I'm looking for advice or information on threaded insert (heli-coil) repair for exhaust studs on a Lycoming O-320. Hopefully Lycoming publishes some sort of service instruction or maintenance publication.
My #4 cylinder has one stud that has apparently already been repaired once with a heli-coil, and the stud was quite loose. Digging further, the stud threaded out of the cylinder by hand and brought the heli-coil with it, and the female threads in the stud hole aren't pretty. I'm not sure if there is such a thing as an oversize heli-coil to repair this with. The stud hole is getting pretty big.
I have heard that cylinder repair shops sometimes weld the stud hole closed and then re-drill and tap for the stud. If it's best to go that route, wondering what the cost might be. I doubt a repair shop would want to send out a cylinder that hadn't been fully reconditioned...
Thanks in advance!
My #4 cylinder has one stud that has apparently already been repaired once with a heli-coil, and the stud was quite loose. Digging further, the stud threaded out of the cylinder by hand and brought the heli-coil with it, and the female threads in the stud hole aren't pretty. I'm not sure if there is such a thing as an oversize heli-coil to repair this with. The stud hole is getting pretty big.
I have heard that cylinder repair shops sometimes weld the stud hole closed and then re-drill and tap for the stud. If it's best to go that route, wondering what the cost might be. I doubt a repair shop would want to send out a cylinder that hadn't been fully reconditioned...
Thanks in advance!