I just finished head gaskets and put every]thing back together. Had replaced the water pump, thermoswitch for fans, timing belt. Should the fans be on at idle or during drive or both? My coolant started boiling out when I had pulled into my driveway after a mile drive. Fans switch on for like 10 seconds at a time but dont stay on, come back on every] 5 minutes or so. Please help got to drive up to school tonight or early] morning.

 

When the coolant's temperature has hit a pre-determined temperature, the fans should come on anytime during idle and continue to be on until it has cooled down to a set temp. maybe your thermoswitch is defective.

 

That would be my first thought too except it is brand new, just replaced. I thought that was the cause of my overheat a few months back which led to me doing head gaskets and all that other work recently. I just did a drive for a couple miles with my] switch shorted so the fans were on the whole time. Let it sit after with fans on and no boil this time. So its def the fans that are causing the boiling. So with a new thermoswitch, assuming it is good, why else would the fans not be coming on?

 

Do the fans come on when you have the AC on?

 

Have you also replaced the thermostat?
If not then it is possible that your engine is only using the coolant in the engine block and not what is in the radiator because the thermostat is stuck shut. JM2CW