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Mon Oct 10, 2022 4:10 pm

At the base of my alternator stand, the previous owner(s) have removed the original engine stud , and put an M8 bolt in it's place. The other 3 engine studs are fine and I can place nuts on them as needed. The bolt will not tighten into the threaded hole. It will only get so far before it pops loose again. I removed the bolt and the alternator stand and attempted to clean the threads in the hole, hoping that would fix the problem. not so much. What is the next best option? I have heard negative and positive reviews on the helicoil, but a lot of negative. I'm not sure the best way to fix this. Fix the hole, or buy a stud to return the set up back to the normal nut configuration.

I'm a little nervous about drilling into the case for this but I don't think I have any other option. Here is the current set up, you can see the bolt. Right now I have iut sitting in the hole, it goes in a little further before stripping.

Mon Oct 10, 2022 4:23 pm

If you don't want to use a heli-coil you can probably get away with using a stepped stud. Just tap the stripped hole the next size up and install an appropriately sized stepped stud. McMaster/Carr probably has just what you need.

Mon Oct 10, 2022 4:26 pm

You can always put a steel insert in. I did all 4 so i can use bolts instead of studs so I can remove the alternator without removing the fan shroud.

Mon Oct 10, 2022 4:44 pm

never having done this before, you don't actually use an M10x1.25 tap in the M8 hole right? You have to drill no matter what, right?

I guess there is no way around drilling. I do like both options above. 1. stepped stud, and 2. the steel insert. Option 1 might be the easiest option.

Mon Oct 10, 2022 4:50 pm

Put a stud in with some JB Weld.

It's a hack but will work.

Mon Oct 10, 2022 5:02 pm

Yep, always drill the proper sized hole before tapping. I like JB weld too. Lab-Metal also works great.

Mon Oct 10, 2022 5:04 pm

so if i go that jb weld route. i already have a M8 hole, minus the fouled up threads. would you screw in the M8 stud as is, as far as it would go, and let it set up?

Mon Oct 10, 2022 5:06 pm

I'd double nut the stud and drive it in as far as it will go and let it setup for a day or 2.

Mon Oct 10, 2022 5:10 pm

would you happen to know the stud length? I actually have M8x1.25 studs here that are 40mm long. would that work?

jb weld - is there a specific one to use? I have experience with one of them, but it was a putty.

Mon Oct 10, 2022 5:13 pm

M8x38mm. You should be able to get a 40mm at any ACE Hardware store.

Mon Oct 10, 2022 5:14 pm

I would just fix it correctly. A decent (offbrand) helicoil kit for m8 can be bought off amazon for less than $20. If I remember correctly, that hole doesn't go all the way through into the crank case, so there really is no reason to be scared of drilling. Even if it does go through to the crank case, small amount of magnesium chips that might get into the crank case are harmless and will likely just drain out on your next oil change.

Pickup a thread repair kit and a regular 8mm stud and you'll be all set. The 8mm thread repair sets are nice to have anyways, odds are this won't be the only stripped out hole you'll come across in your time with this car.

Mon Oct 10, 2022 5:19 pm

allamaabroad wrote: Even if it does go through to the crank case, small amount of magnesium chips that might get into the crank case are harmless and will likely just drain out on your next oil change.
Or get circulated and imbedded in the crank or rod bearings.

Magnesium is not magnetic so there's a good chance they could float around.

The smart thing is to measure the depth of the hole and put a piece of tape on the drill bit to mark how deep you go.

Mon Oct 10, 2022 5:30 pm

CB,
Careful with that fastener hole. It's open to the inside of the case there.

If you are thinking of drilling and tapping that fastener hole.
Stuff a clean rag into the filler penetration and fish it under the hole.
Like this,

Grease your drill bit to catch the case material being cut. Then tap the threads, with a greased tap. Carefully remove the rag.

If this were mine. I'd install a Time-Sert, available from amazon.
https://www.amazon.com/M8x1-25-Thread-Repair-1812-...13d670b6bc
ACN does not list this as a rental tool. At this time. Even though I have rented one there before.

Mon Oct 10, 2022 5:36 pm

67rustavenger wrote: ...
Picture is worth 1000 words... good job ;)

Mon Oct 10, 2022 5:56 pm

Glenn wrote: 67rustavenger wrote: ...
Picture is worth 1000 words... good job ;)
Thank. I try to help, where I can! :wink:

Mon Oct 10, 2022 7:33 pm

JB weld the stud in now, fix it correctly someday when the engine has to come apart.

Tue Oct 11, 2022 12:31 pm

For a normal STI tapped hole, a Helicoil is going to be the strongest repair. Most don’t want to hear it, but they are stronger than Timeserts. With Magnesium and aluminum, you need to use a prewinder to instal them properly. If you don’t use a prewinder tool to instal the Helicoil, the repair will almost certainly be weak. Prewinders are a bit pricey for what they are, but worth every penny, especially if you end up doing lots of Helicoils of that particular size.

Tue Oct 11, 2022 1:24 pm

I think I'm going to go the route of drilling out the hole to make it large enough for an M10. I'll order a M10 1.5 x M8 1.25 step stud and be done with it. (I hope)

I saw some step studs but they were only 38mm, is the 40mm stud the best option?

Tue Oct 11, 2022 1:31 pm

Heli-coil is the only thing to do!

Tue Oct 11, 2022 1:51 pm

There are e-z loks too
https://www.amazon.com/Z-LOK-Threaded-Insert-Metal/dp/B07V5WSZNJ