360 Magnum Crack....head bolt to water jacket

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thomasfouraker

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Purchased this used long block and when I was cleaning it up I noticed a poorly executed thread repair and a crack running from it to an adjacent water jacket. The threadsert sits up above the deck. How a cylinder head sealed I have no idea. No signs of moisture in the combustion chamber and the gasket that came off looked fine.

My question is was the thread repair put because of the crack or did the thread repair cause the crack.....?

If it passes a pressure test would y’all run it?

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Given the history of it holding good and not leaking before, I would take it to your local trusted machinist for a resurfacing an an opinion on the crack. There are some mechanical repair options I would trust for it (or grinding it out out and NiRod)but if the timesert is installed with Green Loctite or sealant I wouldn't sweat it.
 
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I would throw the block away. When the block heats up during use things will change. This is too risky to put money and time into.
 
To me it doesn’t look like it extends to the thread insert. It looks more like a tool mark off the water jacket which kind of lines up with the mark on the actual insert. Only way to know is to have it dye penned, mag particle inspection, or other means. My thought is if it is cracked due to thread insert it would more than likely propagate from the bolt hole.
 
I guess I should also ask what the overall plan is and how far from stock you are building it.
 
If it were mine, I would take it to a GOOD Mopar savvy machinist to have it checked out before I put any more money in it.
 
Hang on a minute fellas...

What is the failure mode??? The coolant passage into a thread.... NOT INTO THE CYLINDER!!!!

There are many threads that go directly into the coolant passages; the front and rear studs for the exhaust manifolds on the heads go into the water passage with pressurized coolant, the long water pump bolts also go into the water jacket in the front of the block...

Just put some sealant on the threads for that hole, or run that silver powdered stop leak in the cooling system for 40 minutes and it will stop any leaks through the threads....

I don't think there is much to be concerned about....

Grind the thread repair off that's sticking above the deck and run it...
 
Let me see if I can get a better picture of it.

As far as plans:

Its getting a forged 4" crank running around 9.0:1 compression with plans for lower boost (6lbs). Staying roller cam with lift sub .550" I imagine it should be 550hp once everything is done.
 
Get a different block. I wouldn't use anything other than a pristine block with no cracks or thread repair with that much boost on that much compression with four bolts per cylinder. That would be okay for almost anything else, but all bets are off with power adders.
 
It probably would work. But why bother with it? It looks like a garden variety worn out block. Nothing special. Toss it and get a different one.
 
gregcon said:
It probably would work. But why bother with it? It looks like a garden variety worn out block. Nothing special. Toss it and get a different one.
Click to expand...

The only up side is its already bored the .030 over needed and the bores still show cross hatch. Even with a hone job they should still spec the .0025 piston to wall clearance my pistons call for. So I guess it will save the price of that machine work but not worth risking if its compromised.
 
Put some sealer on the head bolt threads. I do it to all of them anyway. Send it.
 
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