Remove a rounded out Allen bolt

[mangeldbug]

I had a baaaadly broken bolt experience this weekend.  Everyone read and check this bolt!  You do NOT want to have to go through what I went through.  Very nerve racking experience.

I was replacing engine bolts with stainless steel ones and I removed the oil passage bolt in the head (by the spark plug). It had a copper washer and had green crusty stuff all around it. I cleaned that off but not finding a SS bolt of similar length, I reinstalled the original. SNAP! right at the shoulder. I didnt even snug it down! Once I pried the bolt head off the allen I was using, I saw that the bolt was completely rotten. It was light colored, brittle looking, and had what looked like metal crystals flaking away inside the allen head hole.

My husband had recently bought left handed drill bits, so this should be no problem...ha. He tried those, easy outs, even picks and pliers to pry out the pieces. Every time the bolt would start to turn, it would immediately strip or crumble because it was so soft and rotted out. The bolt just kept shattering. There was talk of removing the head and taking it to someone. After 3 hours of fighting with it, as a last ditch effort Ryan removed the cam cover just above the rotten bolt. We found the other oil passage hole, so he took his air compressor and shot some high pressure air through there and out the bolt hole - which actually worked! Little pieces of metal shot out all over the garage. The threads were pretty messed up, but at least it was now free from debris. He chased the threads with his drill and tap set and installed an extra SS bolt from the engine bolt kit - amazingly no leaks. We put the original copper washer back on.

I ran this scenario by LT at Desmo Times and he said that bolt is prone to moisture rot.  Any moisture caught in the head tries to escape via that bolt.  He suggests using Permatex on the threads to prevent any future moisture corrosion.

[scott_araujo]

My first attacks are always:
1) penetrating oil
2) whack it with a hammer, maybe using a punch
3) apply a little heat to the area around the bolt

These apply whether it's an allen, screw, or hex bolt.

An easy and non-destructive way to get some more grip on an allen is to get a thin smear of grease on the wrench and then dip it into some fine sand or grit, or use something like rubbing or polishing compound.  The grit fills in the gap between the wrench and stretched hole a little and also give you the bite you need to turn it.  One of the advantages is that if all this goes wrong it usually hasn't done any more damage.

If that fails I usually cut a slot for a large screwdriver or flats for a wrench using a Dremel.

Scott

[brimo]

# 1 is use a good quality set of allen keys as cheap ones aren't made all that accurately and are a bit soft themselves.
Cut a slot with your dremel or hacksaw and use a hand impact driver.
http://www.dansmc.com/stripbolt.htm

[Monstermash]

Here is a much less sophisticated method for removing allen head bolts if they aren't too destroyed.

Take the allen wrench/key that fits the bolt and dip the end in motor oil. Then dip the end into some fine sand. Yes, I said sand like you find on the gound. Then use it as normal. The sand will provide a nice gripping surface on the inside of the stripped allen head and will also take up the space between the tool and the bolt.

 I have done this a few times and it works great.

[whaler]

Here is a much less sophisticated method for removing allen head bolts if they aren't too destroyed.

Take the allen wrench/key that fits the bolt and dip the end in motor oil. Then dip the end into some fine sand. Yes, I said sand like you find on the gound. Then use it as normal. The sand will provide a nice gripping surface on the inside of the stripped allen head and will also take up the space between the tool and the bolt.

 I have done this a few times and it works great.

+1! I have used this trick before, and it does work.

Another method I have used for a bolt that had been broke off flush is that I use a center punch right in the middle of the broked off bolt body. Give it a couple of good whacks, not only to properly locate your hole, but also to shock the threads a little. Then I used a left handed drill bit (cuts in counter clockwise direction), I go real slow, and use a lot of pressure. As soon at that bit hogs in, the bolt breaks free and usually spins right out.

Just my 2 cents....

[Monstermash]

+1! I have used this trick before, and it does work.

Another method I have used for a bolt that had been broke off flush is that I use a center punch right in the middle of the broked off bolt body. Give it a couple of good whacks, not only to properly locate your hole, but also to shock the threads a little. Then I used a left handed drill bit (cuts in counter clockwise direction), I go real slow, and use a lot of pressure. As soon at that bit hogs in, the bolt breaks free and usually spins right out.

Just my 2 cents....

 There is a tool called an "easy out" that is basically the same thing.

[whaler]

There is a tool called an "easy out" that is basically the same thing.

I've never liked easy outs. Mostly because they are tapered, and when trying to remove the fastner, they apply pressure outwards, pushing the threads against the very hole your trying to get the bolt out of. With the LH drill bit, your using the cutting force of the bit to dig into the end of the fastner and twist it out.

[Shortie]

A couple other ways my beau and I have used:

If the bolt is soft enough, with enough of a head left on it you can sometimes mash a set of vise grips on it nice and tight and turn it out.

Also - air chisel! Definietly not ideal, but we've had to do it and it works. Make sure you have a steady hand and wear ear plugs!

[TCK!]

I just had one of these this week and I used a Torx head to get it out. It worked well.

[bdfinally]

Saw a mechanic use a hardened socket this morning on a stripped out allen. He found one a little smaller than the head, set it on top of it with an extension in it and tapped it 2 or 3 times with a brass mallet, put a rachet on it  and putting most of his body weight on it that baby came right out.

[Slide Panda]

Take the allen wrench/key that fits the bolt and dip the end in motor oil. Then dip the end into some fine sand. Yes, I said sand like you find on the gound. Then use it as normal. The sand will provide a nice gripping surface on the inside of the stripped allen head and will also take up the space between the tool and the bolt.

Similar idea is to use valve griding compound.  They to specifically make some goop for this job too - but it's like 5x the costs of valve compound.

And if you check in the very 1st of the How To threads - I started one for hard to find tools.  In it there's a link for left hand drill bits.