Tired of running around hitting every auto parts store in the area just to find that that either they don't know what a helicoil is, or that they don't stock the one I need.
I stripped an exhaust stud removing my heat exchangers, and it turns out that the PO had helicoiled it once with an 8mm one. Luckily for my it looks like the coil itself failed, rather than the threads being stripped as the heliciol literally broke apart in pieces. I was able to get the pieces out fine, and now I have a replacement helicoil but cannot find the tool to save my life. I am trying to avoid buying the kit since I am only doing 1 stud, plus if the helicoil doesn't end up working I am going to just retap the threads to 10mm and be done with it.
Bottom line is I don't want to spend the $ on the kit when 1) I only need it for one stud and I already have the correct coil, and 2) I may end up not using it if the threads are indeed shot.

So, all I need is the actual tool that installs the Helicoil. Anyone local have one on hand they could loan me? If not local, I'd happily pay postage and throw in a few bucks for your trouble as it would still be cheaper than buying the $40+ kit, plus I need to save for a torque wrench too :-) Please PM me if you can help.

And on a side note, all the auto parts stores in my area suck. They're great if I want to buy a license plate frame or some cheap seat covers, but beyond that they are sorely lacking.

My advice is to take it to a machine shop and have an insert installed. My local shop was able to do it for $18 (parts and labor included). Way cheaper then I could have done it myself. Also an insert is going to last longer then a heliocoil.

Zach

You can make a tool to install a new helicoil, just need a hex bolt the size of the stud you'll be putting back into the hole when finished.
Helicoils have a "tang" that sticks out into the middle of the insert. You just need to file and shape the end of a bolt so that it creates a "shelf" on one side of the bolt and can engage the tang on the helicoil. Basically you just file down 1/2 of the diameter of the bolt... hmmm.. a little hard to describe this.
You file the end of the bolt across the diameter, a thread down or so, removing material off the end. This will create a "step" so that when you screw the bolt onto the helicoil, the tang will catch on the step and then stop, allowing you to then use the bolt to "screw" the helicoil onto the hole. It doesn't have to be a super accurate tool, just enough tto securely catch that tang on the helicoil.
Give it a try!

Jeff

Thanks Zach, but I am doing this with the engine in the car, and don't want to remove the engine at this point. If need be I will just tap the threads to 10mm, which would be better than in instert too I think.



Thanks Jeff, I was thinking about doing that actually, but wondered how I would cut the end of the helicoil off. The final threads of the original threads are ok, so I have almost 3/4" of good threads for the stud to grab, but only if I get the stud in all the way. Besides, with no way to cut the end of the helicoil off, how do I back my install tool (bolt) out without backing out the helicoil too?

In looking at the helicoil istelf, it almost looks like it won't fit in the hole (it fits on the 8mm exhaust stud ok). But I assume that the 'tang' catches and then coils the helicoil 'tighter' around the tool/bolt allowing it to thread in the hole. No?

Yup just make one out of a bolt.
The bevel on the back side of the tang should be at the same pitch as the thread. it screws in and drives the insert into the hole. as you back the tool out it will leave the insert in. you can use a SMALL sharp chisel to break the tang off. or just leave it in. I always put them in with some regular JB weld.

I've got a Recoil kit you can borrow. They're a competitor to Helicoil. I ordered 8mm helicoils from McMaster-Carr, and they substituted Recoils. I learned at work that you can't mix Recoil tools, taps, and inserts with Helicoil, but there are inserts in the kit and you're welcome to try it.

Also, I have a 9mm Timecert kit with extra inserts. If you can locate a 9mm/8mm stepped stud to use, that may be a better solution. You need your own tapwrench, which you use on the drill bit, tap, and insert tool.

I replaced a pulled exhaust stud on mine with the Timecert kit, in the car. Took about 10 minutes. Piece of cake.

Let me know.

Jim

It may be better and easier to get a step up stud and tap the hole for 9-10mm depending on the size you get.

I got a few step studs at a local VW shop for like a buck apiece. I wish I could find them, I'd send you one.

I think he should go bigger than 9mm thread. There's already been a helicoil installed, so he probably should either replace it, or better- go with a 9mm Timesert or 10mm stud. The 9mm Timesert taps a hole slightly larger than 10mm.

[quote]You can make a tool to install a new helicoil, just need a hex bolt the size of the stud you'll be putting back into the hole when finished.[/quote]

Thanks Jeff, I was thinking about doing that actually, but wondered how I would cut the end of the helicoil off. The final threads of the original threads are ok, so I have almost 3/4" of good threads for the stud to grab, but only if I get the stud in all the way. Besides, with no way to cut the end of the helicoil off, how do I back my install tool (bolt) out without backing out the helicoil too?

In looking at the helicoil istelf, it almost looks like it won't fit in the hole (it fits on the 8mm exhaust stud ok). But I assume that the 'tang' catches and then coils the helicoil 'tighter' around the tool/bolt allowing it to thread in the hole. No?
[/quote]

Yes, the insert tool "draws" the insert into the specially tapped hole with the tool pulling on the tang. The tool should act like a 1-way clutch, only grabbing the insert in the tightening direction - backing the tool out should dis-engage the tang and leave the insert fully in place.
The insert should be sized (lengthwise) to not leave any exposed insert sticking out of the hole when fully in there. Be sure to use the right length helicoil!
The tang can be broken off with a small screwdriver or whatever can be used to tap down into the hole and bend the tang, that'll break it off. Then just fish it out or let it fall out with gravity.

The new stud should only engage the helicoil, not part of the original hole/threads. I don't think there's any way to align a helicoil so that new and original threads are in perfect alignment! The full length of the stud should be engaged with the helicoil when it's fully installed. Sounds like the hole may need to be drilled/tapped deeper to use a full length helicoil?

As others have stated, Timecerts IMO are a superior thread repair, but much more $$$ for the kits! As each uses it's own special oversize tap to allow installing the insert I don't believe you can switch "mid-stream" from one type to another. You'd probably have to go further oversize and use a thick-wall Timecert, but that seems a little extreme.
Jeff

Timeserts use the same tap as Helicoils. The Cap'n

A big thanks to everyone for the replies!



Jim, thank you for your offer for an insert. There's a good chance I'll be taking you up on it, and will PM you soon.

I'm all for doing whatever will be a long time fix for this problem, although I'm a little nervous about tapping new threads, but it won't keep me from doing it.

So my next question is this:

Knowing that there's already been an 8mm helicoil installed in the past, should I use a 9mm timecert, or just tap the threads to 10mm? What's the advantages/disadvantages of both? Are there advantages in using a timecert over just retapping to 10mm thread size?

I believe Jake cells the step studs, either that or I'll start calling the local foreign auto repair places- the local VW shop did not have long enough studs in any thread size.

hmm. The weak link is the bite of the thread into the aluminum head. And both 9mm timecert and 10mm stud screw into a 10mm thread. (timecert VERY slightly larger than 10mm, but close enough.) A 10mm thread in aluminum can handle more torque than an 8mm thread in steel- so the other end of the stud becomes the weak link, torque-wise.

This sounds pretty logical, but I'll ask the experts at work tomorrow and see what they say about 10mm stud vs. timecert vs. helicoil.

As far as sources- Jake must stock the 8/9 stud. If not, these guys should have it- http://www.belmetric.com/html/catalog12.htm

Coincidentally, these are the guys that sold me my timecert kit.

Also, the kit works very smoothly. You drill the hole out by hand, using the bit in the kit on a tap wrench. The aluminum cuts like butter, but you can easily tell when the bit bottoms out. Then you counterbore the hole with the bit supplied- again using the tap wrench. Then you tap it with the tap in the kit in your tap wrench. Same thing about the butter.... Then start screwing the insert in with your fingers, and finish with the tool until it bottoms and locks.

Thanks for looking into this Jim- I really appreciate it. The link you gave is a good one too- I think I found it from one of your previous postings. I actually gave them a call yesterday and was told that they don't sell individual studs, but rather only in bulk to auto supply/repair shops. I haven't tried calling around at the local repair places yet because I wanted to make sure which stud I was going to use first. I look forward to hearing what you find out regarding timecert vs. just using a 10mm stud.

Well, I guess I'll stop recommending Bel-Metric in these posts. When I need something, I stop by, and they open their stocks to me. Let me poke around their panel truck, which is loaded with all the metric goodies in their catalog....

I don't have anything just now to bring me by, and they're about an hour outside of my marked territory. Like I said Jake must have these studs. I seem to recall (may be wrong) that the 9/8 step stud was standard on the 1.8L engine... so someone has them.

I'll let you know what I find out from the PhD mechanical engineers at work. When we make ANYTHING there are helicoils in every threaded hole in aluminum or magnesium.

If you're still willing to let me borrow the timecert kit, I think I'll go that route. I can borrow a craftsman rethread/tap kit from a friend so that should have the tap wrench (assuming the timecert tool will work with it ok).
I'll send you a PM. Thanks again for all the help- I'll be hitting Jakes site next to order a step stud.

It's in the mail. You should have it by Friday, or possibly Saturday. I couldn't find the instructions, but they're at the Timecert website. Main thing is to work slow and be sure to lubricate.

Checking with the guys at work brought these responses-

1. either 10mm stud, 9mm Timecert or 9mm helicoil (Recoil) will be about equivalent in terms of holding power. This is because any of the three will be stronger than that 8mm nut-on-stud at the other end of the stud, so that will now become the limit.

8mm anything isn't recommended because you may not have enough bite left- especially if it's a pulled stud....

2. Advantage of helicoil is that the thread has a tiny amount of give, which helps in a situation with big difference of thermal expansion. The stud will not expand as much as the pipe, even though CTE is similar, because it won't get as hot, and so significant stresses can build up in the stud and on the steel-to-aluminum thread interface.

On the first point, the factory (apparently) tried to mitigate the mismatch by installing 8/9 step studs on the 1.8L. Why not the 2.0? Well, I'm totally guessing, but the 2.0 was a VW casting, but machined to Porsche specs. So (still guessing here) maybe Porsche didn't see the need to change?

On the second point, heli-nuts were phased in. My only data point here is that my '76 2.0L used them. They are more expensive than plain locking nuts, so I've got to believe the factory was trying to fix some problem....

fruit for thought anyway.

Good luck!
Jim

Jim, your a lifesaver. I really appreciate the help and hope I can repay the favor some day. Just another reason why I love this site and the willingness of the people here to help others out.

I've already ordered a 9mm step stud from Jake, and with any luck everything will arrive at about the same time.
And I wasn't aware that the 1.8 liter had 9mm studs from the factory, wish they had put 'em on all the cars!