Why a little hole designed on the engine casting cover n now water is leaking?

Hi, thanks for reply buddy, you are correct the leaking hole was right behind AC compressor. I took off the AC compressor and found it as coolant water was leaking behind it. do u mean this hole is for the water pump to flush the coolant or was its designed for temperature indication? Can i block the hole with anything without changing Timing Belt?

It's more designed to leak when the pump needs to be replaced, as a kind of warning. If it's leaking it needs to be replaced, so blocking it isn't the best idea. Replacing the water pump requires removing the timing belt anyways, so it's only a little more in parts to get it all done.

Alright thanks for the useful information, buddy.