OK, I finally got a chance to do some testing yesterday. First of all, here is the leaking exhaust stud. You can see how the centerlines for the Head bolt and the exhaust stud line up:
Here's a closeup of the stud with the engine cold (these were cropped from an iPhone image, so sorry on the detail):
Notice the crusties from coolant leak last time it was driven...
Here it is after warm up. You can clearly see green coolant leaking from around the stud and washer. No leakage at all at the #11 head bolt (there is a white hazy material which I assume is sealant from when the shop assembled head and block):
Here's test results:
I did a cold compression check with all plugs removed and came up with:
138, 142, 145, 145, 145, 138, 138
A bit low on 1, 4, and 5.. but I'm thinking that's consistant with an engine that's gotten warm. I plan on retorquing.
Checked all spark plugs and everything looks good. All plugs firing cleanly.
Idles and runs nice.
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So, it doesn't appear as though there's a crack into the compustion chamber. If anything, I suspect there's a crack from exhaust stud hole to head bolt hole (or maybe it's drilled through?).
Here's what I'm planning to do:
1. Pull stud.
2. Examine best I can to see if crack or hole drilled through.
3. Seal with Locktite high temp thread sealant (same as used for Head Bolt 11).
I'm thinking I may want to pull the #11 bolt and reseal as well. Can I do this without loosening others?
Any other tips?