Repair of Damaged or Worn Threads
REPAIR OF DAMAGED OR WORN THREADS
Damaged or worn threads (excluding spark plug and camshaft bearing cap attaching threads) can be repaired. Essentially, this repair consists of drilling out worn or damaged threads, tapping the hole with a special Heli-Coil Tap, (or equivalent) and installing an insert into the tapped hole. This brings the hole back to its original thread size.
CAUTION: Be sure that the tapped holes maintain the original center line.
Heli-Coil tools and inserts are readily available from automotive parts jobbers.