I drive a 94 honda civic dohc vtec, I start my car when it is cold and it is grand till it go's up to half way, it stays on half way when I drive it at around 30mph but when it is idle for 5-10mins it starts going up near the red but then the fan kicks in for about 15-20 seconds and brings it back down slowly to half way again. Shouldn't the fan kick in when its at half way?:confused: or if its going up and I start driving again it go's back down to half way and stays when I'm driving and waits until I stop again.
I have changed the relay switch, the water pump and timing belt and the fan sensor, and bleed the system,
I don't think its leaking because I'm not missing any coolant, and the oil is OK :(
Please let me know if you have any advice

Thank you,

The radiator may need replacing, due to corrosion or mineral build-up. Only use a 50/50 mixture of recommended antifreeze and distilled water--tap water has too much minerals in it.

Thanks for your help,

I changed the radiator only last month with a new 1 and put in a new thermostat,
Still the same, the fan works fine but kicks in when the gauge is three quarters of the way up,

Any ides or advice any 1 please?

Thanks.