Helicoil

[cmcfaul]

One of the studs that holds the oil pump pulled from the case when I tried to torque it last night. There is plenty of metal around the hole and I plan to use a Helicoil to repair the thread. Is this easy for the home mechanic?

I assume, drill, screw in the coil with loctite and done. Yes?

Thanks,

Chris

73 911 E

two steps forward one step backward.

[cmcfaul]

Found this. I am an expert now ;-)

Heli Coil Installation - YouTube

[HawgRyder]

First order of business is to make sure the tap goes in absolutely vertical!
This will make things so much easier.
Other than that...yes...the heli-coil can fix your problem.
Be advised the coils come in different lengths...try to use the longest one that fits...will give you the most hold.
Bob

[Walt Fricke]

As an expert, you now know it is drill, tap, insert, and put stud back in.

Helicoils don't use (or need, I think) locking products. You could use that on the stud, I suppose.

There is another type of insert suitable for home brewing. Drill oversize and tap. The insert is just a piece with threads on its outside, and (smaller) threads on the hole down its middle. It has a screw driver slot, and I think comes with a locking adhesive already applied. So once tapped, it is just screwed in.

I wouldn't have thought that something which can't be very stressed like this stud, and doesn't need much torque (and besides, the locking tabs should keep the nut from backing off) would have pulled, but I guess that is the mag case showing its age?

[cmcfaul]

Walt,

I agree, it should not have pulled. But when I removed the nut the stud came out instead. When I reinstalled it easily stripped. The torque specifications are a bit higher then I would have thought.

No big deal, easily fixed correctly. Just another delay in getting her back together.

Live and learn,

Chris

[PFM]

Chris,

The other thread repair system Walt is talking about is a TimeCert, this in my book offers a superior repair. FWIW look into both solutions and make an educated choice.

[Ken911]

Time certs are preferred over helicoils. They are stronger dont come unwound, stay in place better,no issues with the broken off tip ending up some place unretrievable, and easier to install. Also removal is easy just run a tap in it and it will come back out. The automotive OEM's have mostly went to using those on aluminum engines over helicoils.

[Walt Fricke]

The ones I am thinking of I believe are called case savers, or something like that.

Time Certs have long been the preferred way of dealing with head stud case threads on mag cases. But they are not, as far as I know, quite as simple for the home brew mechanic to deal with. They require very sharp taps (my machinist told me that the mag case dulls taps surprisingly quickly). And they are held in place with a roll tap, which finishes some of the threads. They are what I have had shops use on mag case motors, but when I've had to fix other threads I've just used Helicoils (for instance, the bolts which hold the transmission carrier to the chassis, whose threads are easy to strip), or my first experience when I foolishly opened up the steering rack and pinion while it was on the car, found nothing to adjust, but had one of the two cover plate bolts strip on me. That was a case saver gizmo gotten by a quick evening trip to the local super supplied hardware store, along with a drill, a 1/2" drill motor because the drill needed wouldn't fit my 3/8ths, and the tap needed, and has done the job for over 25 hard years on the SC. Subsequently I acquired first one size of Helicoil tool and some coils, and then a couple of other sizes, so those are my fix of choice because I have the stuff needed.

[otto_kretschmer]

I've used a helicoils to fix a stripped hole on my Honda XR350's engine years ago.

Piece of cake, just follow the instructions