About a month ago I noticed that water in the expansion bottle seemed to dry up everyday i.e the level goes below 'min' daily. This did not affect the engine temp as I had rigged the fan to run on high at all times.

The problem started when I reverted to using the rad switch. when the car is idling, the Fan does not spin (not even low) but when the temp reachs 80C i.e somewhere between 70 and 110 on my temp guage, the fan starts and spins on high speed and then turn off when the temp reachs say 75. When I stop and check the expansion tank I find that water is boiling over.

Can anyone tell me what is going on? Thanks in advance.

Is it just water or an antifreeze mix? It sounds like the fan/switch is okay, perhaps a ciculation problem like thermostat or clogged radiator.

Its water and rad coolant. I had to have the thermostat removed for proper circulation otherwise the car would never have made it this far.

I will change the single cell radiator currently in it to a double cell radiator and see how it goes.
Thanks.