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"...and then the bolt extractor broke off"


Jerry_75_Guy

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Jerry_75_Guy

Well, they say the wages of sin are death, so I suppose the wages of inexperience and stupidity are often $$$$ and frustration.

 

Upon removing the head cover prior to the valve adj., one of the cyl. head attach bolt tips sheared off in the head. "Well," says I, "I'll just borrow a friends extractor kit, buy a new bolt, and once again, all will be right with the world!" fool that I am.

 

I gingerly drilled into the broken bolt tip, not far, maybe 1/4". Lined up the matching extractor, slowly and gently began screwing the extractor into the new hole, and "tink" the end of the extractor snaps off in the new hole....Sigh....And I really was being slow and gentle, as the tools belonged to a friend, and I was paranoid in general since I'd never done this before. Given the lack of force at the time, I can only guess the extractor was fatigued from use, but I really don't know, and at this point I guess it doesn't matter.

 

I tried to use the next larger two drill bits in the set to bore into the extractor, but being hardened steel I had no luck. I've called two dealers, and they both said they weren't sure but thought I'd have to pull the head and have the whole thing machined out. If at all possible, I'd really like to avoid that.

 

Is there anything I can do to salvage this situation? Am I truely screwed?

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I would start with lots of WD-40 or some other penetrating type oil, let it soak in for a while (perhaps overnight even) then apply some heat using a heat guy or even a torch if you can, do my favorite god pleasing rain dance and then try to back it out using a small flat bladed screwdriver and a dremel (sp?) type tool to cut a slot into the remaining parts (done prior to applying the heat of course)....

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Don't feel bad. In 45+ years of mechanical work I have yet to see a screw extractor work like it is supposed to. They always break off and leave an impossibly hard element in the center that complicates further steps. They only offer the hope, and never the reality of a fix.

 

Personally I have had the best luck with heat, a small prick punch and a very light hammer.

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No_Twilight

Well, I'm not sure how much metal there is there where your bolt is broken off but if you can get a dremmel or other grinder into there you can grind out the broken off hardened extracter. Once you do that you can probably drill out the broken-off steel stud. BTW, forget about getting it out w/o grinding and or drilling because it was stuck in there hard enough to break off the bolt in the first place. The most important thing to keep in mind as drilling it out is to keep your hole centered on the original location. Once you get that drilled out you will now have a hole of undetermined size. If it is small enough you can just tap it for a helicoil and be done. But if it is too big for that you can just drill and tap it with any convenient metric or SAE tap. Then send me your final dimensions with a small amount of cash and I'll make you a custom ss adapter in my machine shop. You'll thread in my adapter and it will have threads in the middle for your valve cover bolt.

 

PM me if you need my help,

Jerry

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Jerry_75_Guy

Jerry; thanks, I may take you up on that if I can get the bolt out tongue.gif

 

Chad; sadly there's no bolt sticking out to 'grab' with the Sears device.

 

Update: despite help from a friend, we couldn't manage to drill into the broken off extractor ( man is that thing is hard !)

 

Head removal and subsequent machining may be necessary bncry.gif

 

I'm tempted to just get an appropriately sized nut and bolt to seal the head cover bolt hole and use a little high temp silicone to act as a gasket so at least the RT is rideable and I don't miss the Vermont rally frown.gif

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Slyder_Steve

You will not have any luck attempting to drill out the extractor--they're just too hard for drills. If you want to fix this yourself, get yourself a carbide "burr" type grinding bit. They're not too expensive from the hardware store. If you've got a dremil tool, get one that fits in that. You need one that's "about" the same size as the extractor you broke off--got to keep enough meat from the bolt to ensure no damage to the parent metal. Use very slight pressure and use a 1 second on, 2 second off kind of motion. This will make sure the carbide doesn't overheat. (okay the carbide won't overheat, but the silver solder will if it gets too hot). Once you break through the extractor, fish out the remaining pieces, and give it another go--with a square type extractor if you can get one. Worst case is you'll end up having to have a plug made to fit the hole.

 

My 2 cents based on 15-plus years as a machinist. Best of luck.

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If mechanical extraction does not work, visit a skilled welder.

 

I believe extractions can be made using EDM procedures or, you can TIG a piece onto the broken bolt and out it comes. Don't forget to heat everything up to allow the best success.

 

And, when reinstalling the valve cover bolts, only 8-9 Nm.

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I did exactly the same thing, but to the (oops!) cylinder head of a FRIEND'S car!

 

What I did was to buy a cheap carbide concrete drill that was somewhat smaller than the size of the extractor. Then I carefully started drilling, ensuring the drill was centered (this was the hard part, and sharpening the carbide spade tip with a grinder -a bit laborious-- helps a lot).

 

Once the extractor was drilled a few mm down the center, I went in with a VERY slightly oversize steel drill, which tended to jam in there as it rotated. It jammed and "grabbed" the end of the extractor and (because the extractor is left-hand threaded) it spun the extractor right out.

 

After the extractor was out, I carefully drilled out the remaining bolt. This also requires care, because the surrounding aluminum is soft and the drill tends to wander. Drilling a small pilot hole is very helpful.

 

Finally once the bolt was drilled out, I drilled into the alminum with the correct size drill for a HeliCoil tap, then tapped the hole and inserted a Helicoil.

 

The whole thing took only an hour or so.

 

Bob.

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i too have had that happen. is it possible to use a very small drill and dril in several places right against the edge of the hole? if you can get it relieved, it will come out. another odd option would be to use a carbide tipped spring type cetner punch, you may be able to reverse twist the extractor. don't be overly concerned about ruining the hole. if you are carefull and only mar on edge you can drop a helicoil in it.

 

big pita always when that happens.

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If the extractor is only about a 1/4" deep you might be able to break it up. A small chisel might do the trick.

 

The extractor is hard and brittle, that's why it broke. It's not very deep, you should be able to break it up.

 

OR you could use a very small grinding tool and grind away...

 

But you need to stay inside the original bolt . IF you don't think you can do that...take off the head and get some help.

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photojournalyst

I'm just curious, since this is a fairly stupid question, but don't you have to have the cover off to get the head off? I don't think there are many options for head removal except for taking off the valve cover, and then unscrewing the head.

 

Don't mean to be a pessimist here, I'm just want to know what I'm missing.

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Removing the cylinder head to perform the extraction is NOT a big deal. It does require some metric tools and a torque wrench during reassembly. However, the extraction will be easier and more successful if the head is free.

 

Also, you'll be able to inspect your cylinder walls in that particular cylinder.

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There may be flying metal - remember your eye protection.

Funny about that warning. It is appropriate in this case, but I have to laugh that nearly everthng you buy these days has "Warning - wear eye protection" on it. I have screwdrivers, pliers, and even a socket set that has this warning on it. This warning is so overused, it has become utterly meaningless. Too bad for the times it really would be useful! Reminds me of the story about the little boy crying "Wolf"!

 

Bob.

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John Dickens
Don't feel bad. In 45+ years of mechanical work I have yet to see a screw extractor work like it is supposed to. They always break off and leave an impossibly hard element in the center that complicates further steps. They only offer the hope, and never the reality of a fix.

 

Too right. The screw type are tapered so as you screw them in they expand the broken bolt tighter into the threads.

 

The only type I have ever got to work are the square type with 4 cutting edges.You hammer them into the bolt. They also have a slight taper but don't seem to distort the bolt like the spiral thread extractors.

 

boltextractors.gif

 

My father used to use the tang of an old file to do the same job.

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Eckhard Grohe

The most elegant and surest way is to remove the head and EDM( Electro Discharge Machining) out the broken screw extractor and the broken screw. A moderately skilled operator would not touch the head at all and be able to pull out the remaining bolt material in the grooves.

 

Good luck on your repair.

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A mechanic of the "old school" who used to work on my bike NEVER used extractors. He always used left hand threaded taps. He said that they were less inclined to snap off.

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You may not be brave enough to do this, but it works.

Because the ez out is very hard you will NEVER drill it out but if you take a cutting torch and heat it up it will turn molten long before you head and you can remove it with a very quick blast from the torch. I have done this. Sure, I was nervous, but is was not my head I was working on.

Good luck.

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Isatis_4CH92

Hello,

 

I know it doesn't help much but the same happened to me too. Ruined a complete Sunday afternoon (also a car cylinderhead).

 

Trying to cure this puts you on the slipery slope where you have 70% chance to make even more damage.

 

Need a lot of Zen and clear thoughts. After the end of the episode, I tried to think it over again and studied very attentively this kind of extractor. It's pure sh**t and I am 200% with nrp and John Dickens

 

Don't feel bad. In 45+ years of mechanical work I have yet to see a screw extractor work like it is supposed to. They always break off and leave an impossibly hard element in the center that complicates further steps. They only offer the hope, and never the reality of a fix.

 

Too right. The screw type are tapered so as you screw them in they expand the broken bolt tighter into the threads.

 

The only type I have ever got to work are the square type with 4 cutting edges.You hammer them into the bolt. They also have a slight taper but don't seem to distort the bolt like the spiral thread extractors.

 

My father used to use the tang of an old file to do the same job.

 

Another alternative is to grind a triangular section with a slight slope into a broken off threading tool (not sure I am clear)

 

Then do the same: hit it into the piece to be extracted and turn. The triangle seems to distort less the bolt.

 

And before you come to use the rest of the threaded spiral extractors, throw them far far away wave.gif You won't be sorry

 

Stay cool,

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BucksTherapy

My vote would be to have another bolt welded onto the first. A mig or tig will work. The weld will only take to the steel bolt and not the aluminum head. Care needs to be taken not to overheat and melt the aluminum but this is not that difficult. I have done this before successfully.

 

Whether you decide to use a sharp point punch to try to drive it out or you eld something onto it I would heat the area first. Heat it as hot as you are comfortable it won't harm the finish or worse yet melt the aluminum.

 

This should be a 5 minute job for someone with a welder.

 

I am left wondering why it was so hard to come out in the first place.

 

Good Luck.

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