TheSamba.com :: View topic

Wed Oct 15, 2008 7:21 pm

I know, Ive searched, point me in the right direction and lock her up. Having a hard time finding explanations of the actual process.

One of the exhaust studs is broken in my head (cylinder head :lol: ). What is the best way to remove it? Helicoil? Ok great, what is a helicoil and how does it work? What tools do I need to fix it?

I bought this
https://www2.cip1.com/ProductDetails.asp?ProductCode=VHD%2DN14%2D6841
but neeed to remove the old broken stud before that does me any good.

In the past when Ive had this problem, I just take it to a machine shop and overpay to have it fixed. Ihave been working on "mechanical" stuff for 15 years, but I have always feared removing a broken stud because I dont want to screw it up.

Can someone point me to a few good sites/threads so I can fix this myself. Lock the thread if need be, I know its in here somewhere, I just cant find specifics. Thanks.

Wed Oct 15, 2008 7:24 pm

cant you use vicegrips to grab it and twist it out?

Wed Oct 15, 2008 7:29 pm

Don't be so paranoid... there are reasons to lock some threads and other reasons not too...

Type 4 exhaust studs are a bitch to drill out and tap when in the vehicle/head not removed... so... IF there is a bit of the stud still sticking out and you have access to a mig welder then you should try welding a nut on and removing what is left while it is STILL NEAR RED HOT... othewise if it is broken off flush try to center punch it and drill it out dead center the best you can.

http://www.thesamba.com/vw/forum/viewtopic.php?t=279625&highlight=stud+weld

http://www.thesamba.com/vw/forum/viewtopic.php?t=254551highlight=stud+weld

Or click on this link that takes you to some other threads that might help if you weed through a "short search"

http://www.thesamba.com/vw/forum/search.php?search..._chars=200

Wed Oct 15, 2008 7:34 pm

If you've got a really good tool store, you can buy a reverse thread drill bit. If you use it to drill out the center of the stud, it will take the pressure off and sometimes spin it right out.

Wed Oct 15, 2008 7:36 pm

Not worried about the thread being locked. Ive been here long enough to know the redundant questions get annoying. I just need some answers, then it should be locked, or ignored.

There is virtually NO thread sticking out. Maybe half a revolution. The head is not in the bus so that makes things a little easier. I read both of the threads above, thanks kiefernet (Im sending you throttle plates soon to be re-bushed!), but I think I am going to have to drill it out. What does this entail? Thanks.

Wed Oct 15, 2008 7:38 pm

Westy Steve, I actually believe I have one of those "reverse" thread drill bit (friend of mine bought me the kit the last time I had this problem, but I ended up taking the head to the machine shop), but the sizes are all standard, not metric. Does that matter? would I just drill a small hole into the center of the stud and then use the "reverse" thread drill bits? Thanks again.

Wed Oct 15, 2008 7:50 pm

busmania24 wrote: Westy Steve, I actually believe I have one of those "reverse" thread drill bit (friend of mine bought me the kit the last time I had this problem, but I ended up taking the head to the machine shop), but the sizes are all standard, not metric. Does that matter? would I just drill a small hole into the center of the stud and then use the "reverse" thread drill bits? Thanks again.

Yes...as big as you can get without getting into the thread of the bolt hole. You might want to make a small pilot hole first as it is very hard to hold the drill steady. I wouldn't even use the conventional "normal" threaded drill bits during the whole operation.

Steve

Wed Oct 15, 2008 8:29 pm

Since the head is off your in much better shape than I anticipated...

Not trying to diss Steve but my experience does not lead me to trust the LH style bits right off the bat....

Use a center punch and get a good strike dead center. I would still use a regular rotation small bit or two moving up in size if you are still centered....get a good hole dead center before trying any " reverse rotation bits" as they can "snap off" like an EZ OUT ( another thing I would not use on EXHAUST STUD) and then you will PLAY HELL drilling out around that....

IF you get it drilled out about 1/2 size diameter of stud or more then you can try the reverse drill deal or ... but IMHO drilling out like with normal rotation bits and re tapping or using over sized adapter studs or time serts etc it safer than breaking off a reverse bit or EZ out.

Wed Oct 15, 2008 8:56 pm

this is not disrepectful. If you need to ask this question how to then you need it to go to a pro. I am 58 and among other things have spent years working on cars, race cars and as a machinist. I would pass on this one. The suggestion to try welding too it is a good one if you then soak it with penetrating oil for 24 hours before trying again. This stud has gotten hot and cold many times, it has bound to the aluminium in the head and they think they are one. To drill it out, whether reverse or regular. the first obstacle that you face is the placement of the stud. It is upside down and you will have to drill straight up. While you are doing this, hot metal shavings will be falling in your eyes and face as the drill bit bites into the stud and cuts which makes the metal very hot. If the heating and cooling of the studs has hardened the stud then you will need to keep oil on the stud as you drill as the hardness will destroy drill bits in a few seconds if they are not kept cool with oil. This oil will also be dripping all over your face.

First you will get the right drill bits, they will consist of hardened machine steel or high quality tungsten bits, not cheap ones from Home Depot. You will keep the stud wet with penatrating oil for at least 24 hours - soak a small piece of cloth and keep it on it. You will not use WD40 or regular oil because penetrating oil has a small amount of acid and chemicals in it that help eat rust away plus seep into the voids between the stud and aluminum. It may comes out easier with the oil. I have taken studs out with a screw driver sometimes once they soak that snapped a stud the day before. You will center punch the stud exactly in the center. You will drill a small, less than 1/8," hole into the stud until you either feel it go through the steel or it is about 3/8" to 1/2" deep, which ever comes first. You do not want to drill into the head. You will then drill with a 1/8" drill to enlarge that hole. If you are off center or the drill walks you will use the every slightly increasing drill bits to try to keep the hole centered. As the stud begins to get thinner, you will put an easy out in it and try to unscrew the stud with it. If you try too hard and break off a drill bit or the easy out you are screwed. If you have to go all the way to drilling the whole stud out, then you will need a helicoil kit for that size thread. I THINK BUT AM NOT SURE it is M8 1.25. When the stud comes out you will use the correct tap to chase the threads before putting in a new stud. Or you can pull the engine, pull the heads off and have all the studs replaced while they redo the heads. I used RIMCO in Southern California to redo my heads a few weeks ago. They replaced the valves, seats, guides, studs and welded up the cracks plus re-tempered the heads for about $350 each. My heads are German and are made better than the replacement heads today. A good machine shop will use a set of clamps to hold the head down to a pivot table and use their drill press so they can center on the stud before they drill, and it will remain true and not walk on the stud. If they screw up and cut into the aluminium they can heliarc the hole and re-tap it. Personally if it were me, I would be very upset right now but I would not try this lying on my back, hot steel pieces falling on my face and oil dripping into my eyes, mouth and nose. Maybe a diver's mask might help with hand towels drapped across what it doesn't cover. If you do try it, go slow and start with small drills every hole getting slightly larger. Do not be in a hurry. A good drill bit must be kept wet with oil to keep it cool and biting. If it stops biting go get another bit the same size. Do not wiggle the drill because if you snap off the drill bit you are in REALLY big trouble. If at ANY time the stud starts to turn with the drill you should either use a reverse drill of the same size or try an easy out immediately because it will mean the stud is loose. Personally based upon how tight mine were in, I elected to have the machine shop pull them rather than me because I didn't feel that lucky and I have removed hundreds of exhaust studs in my life. Aluminum and steel sometimes do not make for good companions.

There is one other thing you can try if the welding or drilling frighten you (which they would me). After you soak the stud with peneatraing oil for 24 hours, you can try using a dremel or a hacksaw blade to cut a very small slot into whatever is sticking out. Try to use a regular screw driver to barely fit into that grove and see if the stud will turn. I use a metal cutting disc on a dremel because it cuts deeper in the center. Sometimes that is enough to get a bite with a screwdriver in the center but not too deep to cut the aluminum next to the stud. Good Luck

Wed Oct 15, 2008 9:16 pm

Heat the stud and drip candle wax on it. The wax will flow down the threads.

Thu Oct 16, 2008 4:25 am

I'm with keith on this one - be VERY CAREFUL using easy-outs. Whatever you do don't break it in the old stud or you will be SOL.

Thu Oct 16, 2008 6:04 am

SGKent wrote: this is not disrepectful. If you need to ask this question how to then you need it to go to a pro. I am 58 and among other things have spent years working on cars, race cars and as a machinist. I would pass on this one. The suggestion to try welding too it is a good one if you then soak it with penetrating oil for 24 hours before trying again. This stud has gotten hot and cold many times, it has bound to the aluminium in the head and they think they are one. To drill it out, whether reverse or regular. the first obstacle that you face is the placement of the stud. It is upside down and you will have to drill straight up. While you are doing this, hot metal shavings will be falling in your eyes and face as the drill bit bites into the stud and cuts which makes the metal very hot. If the heating and cooling of the studs has hardened the stud then you will need to keep oil on the stud as you drill as the hardness will destroy drill bits in a few seconds if they are not kept cool with oil. This oil will also be dripping all over your face.

First you will get the right drill bits, they will consist of hardened machine steel or high quality tungsten bits, not cheap ones from Home Depot. You will keep the stud wet with penatrating oil for at least 24 hours - soak a small piece of cloth and keep it on it. You will not use WD40 or regular oil because penetrating oil has a small amount of acid and chemicals in it that help eat rust away plus seep into the voids between the stud and aluminum. It may comes out easier with the oil. I have taken studs out with a screw driver sometimes once they soak that snapped a stud the day before. You will center punch the stud exactly in the center. You will drill a small, less than 1/8," hole into the stud until you either feel it go through the steel or it is about 3/8" to 1/2" deep, which ever comes first. You do not want to drill into the head. You will then drill with a 1/8" drill to enlarge that hole. If you are off center or the drill walks you will use the every slightly increasing drill bits to try to keep the hole centered. As the stud begins to get thinner, you will put an easy out in it and try to unscrew the stud with it. If you try too hard and break off a drill bit or the easy out you are screwed. If you have to go all the way to drilling the whole stud out, then you will need a helicoil kit for that size thread. I THINK BUT AM NOT SURE it is M8 1.25. When the stud comes out you will use the correct tap to chase the threads before putting in a new stud. Or you can pull the engine, pull the heads off and have all the studs replaced while they redo the heads. I used RIMCO in Southern California to redo my heads a few weeks ago. They replaced the valves, seats, guides, studs and welded up the cracks plus re-tempered the heads for about $350 each. My heads are German and are made better than the replacement heads today. A good machine shop will use a set of clamps to hold the head down to a pivot table and use their drill press so they can center on the stud before they drill, and it will remain true and not walk on the stud. If they screw up and cut into the aluminium they can heliarc the hole and re-tap it. Personally if it were me, I would be very upset right now but I would not try this lying on my back, hot steel pieces falling on my face and oil dripping into my eyes, mouth and nose. Maybe a diver's mask might help with hand towels drapped across what it doesn't cover. If you do try it, go slow and start with small drills every hole getting slightly larger. Do not be in a hurry. A good drill bit must be kept wet with oil to keep it cool and biting. If it stops biting go get another bit the same size. Do not wiggle the drill because if you snap off the drill bit you are in REALLY big trouble. If at ANY time the stud starts to turn with the drill you should either use a reverse drill of the same size or try an easy out immediately because it will mean the stud is loose. Personally based upon how tight mine were in, I elected to have the machine shop pull them rather than me because I didn't feel that lucky and I have removed hundreds of exhaust studs in my life. Aluminum and steel sometimes do not make for good companions.

There is one other thing you can try if the welding or drilling frighten you (which they would me). After you soak the stud with peneatraing oil for 24 hours, you can try using a dremel or a hacksaw blade to cut a very small slot into whatever is sticking out. Try to use a regular screw driver to barely fit into that grove and see if the stud will turn. I use a metal cutting disc on a dremel because it cuts deeper in the center. Sometimes that is enough to get a bite with a screwdriver in the center but not too deep to cut the aluminum next to the stud. Good Luck

Some good advice... Lucky for him he stated the head is off the engine so he has a better chance of doing it himself or running it down to a machine shop is probably best ( if he does not own a good drill /bit/tools required. One could easily rack up the cost of having it done or more if they have to go out and buy the tools needed.

Thu Oct 16, 2008 6:18 am

Just invest in some carbide burr bits and eat the broken section of the drill bits and ez-outs out of the shanks if you break them off inside.It may cost the first time,but it'll pay for themselves after the first use.

Thu Oct 16, 2008 7:24 am

Thanks everyone. I think what I am going to do is practice first on an hold head that is no good. If I screw that up too bad, I will just take it into a shop, but I dont like paying people to do my dirty work. Great advice from everyone and it has definately cleared some things up. Thank you.

Thu Oct 16, 2008 8:30 am

The welding tip is a good one, but you don't have to weld a nut on it...just a nub that's beefy enough to accept vice grips. I've done this a couple times with great success...every easy out I've tried has broken off...

Thu Oct 16, 2008 9:11 am

Quote: The welding tip is a good one, but you don't have to weld a nut on it...just a nub that's beefy enough to accept vice grips. I've done this a couple times with great success...every easy out I've tried has broken off...

This welding idea sounds better and better. It may be a good excuse to give the economy a small boost and go buy a welder. I sold my welder (one of the hardest decisions Ive made) a few months ago and have regretted it since.

What kind of problems arise with the aluminum around the broken stud if I weld to the stud? Anything?

Thanks again.