Hi, I hope someone can help with this question. I have an off-roader running a Datsun 1200 engine with a Atsugi 56 water pump. My question is, is it normal for the pump to leak from the 4mm hole behind the pulley? If not can the hole be filled? Cheers.

No, not normal, it means your pump seal is leaking, time to get another one.

there are plenty of them on Ebay...

Is it a new pump? Those type of holes are there to let a dribble out of as an indicator of bearing failure

Thanks for the quick replies. The pump is old, probably original. Is it a matter of replacing the bearing or new pump altogether?

I think you have to just buy a new one.
There not expensive.