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Discussion Starter #1 (Edited)
Details: 89 4.0 L engine, fresh rebuild of head and block 100 miles on engine

Fuck Up: Lent to Chrysler Mechanic to take to shop and scope. Mechanic overheats "until it affected engine performance" cause he forgot to replace cap on the turtle.

Performance: Appears to be unaffected.

Problem: Coolant leaks from front exhaust manifold stud during warm up
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Any ideas? I'll be doing a compression test, etc. this weekend. Anyone know if the front stud goes into the cooling jacket of the head? Have I cracked my head?

Planning on pulling out the stud, putting pipe dope on it and replacing. If it has a crack though, I'd need to pull the head and weld.
 

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VerticalScope Sucks
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It's cracked from the stud hole to the water jacket, most likely. It'll work fine other than it will leak a bit, and the crack will grow over time. Eventually the stud will probably start coming loose too.
 

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Discussion Starter #3
It's cracked from the stud hole to the water jacket, most likely. It'll work fine other than it will leak a bit, and the crack will grow over time. Eventually the stud will probably start coming loose too.
That's what I'm thinking, guess I'll see. Didn't know if the tapped hole was "open" to the water jacket or not.

If I can se in there enough, I may drill it to relieve stress before sealing the hole.
 

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Discussion Starter #4
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?
 

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Discussion Starter #5
It's cracked from the stud hole to the water jacket, most likely. It'll work fine other than it will leak a bit, and the crack will grow over time. Eventually the stud will probably start coming loose too.
WRONG!

Looks like the shop put the sealant for head bolt #11 on the wrong end!



I found out the hole for the headbolt DOES intersect the first hole for the exhaust manifold stud. Once I removed them both, coolant poured out of the exhaust manifold stud hole.

Sealant in the proper place, torque her down and all is good now!

 
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