Broken Bolt Help

92 GMC C1500 V6

What started out as a simple tranny fluid change has become over a week of my truck on ramps.

I’ve got a bolt that had an extractor in it and the extractor broke off, drilled through the extractor but now its so uneven I’ve began to get off the bolt (will probably have to be tapped now). Any one know of a way to get the bolt flush and even for drilling?

Clean everything and put a new gasket on the pan, replace all the other bolts and snug them evenly, then tighten them in a stages. If the pan doesn’t leak at the broken bolt leave it alone. If it does leak put put valve cover bolt wings (any good parts counter man know what they are) on the 2 adjacent bolts and again hope for the best. But unless it is a constant drizzle the truck is driveable until you repair the bolt, Just be very careful to avoid breaking the transmission flange. A drip from a missing bolt is preferable to a stream pouring from a gap in the case.

And extractors are not easily drilled out. My only answer to a broken extractor (easy out) has been welding a bolt onto the stub and twisting it out while heating the housing. Not a good idea on an installed transmission.

Whatever you do avoid breaking the housing.


Do you have a fairly powerful air compressor at home?

Perhaps you could remove the pan, and VERY CAREFULLY use a very small diegrinder tip to get that bolt flush. Then you can centerpunch it, and attempt to drill and extract it.

BTW . . . I 've had pretty good luck extracting broken bolts with left handed drill bits

I recently had to helicoil the transmission case on my brother’s car. The bolts didn’t break on me, but the threads got so darn worn out over time, that I couldn’t properly torque 3 of the bolts, resulting in a major leak. After the repair, all is well again. I was able to torque all of the bolts and there are no more atf leaks.

All I can say is, do whatever you must, and don’t be scared.

@Red Knox the extractor is out, doubting the leak will stop because the bolts are almost in line (corner then two bolts down is next broken).

@db4690 no compressor. Would not be able to get left handed bits until first paycheck at new job.

Any one ever try grind stones with dremel?

you know a good welder or steel fabricator? if the end of the broken bolt is pretty much flush w the housing, youmay be able to weld a bolt with an end preparedfor a full penetration weld, to the broken end. let it cool a bit and the seized bolt should release. unfortunately, the stuff broken off in the broken bolt may prevent you from making a sound weld. which you will need. but maybe not. oh and don’t damage the housing! piece of cake. oh yeah, don t start a fire.

but it may not even leak with one loose bolt, as a previous poster suggested

…and if it does you may be able to attach a small clamp to the loose spot,

With one loose bolt it MIGHT be fine. On my Dodge Minivan, an enthusiastic kids who just started working in the shop, stripped on of the transmission pan bolts. (Was going right at them with the air gun, when I stopped him, he was surprised and said “I always do it this way”; spoke to the boss and turned out by “always” he meant the week and a half he had been there).
We moved and since I have space to work on my cars, I did all the next pan drops and always would tighten this bolt snug and it would be fine. Until 3 weeks ago (one week after the last pan drop), the thing opened and flooded the floor with ATF. Had to take it to a shop to helicoil it.

Listen to the experts but I had to weld a nut on a water pump bolt to get it out once. Even with a wire feed and a little bit of the bolt sticking out, its not easy to do. Then if you are laying under the truck, trying to hold the nut in place and tack weld around an aluminum housing, I dunno.

I’m not clear if you have a piece of the bolt sticking out or not. If so I’d just try and grab on with a needle nose vice grip or something. The bolt can’t be in there that tight unless they really cross threaded it. If you got the old easy out out already, I’d be tempted just to try and use another one, maybe the next size up and work it out. You’re gonna have to re-tap that hole though no matter what or use the heli coil, but I think you should try and avoid totally drilling it out. Start with a small bit then a larger one. Good luck.

yeah, not easy ay all , and if you had enough bolt sticking out, you may want simply weld a nut on the end to extract the bolt. the process I described was more for replacing a broken stud.
really not a piece of cake, and any mistakes can ruin all sorts of stuff. sorry.

Is it an aluminum head? I am going to do some experiments but found this interesting enough to try for broken iron nuts in aluminum dock post sleeve.
Submerge the offending part into a pyrex dish (you don’t want to do this in a steel pot!!!) full of a solution of 4tbsp alum to 1 cup water (as much as you need to completely cover the bolt hole), I then placed the pyrex dish into a pot full of nearly boiling water and let it go. Heat is ESSENTIAL, or the alum won’t dissolve. You’ll see the steel part start to bubble a little bit (it’s letting off pure oxygen) as the alum goes to town.
alum (potassium aluminum sulfate).
Evidently this food additive for pickles will dissolve ferrous metal but not aluminum.
You wil probably not be able to drill through the extractor. Tig welding a nut or wrench is the best but I do not have one and am dubious about standing in the water if I did.

If you do get the broken bolt out and the threads in the tranny are too stripped to hold I have had good luck with using a hacksawed bolt or threaded rod to make a stud, putting some JB Weld up in the hole threading the stud up into the hole and letting dry overnight. Makes it easier to put your tranny pan back on too.

Remember, there’s always the local machine shop. Shade tree mechanics break off extractors all the time. Machine shops have special drill bits that can remove a broken off extractor. The way they work as I understand, I’ve never seen one, but I think they are like a miniature hole saw, they drill in a circle around the extractor in the soft surrounding metal, then the extractor is removed with the surrounding plug. The ideas above sound like fun to try if you’ve got plenty of time to experiment, but if you are in a hurry to get this over and done, maybe a visit to your local auto machine shop is the better path.

If the extractor is broken off inside the bolt, you can’t drill into the extractor. It’s hardened steel.

The only way to get the extractor/broken bolt out is to weld a nut on the inside to extractor/broken bolt.

Know anybody with a MIG welder?


As I read it, Harland (I hope that’s not my cousin with the problem), is changing his transmission fluid, so the truck is up on ramps and he’s working overhead on it. He can’t really take it to the machine shop at this point or immerse it in a solution.

any luck Harland?

Without knowing how far along this problem has gotten, I might suggest the following.
Maybe a short length of 1/2" angle or even a thicker flat (steel or aluminum) just long enough to reach from one good bolt to another as a support for the pan might allow the broken bolt to remain there without causing any leaks.

Much like the old small block Chevys way back when that used the valve cover stiffener strips to prevent leaks between the mounting bolts.

That is what Rod Nox suggested in the first reply.

@Tester, good post, just curious. I have absolutely no welding experience. A welding neophyte am I. I can see how your idea would-- in theory – make it possible to remove the stuck bolt/extractor, but how would you weld a nut to the extractor/bolt without also welding it to the surrounding metal? Is there a welding trick/technique for accomplishing such a thing?