Radiator fan could be bad, fan relay bad, fuse blown. Also if your ECT (engine coolant temperature) sensor is bad the ECM (computer) won't know to tell the fan to turn on.
I'm pretty sure the fuseable link is underneath the battery...
Bad water pump, stuck thermostat, clogged radiator, blown head gasket, trapped air in cooling system, defective cooling fan, defective thermal relay, or a combination of these.
a bad fan control relay
Several solutions: Change the thermostat (could be sticking shut).....backflush your radiator....could be dirty and clogged, replace radiator hoses, check for pin hole leaks in your radiator. Is the fluid level staying normal or are you constantly adding anti-freeze? Halfway on the scale is normal.
I would use a good epoxy.
Radiator cap
Are you overheating? If so,you may have a radiator that is plugged and needs replaced. It may just be too old and is leaking still needing replaced.Third,if you have a head gasket blown,it can push the coolant out of the system.You would have to check the compression to find this problem,not a hard one to diagnose either.
A radiator cap would not cause a leak! However, if the radiator cap is holding pressure, other weak parts could signal issues in need of attention.
I would suspect a clog in the radiator.
Depending on quality of radiator and charge per hour, I would say $200 at least.
radiator cap
no one cares about it, just forget it iof it's about homework