Could be a small hole or even be corroded. Remember it is under pressure so a very small hole will squirt out. check all rad hoses also for tightness and condition.
my radiator has plastic tanks and cracked after a lean mixture of coolant froze and expanded the plastic tanks.
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.
radiator leak. try adding " leak stop"
Where is it leaking from? Could leak from the radiator, hoses, or water pump.
blown head gasket
No. The only times the radiator would leak is if it was damaged, defective, or corroded.
Find leak, repair/replace cause.
If the radiator was not fitted in properly or the pipes were not attached correctly, the radiator would leak.
Coolant leak? Check your heater core.
Yes. It also depending on what kind of stop leak and how much is used.
There may be a hole in the radiator?
It depends on what you mean by "run out" but there is probably a leak in the tank.
yes it would, I was having the same problem. good luck!