the water quicker than the rad can cool it. As for that I did have one in my mini race car but I ran this through a large resistor and dropped the voltage to 5v this was plenty for the mini. I have no problems in my setup and I'm running a very healthy 1430 unit in it, as the others said I would say its something more simple than mechanical inefficiencies. If you have no bleed screw use the heater take off on the head to relieve air, mine is brutal to bleed and I end up having to fill via the heater take off to prevent airlocks and make sure the system is purged. Mine can now sit all day in traffic with one 10" fan and at 80 degC. Can you get hold of a temperature gun (laser/infrared) if you can use this to determine temperature.

I ran the smaller Davies Craig water pump in mine (not the very small heater pipe sized unit) alongside the standard water pump. It was controlled on a thermostatic switch and it worked really well.

I was also able to use and oil/water laminar oil cooler which dumps the excess oil heat into the water system and it still ran at the correct temperature.