Manifold Repair ?

go to www.marineexhaustmainfolds.com and get a new set and ask for PCM brand instead of the osco mainfolds both are at the same price and get the hardware kit as well. Take the risers to a local machine shop and have them diped to clean them out and reuse them unless it has been used in salt water regularly then they need replaced as well.

If the mainfolds are rusting through in one spot they rusting in other spots that you cannot see or get to to repair.

Was the boat used in salt water?? If you stab the spot where it leaks, you can tell if its thin due to rust. Some split due to improper draining,(like my old engine where someone welded up the manifolds). Like the others mentioned, dont mess around with the old ones....... Buy new ones!!

It turned out to be a freeze crack that someone tried to repair, so I replaced it....thanks

Trying to batch a leaky mainfold isn't a wise choice at all. And if I was you SMay I would be replacing the mainfold as soon as I could otherwise you are going to find out why you don't want to batch them, while your rebuilding your motor after you find out why.

If it's rusted through in one place where is the next place going to be? somewhere easy to batch again or somewhere else where you can't get to, like the inner wall of the water jacket??? and then your trying to figure out why there's water in the cylinders and it's hydro locked???