On a 351w water pump, there is that looooong bolt that goes through a water passage.

Can that bolt be removed and re-sealed without draining the coolant, or will it come pouring out when the bolt is removed?

When I last did my waterpump the bolt was a bit rusty and I meant to change it but forgot, now trying to figure out if I can just pull/seal the bolt, or better to wait for when I do a coolant flush?