Snapped off rocker arm bolt - PeachParts Mercedes-Benz Forum

Frank Reiner · #1 11-10-2020, 02:21 PM

Quote:

Originally Posted by carneades

The most likely scenario, it seems to me, is that I tightened to spec or beyond by accident before I put the torque wrench on, and so, since I was already over the limit I set on the wrench, I never got any feedback from it. If this is true, then I have massively over-torqued the bolt, extracting it will be very difficult, and I fear for the threads in the head.

Quote:

Originally Posted by carneades

I'll do the protrusion comparison this weekend.

1) [See highlight] If the bolt had already been tightened to a torque that was greater than the setting on the wrench, then the wrench would immediately click without any further rotation of the bolt.

2) Insert the bolt with washer thru the shaft stand and observe the number of threads exposed. Five or more, no problem. If four, just make sure that the torque wrench is set correctly.

carneades · #2 11-10-2020, 08:55 PM

Quote:

Originally Posted by Frank Reiner

1) [See highlight] If the bolt had already been tightened to a torque that was greater than the setting on the wrench, then the wrench would immediately click without any further rotation of the bolt.

That's the behavior I'd hope to see, but I've never started a torque wrench in over-torque, so I didn't know what to expect.

Quote:

Originally Posted by Frank Reiner

2) Insert the bolt with washer thru the shaft stand and observe the number of threads exposed. Five or more, no problem. If four, just make sure that the torque wrench is set correctly.

I decided to go ahead and look at this. Here is a photo. The perspective makes it hard to see the relative lengths, but there are certainly more than five threads exposed. What is special about that threshold?