Hi,
I ALWAYS drill out torn breather screws.
I own the best affordable rewinders, but they are useless for this job.
Since you messed up nothing and saves much useless cheating.
I Did this more than one time even at calipers made of alloy.
Because: The shaft of the sealing cone has a smaller diameter than the thread. You can drill it off and then scratch out the remaining thread spiral. If the thread is MINOR damaged during drilling, it does not matter. The main thing is that the breather screw fits tightly afterwards.
The thread does not seal, only the cone at the end of the screw.
Click to view attachmentNote: The stem of the sealing cone has a diameter of <maybe> 5.5 mm. Exactly up to this drill diameter should be drilled in several stages (4 mm, 5 mm, 5.5 mm). Before drilling, insert a wire into the screw hole, then you know how deep you can drill at most! For example, Use insulating tape to mark this depth on the drill.
With the 5.5 mm drill you can not actually drill too deep - with the thinner ones already!
When drilling with the <maybe>5.5 mm drill, there will eventually be a small jerk - and the sealing cone 'turns free' because it is torn off.
Therefore, you can't actually drill too deep with the 5.5 mm drill.
Take the diameter at your new breather screw!The stem of the cone can be taken out / blown / rinsed with brake fluid after removing the thread test.
The picture shows no breather screw from the 914, only similar!
I wish you success
Norbert
- Sorry, I used metric dimensions because I firstly posted this at a German forum -