Replace it, should only coast a few bucks at auto parts store.
to the coolant recovery tank if so equipped - if no coolant recovery tank then not connected to anything - just an overflow
It uses the cap on the coolant recovery tank as its "radiator cap".
The overflow tank is either cracked or its overheating and leaking from the cap
When all the coolant in the radiator and coolant tank heats up the volume will increase and force it's way through the weakest point which would probbaly be the cap on the recovery tank - if you have filled the recovery tank to the maximum you had better take half of it out.
Either the cap is bad, your tank is either cracked at the seam or it has a pin hole that you can't see and the coolant is vaporizing ( steam ).
On the coolant recovery tank
I believe it is on top of the plastic coolant recovery tank - thread on cap
There isn't one, just the cap on the coolant recovery tank.
If you have a threaded cap on your coolant reservoir that is your " radiator cap "
There isn't one.The system is designed to use the recovery tank on the driver side. There is a cap on the recovery tank and you check the level there and add coolant there.
On the top or upper side of radiator or at the coolant recovery tank
With the radiator cold, remove the cap and fill to the top. Then remove the recovery tank cap and fill it halfway.