Repair Damaged Or Worn Threads

NOTE:

If stripped/pulled threads are found during removal of a cylinder head or a main bearing cap bolt, the cylinder block must be replaced. DO NOT INSTALL A THREAD REPAIR KIT (Heli-Coil™).

CAUTION:

Be sure that the tapped holes maintain the original center line.

Damaged or worn threads can not be repaired in the following locations:

Spark plug threads in the cylinder head.
Camshaft bearing cap attaching threads.
Crankshaft main bearing cap bolt threads in the engine block.
Cylinder head bolt holes in the engine block.

On many applications, damaged or worn 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.
Installing an insert into the tapped hole to bring the hole back to its original thread size.