Pin Hole In my J Head

Personally - when I go through (and it's happened a couple times) I toss the head and start again. I'd rather not have pressurized fluid behind an epoxy repair like that because eventually the repair will fail - but it's just me. You could try the epoxy on it. I don't think ceramic sealers will work on a hole. I've used them (Moroso) with success for seaping type leaks. The problem will be you'll need to bring the repair back the that shape or that one port is wrecked anyway.