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I was doing service on the motor on Friday afternoon. I am pretty sure I originally had used grease (or maybe alu paste) on my screws, but I haven't changed the thermostate for a few years (don't see the need to do that when I can follow the temp on the plotter and see that it's OK), and the rear screw had corroded shut and broke. 
I am pretty sure I invented a few new swear words when that happened, because the boat is on a rented trailer, and here in Norway all repair shops are closed from Friday afternoon until Tuesday in Pentecost.
I tried to get the scew out by drilling into it and using a screw extractor, but no way. The only thing that did, was to destroy the part of the thread that's above the engine block itself. And this is something that I don't trust myself to fix. I need a solution that can be used for the rest of the engine's life. This doesn't have to be too long, since it has more than 2000 hours on the clock. In two years I retire, and I will set aside the retirement package so I can pay for a new motor when this one gives up the ghost.
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But maybe it can be fixed by drilling out the rest of the screw and use a thread repair insert. I hope there is enough that can be threaded in the engine block below the cracked part, if the strongest Loctite is used on the insert and a stud bolt, and I then use a nut to loosen the thermostate housing from now on.
If the depth of the hole is the same as the 19 mm on the other two holes, then there is 9 mm below the cracked part. But that's what I don't know, since I have not measured it, and I do not dare to drill deeper now (I'm 14 mm down now). Does anybody know that? If it needs welding, I'm probably looking at around 500-1000 USD in Norwegian money, getting work done is expensive here.
Oh, and if there is even more that can be drilled and threaded below the end of the original hole, that would be even better, but I'm scared that the drill will go through to the chamber, as far as I can see that is in the oil, not a cooling channel.
I am pretty sure I invented a few new swear words when that happened, because the boat is on a rented trailer, and here in Norway all repair shops are closed from Friday afternoon until Tuesday in Pentecost.I tried to get the scew out by drilling into it and using a screw extractor, but no way. The only thing that did, was to destroy the part of the thread that's above the engine block itself. And this is something that I don't trust myself to fix. I need a solution that can be used for the rest of the engine's life. This doesn't have to be too long, since it has more than 2000 hours on the clock. In two years I retire, and I will set aside the retirement package so I can pay for a new motor when this one gives up the ghost.
image.png.4cc6b1884f8e052840f8a59581cdd8be.png
But maybe it can be fixed by drilling out the rest of the screw and use a thread repair insert. I hope there is enough that can be threaded in the engine block below the cracked part, if the strongest Loctite is used on the insert and a stud bolt, and I then use a nut to loosen the thermostate housing from now on.
If the depth of the hole is the same as the 19 mm on the other two holes, then there is 9 mm below the cracked part. But that's what I don't know, since I have not measured it, and I do not dare to drill deeper now (I'm 14 mm down now). Does anybody know that? If it needs welding, I'm probably looking at around 500-1000 USD in Norwegian money, getting work done is expensive here.
Oh, and if there is even more that can be drilled and threaded below the end of the original hole, that would be even better, but I'm scared that the drill will go through to the chamber, as far as I can see that is in the oil, not a cooling channel.
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