Good to hear the pump was just an air pocket.
Do you have a lock washer on the bolt? They will leak out of the "split" if water is leaking to the bolt somewhere. Bolt torque could be a factor too.
MMI has an oversize stud set available. Then you could easily drill out the pieces that are snapped off, drill and tap the new threads and manifold and your good to go.
If you do have the lock washer leaking syndrome, carefully replacing with a flat or "star lock" should finish the season
. Then do the above for a good quality fix that will last.
Dave Neptune