HELP - Broken head bolt
 

Hey Fellas,

Need advice to create a jig to keep my drill centered when drilling out a head bolt. Any advice/tips are appreciated. Thanks.

Chris

Pics here

https://www.jalopyjournal.com/forum/...14.587903/full
https://www.jalopyjournal.com/forum/...46.587902/full

Re: HELP - Broken head bolt
 

Engine in or out of the car???

Re: HELP - Broken head bolt
 

Out. The up close pic makes it look as if the threads are pushed into the block. They are not, but they do overlap the hole. Need to remove those threads to see the true hole.

Re: HELP - Broken head bolt
 

I can’t see your pictures on HAMB, I get an error when I click on the links.

However, I had a broken head stud in a 21 stud flathead and I thought if I made some drill guides on my friend’s lathe I would be able to get it out. Based on my experience, my advice is, don’t do it! In hindsight I wished I had welded a flat washer and nut to the broken off piece and extract it that way.

Re: HELP - Broken head bolt
 

Some rental companies have a Magnetic based Drill with a 1/2 chuck, that is what I would rent and use. I acquired a used milwaukee mag drill at a bargain buy just for this purpose to have IF needed. IF you are not adept at this and or cannot use the "weld" method like Zeke3 mentioned....I would pay a machine shop to handle it, you could cause more damage than you bargained for. JMO


AND I could not open your attached photo either

Re: HELP - Broken head bolt
 

X2 on what rockfla said.

Re: HELP - Broken head bolt
 

It looks like the bolt hole is now off center. To correct this I would use the head bolt hole in your head as a drill fixture to center line the drill bit for a 7/16 Heli coil insert. The drill bit required for the Heli coil tap is 29/64. If you open up the bolt hole in the head to the drill size you can now use the hole as a guide bushing to accurately drill the hole on center. Once that's done all you need to do is tap the hole install the Heli coil and your now all set.
Ronnieroadster

Re: HELP - Broken head bolt
 

Have your machine shop do it.

Re: HELP - Broken head bolt
 

I made a guide in the lathe that went through the head bolt hole, drilled a small hole through it, drilled the stud, then drilled the (1/2 in hole in the guide ) or just used the head for the heilocoil bit, then tap it.

Re: HELP - Broken head bolt
 

I have drilled out more than a few broken studs
The way I center the drill: center punch the end of the stud.
Use a 3/16" bit, hand held drill. Stop often, check to see if it looks OK.
Correct by angling the drill, sometimes a lot.
Follow with a little larger bit. Then a larger one.
When you get to the sides of the hole that's the block threads, stop.
Use angle sharpened punches, pick out the remnants of the stud.

I like the weld the washer to the stud, then the nut technique,
just have not used it yet.

Karl

Re: HELP - Broken head bolt
 

You could try a quick temporary farmer's fix by tapping the hole for a 3/8 coarse or fine thread stud (not bolt since hole isn't centered & probably not straight). Slip the head on. And not torque the nut more than about 30-35 ft-lbs. I've done this before on a daily driver. Never gave me a problem except for thinking about it. So it ended up being a permanent farmer's fix until I traded the car in about 5 years later. 8^)

Re: HELP - Broken head bolt
 

Ronnie is absolutely correct, a very good plan.



Terry

Re: HELP - Broken head bolt
 

Too easy. If it goes into water jacket drill 1/8th hole or bigger and blow out with cutting torch. It will not even get threads in block hot. Run a tap or better yet a thread chaser. Wash block and get on down the highway. Too easy.

Re: HELP - Broken head bolt
 

I would only use heli coil as a last resort. Whatever way you go, you still have to center the hole.
Get a small roller bearing with a 12mm OD. Drill the head hole from the gasket side until the bearing sits below the surface, then use that as a guide. Fit the head and use the biggest drill that will go through the bearing ID and drill it. Plenty of WD-40. Try an easy -out first. If that fails just keep increasing the drill size until you just break through the root of the thread. Use a small screw driver or scriber to pick the thread out.

Re: HELP - Broken head bolt
 

I don't have a lot of experience with the hot wrench, so I was not brave enough to use Kiwi's method above. I tried using the torch to heat the bolt after I had drilled a large hole through the middle of it, thinking the fastener would shrink and loosen after it cooled. That didn't work.

I made drill guides out of 1/2" bolts turned down to 0.466" diameter and used left hand drill bits thinking the drill bits would catch and unscrew the remaining threads. That didn't work either.

I was not crazy about using the cylinder head as a fixture for drilling using my guides because the head can move around a couple of thousandths of an inch in all directions, so you have to try to center it up.

I finally decided to try welding a washer, or any flat piece of steel, and nut on. I only have a 110v mig to weld with and was thinking it would not be up to the job. The other problem was that there wasn't much left of the stud beyond the threads stuck in the block to weld to. I wish I had tried welding the washer and nut on sooner.

Anyway, I got about a thread and a half out with welding the washer and nut on. I then switched to my Blue Point screw extracting splines and was able to remove the remains of the broken off head stud without totally destroying the threads in the block.

Ps: My son said let the machine shop do it and the deeper I got into it, I knew he was right.

Re: HELP - Broken head bolt
 

Hello Zeke; I've welder a flat washer with a smaller ID than the OD of the stud to the stud and then centered a nut on the washer and welded the nut to the washer. The heat of welding actually causes the stud to loosen a little as long as you wait until all is completely cooled off before you try to remove it. If you don't weld I've waisted a lot of space, Craig.

Re: HELP - Broken head bolt
 

This works like a charm!!!

Re: HELP - Broken head bolt
 

deuce5window: Your idea seems very doable as shown in video below. Thanks for mentioning it.

Here's an excellent video showing and telling how it's done plus the theory of minimal heat dissipation into the surrounding metal.
https://www.bing.com/videos/search?q...E6C8&FORM=VIRE

I would suggest drilling and tapping a practice piece in a chuck of cast iron to master the technique and get the feel of the process. Not all the bolt holes in a flathead block are "through holes". Some are blind and bottom out. So create practice pieces using both thru and blind holes.

Re: HELP - Broken head bolt
 

Thanks Craig, I will do that next time.

Re: HELP - Broken head bolt
 

I heat them red hot first and let them cool. I use a Snap-On stud remover with a collet designed for that thread, tightened as tight as I can get it. Then I let a 1/2" impact "lightly" hammer on it to break the bond loose. A breaker bar and socket will just twist and break them. You want that light hammering too loosen them. It's not a good feeling when the very first one breaks. 45 of them came right out and three broke.

Then I mig weld nuts to the broken ones. Grind the plating off the nuts and washers or buy un-plated ones. The plating contaminates the weld, and it won't be as strong. We did this at work a lot on the trucks and we found we had better luck by removing the plating. Two of them came out by welding nuts to them and one refused to move I broke several of the welded nuts off. As you can see it's hard to get the mig wire down in there that deep to get good penetration on the stud so first what I do is weld a thick washer to the stud and then weld the nut to the washer, filling the entire void in the nut with weld so that heat will travel down into the threads. Then let it cool before trying to remove. The mig weld will not stick to the cast iron, no worry of messing up the block. Not everybody has a mig welder so that leaves the drill. You can see how the coolant (actually lack of the green stuff) got around the stud and the electrolysis and corrosion ate the block. It also glued that stud to the block.

I just got a call and need to leave but I will post more photos of the welded studs and the drill guide bushing I use to take out the one stud. Oops! I forgot to comeback yesterday.

You can see its wet around the base of the half-out stud. It started to come out and stopped and wouldn't budge. I heated it and melted some wax which wicked down into the threads and then came right out. You can see that the mig weld did not stick or damage the block and I'm not that good of a welder. Infact I'm a one-eyed welder after Lasic surgery destroyed my left cornea, they cut too deep. I had to have a transplant and now I can't see anything out of that eye. I can see, I just can't see the eye chart, not the letters the fricking chart. It's all about taking your time and being patient with this stuff. Slow is faster in the long run.

The bushing is from a Snap-On extractor set. It has all kinds of bushings, bits and extractors. Bolt the head on, drop the bushing in there and it's impossible to not drill the center of the stud. I removed the head and drilled it with two more "sharp" bits leaving just a shell of the stud and it came right. I finally bought one of those Drill Doctor bit sharpeners, it works pretty good.