removing broken head bolt

[34PackardRoadsta]

Dear All,

Well, I perhaps screwed things up. I am removing and replacing all the head bolts (I don't trust the 78 year old metal). In the removal process, I had one break off right at the block. I put very little torque on it before it broke, so I guess it is probably a good idea to replace them. But, now I have a bolt in my block. Any good tricks I should try for removal?

Thanks,

Tom

[Phils38cpe]

If the bolt is broken off even with the block I would think you will have to remove the head.

If you have a welder you can place a nut over the broken piece and fill the hole in the nut with weld.Other than that you're pretty much limited to an EZ out

[mrpushbutton]

If you go the EZ out route heat the area around the broken stud as hot as you can logically get it and light a candle made of parafin wax, and drip the melted wax onto the broken stud. hopefully the area around the stud is still hot from the torch heating. This will pull the parafin wax down into the threads and help lubricate the threads for extraction. If you are at all doubtful about this get professional help.

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mrpushbutton</div><div class="ubbcode-body">If you go the EZ out route heat the area around the broken stud as hot as you can logically get it and light a candle made of parafin wax, and drip the melted wax onto the broken stud. hopefully the area around the stud is still hot from the torch heating. This will pull the parafin wax down into the threads and help lubricate the threads for extraction. If you are at all doubtful about this get professional help. </div></div>

Good idea with the parafin wax.

Given that I probably can't get another cylinder block with ease, I may see if I can get a machine shop to do this. I don't have a drill press, so I am not very excited about trying to drill a straight hole into the stud remainder.

Thanks all for your help.

Tom

[Guest imported_PackardV8]

If the stud is broken off even or nearly even with top of block:

Drill a hole in the center of a 1/4 or preferably 3/8 inch thick piece of scrap steel big enuf to catch two other bolts on either side. This is a drill guide. Place the drill guide so that the centre hole is exactly centered over the broken stud and bolt it down firm at the two end holes. Now, drill out the stud big enuf to get the largest possible ezout into the hole. Probably won't even need the ez out. The drill guide keeps the drill perfectly centered.

Ez outs have thier place but are highly over rated. Generaly not for rusted or otherwise seized bolts. If u break off an ez out or a drill bit in the hole then u are in BIG TROUBLE.

[34PackardRoadsta]

Hmmm, big trouble doesn't sound like a great thing . I like the idea of the drill guide. Thanks,

Tom

[Guest imported_PackardV8]

When using the drill guide u mite want to start out with a drill bit that is about 1/2 the diameter or a little smaller than the bolt u are trying to drill out. Then progress in 1/64 or 1/32 increments until u reach a drill size about 1/32 or 1/16 less than the original tap-drill size.

At that point u can usualy shell out the remaining amount of broken bolt because so much tension has been relieved. Or use the easy out.

[Guest imported_PackardV8]

It also reduces the amount of heat required if u need to use a torch under extreme rusted conditions. It's extra work to make the drill guide and use it but it IS very safe.

[34PackardRoadsta]

PV8,

Thanks tons for the info. Since I like to do as much stuff as I can, I may try this. I certainly understand the concept.

Thanks again,

Tom

[buellhall]

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[Guest imported_PackardV8]

Just drill them out to the next size Imperial or Metric and tap it. Then the only hard part is finding a head bolt. Stud and nut CAN be substituted.

Using the drill guide should do the job safely and effectively. Its just a little slow.

[Owen_Dyneto]

I know you said head bolt, but I'm assuming you mean stud? They are special threads and heat treatment, so I wouldn't advise going for an oversize thread and a harder-to-find stud. A little too much bigger and you'll end up having to drill the hole in the head for more clearance. Make the drill guide, drill it and chip it out, and if perchance you ruin the thread which you probably won't if you're careful, use a helicoil or other thread repair kit. There are many different kinds on the market.

[Rusty_OToole]

I don't like the easy outs that resemble a left hand screw thread. They wedge in too hard. I prefer the square, tapered kind. You can control how hard you tap them in.

[Guest simplyconnected]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PackardV8</div><div class="ubbcode-body">...start out with a drill bit that is about 1/2 the diameter or a little smaller than the bolt u are trying to drill out. Then progress in 1/64 or 1/32 increments until u reach a drill size about 1/32 or 1/16 less than the original tap-drill size.</div></div>This convention is the most common and the most practical.

Finding the exact center is hard for guys who don't have a whole lot of practice. Center punch, and use the smallest drill you can (without breaking it), then go up each size in small increments. Make your drill bit follow the axis of that broken stud, and use coolant on your drills. Liquid Wrench works well as a coolant, and it will help dissolve rust.

If you start small, your straight drill-hole will be your guide. Finding true center, means you can end with the largest hole possible, without damaging any threads.

Take your time. If you tire from holding things straight, stop. Take a break, and come back later. Larger EZ-out's work far better than small ones. So, drill your hole as large as you can, without drilling threads out. It's all about relieving thread stress.

Those bolts are soft in the middle, with a case hardening. You'll get there, so be patient and tenacious. That original piece will come out, and you won't need a Heli-Coil.

When you look for great quality replacement studs or bolts, check out ARP (Automotive Racing Products):

http://www.arp-bolts.com/catalog/catalog.html

ARP quote: "The threads are rolled after heat-treating, which gives them about 1000% longer fatigue life than most main bolts, which are threaded prior to heat-treating." - Dave Dare

[Restorer32]

We never, ever, use EZ-outs. We don't even have any in the shop. If you break one off you have a real problem on your hands. Progressively larger drill bits, carefully centered, is your best bet. Also be careful with heat around fragile cast iron. A properly installed Heli-Coil is at least as strong as the original threads though the starter kit is a bit pricey and you need a different kit for each size bolt.

[Matt Harwood]

If you have access to a welder, I've had a lot of success welding a nut to the broken stub and backing it out that way. You want to use a real rusty, scabby nut and get the stub as clean as possible so that the weld will really take. The heat of welding often dislodges the threads just like heating it with a torch would, but in a much more concentrated area. I've only failed once with this technique and that was simply because I couldn't get a good weld due to the location of the bolt.

I don't like EZ-outs simply because they're made of a substance that presumably fell to Earth from outer space and is harder than any known drill bit. If you break that off in there, you've really got a fight on your hands.

Edit: oops, saw someone else already suggested the welding technique.

[Guest simplyconnected]

34PackardRoadsta, your problems aren't unique. We've broken bolts, drill bits, taps, and everything else, for a very long time.

Ever notice the holes in your crankshaft? Yep, they are very long, small, and they typically start at a rod pin and end at a main bearing. Notice, too, that they enter on a hard angle and complete on an angle. The drills that make those holes break frequently (inside the crankshaft). Do we throw out a whole crank just because it has a drill bit in it? No. We use an EDM machine (Electrical Discharge Machining), to eat the drill away with a very small electric arc. Set it up, turn on the coolant water, and sit back and wait. No problem disolving EZ-Outs, drills, bolts, taps, you name it. During one shift, five or six cranks might need to be EDM'd. We machine nearly 1,000/day.

I am telling you this because nothing is disasterous. If you try, using whatever is available to you, and fail, it can still be done in a good machine shop.

Restorer32's shop doesn't have EZ-Outs. If you don't like them, that's on you. I appreciate having every helpful tool at my fingertips. EZ-outs have saved me lots of time and money, and I have NEVER broken one. They aren't brittle like a tap or a drill, they're tough. They come in lots of configurations. I have seen pipefitters make their own, to pull out broken air tool nipples on the assembly line.

By all means, try taking it out yourself. Punch the center, start with a small drill bit, and graduate to the largest hole you can in small increments. Don't drill into threads. Carry heat away with coolant, and your tools will last much longer.

When you get to the largest hole you can, an EZ-Out will help a lot. Finesse the broken piece out, using this method. Rushing will only cause frustration and more work. You will be absolutely delighted when that piece comes out. - Dave Dare

[Owen_Dyneto]

I saw a nifty little kit today in the local auto repair shop for studs and bolts broken off below the surface, I think it was made by Snap-On, not sure but it was quite old. It had a series of small end-mills for squaring up the broken end, and then a series of drill guides that get inserted down into the threaded hole above the stud. A matching drill was used to center-drill the broken piece, and then a fluted tool steel drift kind of like a reamer was driven down into the hold, and turned with a hex head. It was probably pretty pricey in its day, though one might find one at a flea market. I agree with all those who said not to use an EZ-out, if it snaps off, then you've really got a problem as they are extremely difficult to drill out.

[Phils38cpe]

A trick that I've heard of for solving the broken EZ out or tap problem is to take a Dremal tool with a little cutting wheel and cutting a ring around the shank of the tap/EZ out near the top. The cut should be deep enough so that the diameter of the shank is smaller than the "working" end of the tool. That way if you snap the tool it will break near the top thereby leaving you a stub to grab with a pliers for easy removal

[Guest Bob Call]

Tom

I have asked this question on a different site about broken exhaust manifold studs. The majority of responses I got said to weld a nut to the stud if possible. They say that the heat from the welding will loosen the threads enough so that the broken stud can be backed out while it is still warm. I had a professional engine builder tell me about the paraffin trick, but, to do this there has to be enough of the stud or bolt exposed to grip with visegrips or a pipe wrench to back it out. If there is any question in your mind about this, I would take the block to a machine shop that has a large drill press that can accurately drill 90 deg. to the block surface. Replace all of the studs and nuts, or bolts, with new ones from ARP (Automotive Racing Products) at arp-bolts.com.

Good luck

Bob

[Guest simplyconnected]

Exhaust manifold bolts are the extreme worst. The differ from head or main bolts because they see so much heat, expansion/contraction, and rust. Exhaust gasses are so hot, they pull the heat-treat right out of even the best bolts made. And they rust so bad, I have bought special sized sockets to compensate for the lost steel on the bolt heads.

Bottomed-out broken bolts are nearly as bad.

Welding a nut works. Sometimes. EZ-Outs work. Sometimes. Drilling a perfect hole, right down to the threads works, too. Sometimes. It is certainly impossible to sit here and troubleshoot with precise certainty.

In most cases, a garage mechanic can successfully extract a broken bolt. I say, use whatever means you have at your disposal. If none of that works, you can always bring it in to a good machine shop.

[Guest John_Lawrence]

Tom, I believe drilling out the broken off stud is the best way. If you do not feel comfortable doing it yourself, then a good machinist can do it for you. A Helicoil insert is a proper solution if the threads are damaged. I used a Helicoil insert for a cylinder head bolt hole in my '39 Cadillac, and it worked as advertised. I have also used left-handed drills to remove broken studs. The left-hand rotation will sometimes help loosen the stud. Good luck.

I saw your spring covers, and they look great. Colvin did a great job refinishing the fender and door on the '37. Thanks for the recommendation.

[Phils38cpe]

A quick tip for using EZ outs - grind a ring (dremel with cutoff wheel works great)around the shank of the EZ out. If and when it snaps it will break at your grind point leaving you a stub for removal.

[Guest Faust]

I agree with all said above, but would add this.

EDM around here is hyper expensive, that is due to the lack of machines.

DRILL GUIDE - Excellent solution, I do that regularly. I usually make three or four, in progressively larger sizes. As an additional safeguard in case I want to remove it I start with one that is full dimension of the bolt/stud hole. Since the hole is big enough to see down it, alignment is easier. After mounting this I insert a transfer punch and give it a tap to get an exact center hole/indent. This also makes aligning the smaller drill guide easier, with an appropriate size transfer punch you can "feel" center. Or, since they are about 6" long, you can set it in center before dropping the drill guide for tightening. If you don't have these Error Freight has them regularly for about $7.99 a set.

Machine shops. What they will do is drill to the proper size for tapping the hole. Then they will run a correct size tap in to clear the material left in the threads. If you are calling machine shops, ask if they have a magnetic base drill press. Rather than remove the block, the drill press can be mounted on the block. These are not uncommon. I almost bought one at an auction last week, I suppose I should have. As you get nearer to maximum drill out, a left hand drill may remove what is left.

If worst comes to worst, and you need a block, PM me.

[Donald_G]

I had to drill all the studs on my 1932 chrysler they needed to be removed to machine the block for rebuilding the machine shop tried their stud remover on one and broke it i made a drill jig and using a small pilot drill and the tap size drill removed all the studs no ez outs the hardest thing you will ever remove is a broken ez out

attached is a photo of the studs.

When the tap drill reached the bottom of the stud the threads were unscrewed cleanly into the waterjacket

Take your time the studs are very hard to drill use good quality drill bits

If you buy replacement studs from ARP keep in mind they have a 1/8" deep hex in the top of them for racers to install and remove them with an allen wrench this is a standard feature on all the studs they make

I purchased mine from summit racing they were made by milidon no hex on these

[Guest John_Lawrence]

Tom, I have a drill press. You are welcome to use it. I will be gone next week, but will be around through Monday. John

[Nick_S]

Holy Blast from the past Batman!!!! this thread is way old, guys! I wonder if he ever got the stud removed?