New Service to Repair Stripped Head Studs

[Carl Fausett]

We have a new process to repair stripped-out threads in 928 blocks.

Some 928 engines are "junked" only because of a stripped head stud or head bolt. These engines can be repaired and put back into service.

Our thread repair is the correct length to fully engage all the threads in the head stud as designed. Other thread inserts shown in the photo below are too short, and apply all the load to a lesser number of engagements with the block, and that's why they fail and pull out.

Further, our thread insert uses a buttress-thread between the insert and the block, so as not to exert any outward forces upon the casting. The shape of common thread inserts is beveled, and pushes outward on the block as the stud is drawn up. This can cause cracking of the block, and failure of the insert. For this reason, our insert repair process actually strengthens the block, instead of weakening it like others do.

These have been inserted and tested and shown to hold full factory head stud torque as well or better than an undamaged stud.

A 928 bare block in a heavy cardboard box with padding will weigh about 100 pounds, and they ship via UPS ground. Turn-around time is about 1 week on this repair.

[BlueMaxMtl]

It's nice to know that there's hope in the event that a stud does break flush with a head.

Hopefully it won't happen to a Gen-I 32V engine while it's still in the bay!

Thanks for sharing Carl!

[Carl Fausett]

Thank you, but just to clarify, this repair is not for a broken stud. It is a repair for head stud or head bolt threeads that have been pulled out from the block, which (unfortunately) I have seen on 32v engines with studs.

The 4-step torque process Porsche calls for (20 Nm, then 90 degree, then 90 degree, then 90 degree) is brutal on the block, and about 140 ft. lbs by the time its done.