Engine mounting stud pulled from crankcase

[Jerome74911S]

One of the studs that attaches the engine mounting bracket to the crankcase has pulled out. I removed the bracket to address some oil leakage, and when I reinstalled it I torqued the nuts to 30 foot pounds (40 NM). However one of them did not tighten down, so I removed the bracket.

That stud was pulled, perhaps due to over-tightening by someone in the past.

Therefore, I drilled out the hole and tapped it for a HeliCoil. I was very careful not to drill any deeper than the original hole.

Here's my question: The coil insert accommodates 15mm of threads, however, the threads on the stud are 19mm long. What should be done about this? Can I stack two coils, one behind the other and then cut off the excess length? Or cut off the extra first? The hole is not deep enough to use two whole coils.

Or, should I just put in one coil and forget it? One connector is a bolt, rather than a stud (second photo) and it has 15mm of threads.

In the first picture I point to the damaged stud hole. There is little material into which to drill more deeply around the back side - if I'm correct.




The second photo shows the bolt hole with 15mm of thread depth. This is one of the four connection points for the engine mount bracket.

[Flat6pac]

The helicoil as a rule wont hold as well as an insert. For long term, I would look to a 12mm thread tap, insert a 10mm solid insert and youre good to go for long term.
Bruce

[Sigurd]

Install and use the HeliCoil. Threads 1.5 X the dia should be fine. Replace the bolt with a stud and you should be ready to go

[Jerome74911S]

Originally Posted by Sigurd

Install and use the HeliCoil. Threads 1.5 X the dia should be fine. Replace the bolt with a stud and you should be ready to go

Thank you. The stud is M10x1.5, therefore you are suggesting that 15mm of thread is OK. Right?

The bolt is original equipment - why change to a stud?

[Sigurd]

Yes on the HeliCoil.

Are you sure about the bolt? The parts diagram show part # 999 061 056 02, a 10 mm stud.

[Jerome74911S]

Yes, I'm sure about the bolt. There is very little clearance inside the bracket to fit that bolt into its hole, so a stud might be impossible to deal with. But then again, maybe somebody changed it to a bolt. I'll have a look at the PET.

[Jerome74911S]

You are right! The PET shows a stud in that location. So it seems that a PO changed it to a bolt. I can understand that change; it's a very awkward location.