What you describe is similar to the situation with the cam locking bolts.

It took no time to fuse. I had to redo the timing and within 1-2 days it took close to double the torque I set them with to loosen.

Hitting with a hammer first dropped the torque needed about 30%

Good you got them out, knowing you couldn't lose gave you the knowledge you could use as much torque as needed. I'm wondering if anti seize can be used when installing to make removal reasonable.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)