meek

Oh dear..

I was doing so well removing the heat exchanger, following all the great advice on RL, only to snap one stud. I have already tried removing it with MAPP and an Irwin bolt extractor, but all this ended up achieving was twisting off another piece of the stud; all I am left with now is what is seen in the picture below.

Am I better off drilling this out? I have trawled through a RL search of similar disasters and came up with the Stomski Racing kit: http://www.stomskiracing.com/products.php?id=8

Has anyone used one of these with success? It sounds like the most direct approach for me to take now, although it is a bit pricey and I will need to get a better quality drill. Still, if it is good it will be cheaper than towing my poor car to a specialist and having them fix it.

BigMikeATL

I don't see any signs of penetrating oil.

Soak that thing for a day and keep it drenched. Apply heat with a MAP torch and spray it again.the heat sucks the oil up into the threads. Soak some more and try some small vice grips. If that doesn't work, find or call someone that can wire weld a nut to the end of the stud.

meek

Oh, it was thoroughly soaked for a week prior to attempting removal today. Heat burns off the residual oil. My concern with attempting to turn it, with a welded on nut or with grips etc., is that it will just shear off again with a a messy stub partly below the head surface; that would make it hard to get a clean drill hole. The Irwin bolt remover certainly did grip and exert enough force, but the stud just doesn't want to turn. I have heated the head and tried, heated the head and frozen the stud, heated then soaked in oil again. No movement except for twisted metal.

I have the stub wrapped in cloth and soaking again now. Will try the mole-grips later, tentatively. I still think I am heading towards drilling it out, hence the post.

alexjc4

There's a tool called quikcenter that would work nicely on that stub to help you drill it out nicely. Nice sharp hss drill bit some cutting oil and a fairly high speed.

$8 for the m8 tool.
http://www.qbaroo.com/quikcentercom/

Not tried it myself but it looks suited to you situation. Not so good if its sheard flush tho.

Jacke2c

Try center punching with a point punch. Not real hard, but hard enough to get its attention. 100+ hits will help more than you can imagine. You still have quite a bit to work with. I would continue to heat, oil, and center punch for a while and then try with the "mole pliers" ie. "vice grips". If that fails, take the earlier advice and weld a nut to the stud. The penetrating heat of the weld and the leverage of the nut does the job typically. If that fails, buy the Stromski Kit. It will center your drill hole and leave you with a clean AND centered hole with original threads if you use the correct size bit with few further problems (time-sert, etc.). Stromski has been there and done that.

meek

Thanks for the advice guys. You are all right in that I should keep trying with what I have left of the stud. I will give it more time to soak again and then try again with the mole grips. I have used a drift and hammer to centre punch the stud repeatedly, along with the soaking, prior to my latest failed attempt. I will rinse and repeat the whole process. Then I will see if I can find someone who can weld and try that. If all else fails, there is the Stromski kit; I have put in an email to them on UK delivery etc.

Thanks again. I will report back on my success!

BobH20man

I had same problem and successfully removed using a MAPP tourch and vice grips. If shears off, then sounds like drilling is next step. Good luck.

meek

Fingers crossed Smiling because otherwise I might cry

alexjc4

Here's how that quikcentre works:


The stromski and similar pelican forum kits are great if you don't have a stump to work with and you need to index off the remaining stud and the exhaust port. But you have a stump to work with you just need a nicely centred hole.

The guy that drilled and helicoiled all 12 of mine charged less than the stromski kit!

meek

Thanks for the video link. All looks so simple in the video, but I am not convinced of its ability to drill dead centre (or my ability using it) and I only get one chance at that. The Stromski kit pretty much guarantees that; especially when I will be working under the car on my back. If some one has actually used the Quickcenter on their 911 and can tell me how simple it is, I may give it a try.

I can take the car to garage and get it done, but then I need a flat bed truck (C4) £££s and a garage £££s I can trust; too many experiences of 'experts', hence I am trying to do more myself. By the time I have done that, I will have exceeded the cost of the Stromski kit.

YaHoo!

I recently had the same issue. After soaking, tapping, using an extractor... I was left with a nub like what you have.
I ended up welding a nut on and immediately wrenched it out while red hot. It still required some muscle but it released.
If you decide to go this way then make sure to disconnect your battery- current from an electric welder can harm your DME and clip the ground close to your stud so the current doesn't have far to travel. I clipped it to the fin (seen in your pic) next to the stud and it was fine. I understand that if current travels a long way for an extended period it can result in sticking bearings...
Also expect a bit of corrosion to affect the welding process- I believe we burned through a rod and a half before we finally got a good weld.

Good luck- it feels great when you finally lick this beast!

MC

Arrivare

I have had similar problems in the past and made a drilling jig. It works really well with only one of the pair of studs broken but will also work with both studs broken. The plate is made from aluminium with 2 brass and 2 hardened steel guides. There is a spigot on the plate that is a good fit in the port and this is held in place with a single set screw that can be slackened off to keep the whole jig a good fit. The brass guides have a tight clearance hole for the exhaust studs. These are inserted in the plate and the spigot on the plate is pushed into the exhaust port. This works best if there is some stud left as it helps to centralise the jig. Then adjust the central set screw to get the jig to sit flat on the head. If one stud is ok put a nut and washer on and use this to tighten the jig into place. So the other hole in the jig will now be central over the broken stud. If the stud has broken at an angle, before fitting the jig, use a small grinder to get it as flat as possible to prevent stress on the pilot drill. Then fit the hardened bush with the small hole over the broken stud. I used a 4mm hole as this is strong enough to be able to put pressure on to drill the hole without bending. When this hole is complete put in the second hardened bush. This is sized for the tapping drill for the stud. Take off the jig and there is a tapping hole central and square in the stud. When done correctly all that is required is to use a tap to clean out the threads.
Unfortunately, I do not seem able to include a picture that should make everything clear so if you let me have your e-mail I will send a picture to you. (Or can someone explain how to insert a picture!)
I trust that this makes sense. Let me know if you need more information.
Allen

Arrivare

I notice that you are only 90 minutes drive away. You can borrow the jig if you like.

Allen

meek

Hi Allen. Many thanks for your post and extremely kind offer. I may just take you up on that. I attempted more heat, oil and mole-grips today, but no joy. Stopped before I chewed up what is left of the stud. My next step is to get a local welder in to weld a nut to the stud and see if the extra heat and grip helps. If it fails/shears off I will go for drilling. As was pointed out above, may as well try it as it makes no odds.

meek

Update. Fixed! With so much thanks to Allen (Arrivare) and his boundless help and advice. Using the jig that Allen made for his 964, I was able to remove the broken exhaust stud today. Sounds simple, but it did involve a visit from Allen and his lovely wife, with a 6 hour round trip(!), plus a few 'help me' 'phone calls. Ended up using a 15/64 drill bit supplied by Allen and then tapping out the remainder of the stud as best I could. It is not perfect (first turn of the thread is weak), but the fix is good. Now I can get on with fixing the oil line; which is why I removed the heat exchanger in the first place. Hopefully back on the road soon and a visit to Allen with a cake

Rennlist really is a great place.