Taking one of the nuts off, the stud broke.

I welded a nut to the end of the stud so I could get a socket on it, but she doesn't want to turn. Feels like it will break again. So I've been hitting the stud with PB Blaster. I could heat it with a torch. Hopefully it will come loose, but I may end up having to drill the thing out and tap the hole for a step stud. Grr, right before WCR

Any suggestions?

Heat it up with a torch

Probably a stoopid question.... If you heat up the stud, won't it expand and make it more difficult to remove? How about a bit of dry ice no the end of the stud (cooling = contraction, heating =expansion)?

OTOH, probably not enough surface area to get the cold to propogate doen the stud...

Help! I'm a'll confused!

Eric Read

Eric, you are right, but I wouldn't be trying to turn it while it's still hot. The heat technique is a cycle - heat it, let it cool, then try and turn it. Sometimes that expansion / contraction will help it loosen up.

My local machineist taught me to heat up that area surrounding the stuck stud, and then put a cold wet rag on the stud to make it quickly contract while the surrounding metal was still hot.

This has worked on the one really bitch of a stud I have had yet to pull, though I watched him do it while hoping I would not have to repeat the performance.

Zach

The heat will break the rust or if someone used loctite in there. After I broke 2 on the first engine I had I never tried removing them again without heating them up first. Works everytime now.

The next time I have a stuck one, I might try welding a nut on it and using an air impact wrench to remove it. I did not have one the last time I had a stuck stud. Somehow, the impact wrench seems gentler then the heat and vice grips that I have usd in the past. Never tried it though, so I don't know.

Zach

Thanks for the explanation

Eric

Damn Rand, that's a bummer. Try heating it up and keep us posted.

I've encountered every level of "frozen" when dealing with exhaust studs. I have also tried every trick for removing them. The only method that works consistently is heat and PB Blaster. Don't let the head cool to much or the stud will just freeze back up. Heat the boss, but not the stud itself (it weakens the steel) spray it with PB. When the head cools enough th stop boiling the PB then try to break the stud loose. If it won't budge then heat again. If it budges don't get greedy. Rotate the stud back and forth to the extent that it will move freely while spraying it PB. Increase the amount that you try to unscrew slightly all the while twisting back and forth. The rotating back and forth helps work the stud loose. If you try to unwind it all at once (if it's really frozen in there) it will break. Some studs will break and that is just all there is to it.

BTW Zach I tried the nut weld/impact idea. Seemed like a good idea, but it just broke the stud nearly every time. The key is heat and gentle application of torque while rocking back and forth. It's a high profanity operation anyway you slice it when laying under a car.

Thanks Len!

I also have a stripped stud (me and my exhaust stud luck lately).

Len, what method would you use to repair stipped studs with engine in car? I'm not real fond of helicoils. I know time-serts are popular. But I like the idea of just going with a larger step stud. Thoughts?

So, when installing the new stud.... What is the best practice? Just screw it in dry? Or some kind of treatment?

Rand, when I stripped an exhaust stud last winter, after much research I went with the TimeCert over the Helicoil. Seems like a lot of people point to Helicoils as something that will eventually fail.

I also went to a 8x9mm step stud. This means using the 9mm TimeCert tap which taps threads to slightly larger than 10mm (to allow the insertion of the TimeCert).

I went with 8x9 based on advice from another here who feels that by only tapping to 9mm for the TimeCert (which allows you to use an 8x8mm stud) increases the chance of the stud stripping again due to lack of 'bite' on the 9mm threads, which is too close to the original 8mm threads.

If that's confusing, let me know- I'm operating on minimal sleep right now.


By the way, I was able to do this with the engine in the car. In hindsight it was really pretty easy. However, I was pretty puckered up during the entire process for fear of fuching things up. The process is still very much burned into my brain, so if you need help let me know!

Arr! The bastard put up a fight, but I won. Well, at least the first battle so far...

So, welding the nut to the stud didn't end up working... It just twisted off. That stud was stuck tight. And being so small, I couldn't get enough welding surface to have any success with the welded nut idea.

So.... Welded a piece of flatbar along side the stud. That way I could get a good weld on both sides of the stud to the flatbar and get some real power on it. A crescent wrench can grab the flatbar....

Then my only problem would be if it just broke the stud again. I was prepared to drill and tap at that point. BUT... First, use technique...

Heated the head around the stud with a mapp gas torch. Sprayed PB Blaster at the threads. Started to twist... Not just try and unscrew the thing - it's seized too tight for that. But... back and forth a little (as Len mentioned). It began to move.

Each time, as starting to unscrew more it would bind more. So, more heat, more PB Blaster, more twisting back and forth. As it freed up, kept working it out.

Done!

Now on to installing new studs.

Visuals, see pic below...

Left: The broken stud with the flatbar welded to it. Yeah, crude, but I got it out.

Middle: The stripped stud that started this whole mess. Note the galled threads at the head end (bottom), full of aluminum from the head. I'll be drilling and tapping that hole for a larger step stud.

Right: A new step stud. Only problem is, this is the longest one my local VW shop had, and it is shorter than I want.

I'm hoping I can find a couple of longer step studs locally tomorrow so I can fix this thing on my lunch break and drive it to WCR.

If you can find a timesert kit locally you could have it back on the road pretty quickly.

when drilling, gauge the depth and put a bit of tape on the bit so you don't drill to deep. you REALLY don't want to go too deep.

I once used a "Keylock insert" from Mcmaster carr. I think the OD is about 10mm (maybe 12). You drill and tap the head. The difference is it is held in place by 4 small keys that are stamped between the od of the threaded insert and the tapped hole. This prevents removal. I did need to modify the tap used to allow the threaded hole to tapped deeper. A step stud was not necessary. These are available in stainless steel.

? whats a PB blaster

PB Blaster is a penetrating lubricant. One of the best.

[quote name='Rand' date='Jul 10 2008, 11:20 AM' post='1054556']
PB Blaster is a penetrating lubricant. One of the best.


[/quote

Cool thanks! is that the same stuff they use on the frozen lock tumblers? and can you get it at your local auto parts...hows the fix coming

Where do I find PB. NAPA?

Put in a Subaru?

Stupid snarky answer, but thinking about it a little more I realize that could be the answer to nearly every question asked in these forums. Hmmm....

I agree that heat generally works well for exhaust studs, but sometimes it's just not enough, even with PB or equivalent.

That's when I take a hammer and beat the shit out of it. Okay, don't actually beat the shit out of it, but tapping on the end of the stud will send vibrations into the boss which will sometimes help break loose rust. I try to avoid using PB or equivalent when mixing with heat, because if you're not careful you will start a fire. So instead I opt for heat and hammer. Hasn't failed me yet.

RAND... I have one word for you... Tacoma Screw. Wait, that's two...

Go there and you will find all of your needs. Right down the street from you too.

Funny you should mention them. I went there on my lunch break. They didn't have any step studs... They had some studs, but none with a larger end.

Oh well, the one I have will work. It's a little short, but I can get a nut on it. I think I'm good to go. But won't be able to finish this until tomorrow.

Yup, most FLAPS have it.

Back on the road. The new studs held up to torque and no leaks. Whew.

The one step-stud that's a little on the short side turned out to be just long enough... All the threads are engaged with one to spare.

Drove it to the office and back today. Going to re-torque and head out to Issaquah.

Nice job Rand!!

After installing the new exchangers last year (and tapping new threads ) I still have an exhaust leak on one side and will be removing the exchangers again try and and fix. I REALLY hate having to do anything that involves exhaust studs and hope I don't find one that decides not play nice.

This is the last thing I have to do to drive the car to ECC. But can I do it?

did this happen after you and root installed the engine?

i had a welding stuff salesman at work the other day who actualy had something interesting ,if you break a stud or bolt and the rest of it sits deep in the hole, you usualy center drill the remains of the bolt("center "is a city in albania) tap in an extractor, twist and watch it break (the extractor that is) the you go buy lots of beer. not so with this shit ,actualy a electric welding(arc ) rod covered with graphite, you just put the rod in the hole making contact with the stud and just fill the hole to the top with weld then mig on a nut and twist. the graphite will form a layer betveen the weld core and the treads of the hole so they are undamaged ,he actualy pulled a M12 stud sitting 4inces down been welding for some time ,but never seen this

We found one stud was stripped and would not hold the nut so I have to replace it. I'm picking up my car from root's shop on Friday and I've ordered 2 replacement studs and two oversized replacement studs. I bought stud extractors from sears and a can of PB blaster. Doesn't sound bad but root says I can't drive it like that becasue the leak will cause additional heat and eat a hole through my manafold where it bolts to the head. I am so bummed. It is perfectly timed and doesn't appear to be leaking anything.