Coolant leak

[dsmusicmaster]

After the car is off overnight for lets say 8 hours I found antifreeze leak on a small flat metal part behind engine. Can somebody tell where it comes from? pictures attached
After driving I have to wait those hours for that leak to appear there. no overheating though.

[Trevor]

I would be tempted to add some StopLeak into the cooling system to slow down or even stop the leak as sometimes it can just be a porous casting and the StopLeak just blocks the hole enough to not require replacement of expensive components.

[dsmusicmaster]

that is also solution, thanks. I just wanted to know if somebody knows or experienced that and can tell if coolant that appears on that spot on photos if it can be from water pump or intake manifold, head gasket or...???