pin hole leak in head

[Jack Wright]

I am hoping for some advice on a pin hole leak that has developed in our A4. I have looked for existing threads describing this problem, but nothing so far fits my symtoms exactly.

The attached photo shows the situation: A pin hole leak between the port headbolts next to cyl. 1 & 2. The pin hole leaks about 1 drop/min at idle speed. Water collects in #2 spark plug recession, then boils off. A4 is salt-water cooled, no other leaks apparent at headbolts or otherwise, no water in oil or cylinders that I can detect, normal operating temp., and otherwise engine runs fine.

Any advice on how to approach this problem would be appreciated, especially whether it is possible to drill, tap, and plug the hole.

Thanks in advance for your help.

[jayw]

I think these areas were holes in the casting mold to allow air to escape when the metal was poured, and were plugged after the head was cast. You can probably use most anything to plug the hole since there is little pressure in the water jacket. You might consider epoxy (after cleaning the hole) or even a self-tapping screw with a bit of sealer.
I seem to remember some past posting of this problem so a search may give you more options.

[Jack Wright]

update on pin hole leak

Thanks jayw for the suggestion and clues on related links. If I understand what I've been able to piece together, my pinhole leak occurred where wire was used to suspend the block during casting.

In any event, I drilled, tapped, and plugged the hole with a machine screw and formagasket. So far, all is well.

Thanks to everyone for this very helpful forum.