Busted engine head bolt removal?

[kevin king]

Anyone here know how to remove this busted engine head bolt? Or know the size of bolt it is? It a k&b stallion 35.

[Dan McEntee]

  The main thing you have to hope for is that the screw isn't bottomed out in the hole, like some one replaced the stock screw with one just a bit longer. To start, go through several cycles of heating the area up and letting it cool, and hitting it with some penetrating oil now and then, just to break loose any oxidation or corrosion in the threads. File a flap spot on what it left of the screw, and see if you can get even a slight center punch mark dead center on the screw. Then drill a hole with a drill that is about 3/4 the size of the screw. I'm guessing it's a 4-40, maybe a 5-40. Drill the hole about 1/4" deep or so. Now take an old Allen wrench that is a bit bigger than the hole, and grind a shallow taper on the short end, and then try to get it square shaped with 4 square corners. You just made yourself an easy out. If you don't have any scrap Allen wrenches, use an appropriate piece of music wire ground to the same square shape with a taper that will fit the hole. Then just try tapping the modified end into the hole until it get tight. If it bottoms out in the hole, drill it a bit deeper or grind just a bit of the end off the tapered end. Then warm up the case again and try some torque and see what happens. I'm guessing that the screw is bottomed out in the hole, and that is why it broke off that close to the cylinder surface. If the rest of the engine is good, just look for a parts engine with a good case if you can't get the screw out.
  Type at you later,
   Dan McEntee

[Air Ministry .]

HEAT . C R C . HEAT C R C . HEAT . C R C . Tap a 1/10th notch , Oz inches . Very little . But nevertheless . a tap to free . It should then turn . YOUR BEST NO WOBBLE PLIERS , or razor saw ( mask the case )
AND get in a screw slot WHILST holding in DeVice . ( Just one lug ) . the HEAT & Turn . with 110 % of your attention on ' Its toining ' .

Discusing it , while glancing over your shoulder , untill its non - adverse and then talk of cooperation and rewards , how much better it will be , if its not obstinant itll be able to run again . Speak clearly . No yelling . !

[redout]

If you try the drilling with a left hand drill bit sometimes the cutting forces will wind the screw out. If I was trying this, I would prepare the broken off screw as Dan said and make sure you securely hold the crankcase squarely ( screw in line with the drill bit ) and of course do it in a drill press or a mill.

[Dan McEntee]

If you try the drilling with a left hand drill bit sometimes the cutting forces will wind the screw out. If I was trying this, I would prepare the broken off screw as Dan said and make sure you securely hold the crankcase squarely ( screw in line with the drill bit ) and of course do it in a drill press or a mill.

   I didn't bring up the left hand drill bit because 1) It sounds like I'm making a joke! Like "I need a left handed Crescent wrench!" There really is such a thing and I have a set left over from my working days as a maintenance technician. 2) They can be hard to find. I have even gone into industrial supply places looking for them and get really funny looks! In the right situation they are the cat's pajamas! But I don't think you will easily find a left handed drill bit as small as Kevin needs.

    If the home made easy out doesn't work, then the second option is to drill all the way down, and if still centered well enough, drill with the tap size drill for the screw, the chase the debris out with a bottoming tap.

  Keep us posted.
  Dan McEntee

[Tim Wescott]

   I didn't bring up the left hand drill bit because 1) It sounds like I'm making a joke! Like "I need a left handed Crescent wrench!" There really is such a thing and I have a set left over from my working days as a maintenance technician. 2) They can be hard to find. I have even gone into industrial supply places looking for them and get really funny looks! In the right situation they are the cat's pajamas! But I don't think you will easily find a left handed drill bit as small as Kevin needs.

Mail-order saves the day:

Like the devil, McMaster-Carr has anything you want -- for a price.  Including left handed drill bits small enough for the job.  MSC Direct also has them.

[Tim Wescott]

I'd try two things before I tried Dan's suggestion -- but I may end up shooting myself in the foot if I did.

In all cases, do the heat, penetrant, cool, repeat cycle several times (Aero Croil is great for this, if you can get it).  Then I would, first, try to gently grip the screw stub with a pair of needle-nose pliers and see if it's loose enough to start moving.  If so -- out comes the screw.  If not -- stop before you make things worse.  Then, if I have a thin enough Dremel Dangerous Disk and if I could do it without cutting into the head, I'd cut a slot in the top of the screw and try taking it out with a screwdriver.  Use your judgement and care -- your situation is yours, not mine, so my advise may not apply.

Then I'd try Dan's suggestion.

If I was absolutely positively sure that the case was aluminum, I'd try dissolving the screw with alumina.  I've never actually done this so I may be passing on crap advise, but my understanding is that alumina and water will dissolve steel, but not touch aluminum.  If I reached this point -- because I've never tried it -- I'd try it out on a piece of scrap aluminum, or I'd try a bit of the stuff on some part of that valuable case that doesn't matter, like the very corner of a mounting ear or something.

[Dick Byron]

Take a pencil with an eraser on it and use the eraser end to turn it out.
Works for me.

[Dennis Toth]

Kevin,
You need to heat the case with a heat gun on high, if there is enough of the bolt sticking out after the case is hot you might be able to grab it with lockjaw pliers or do what Dick suggested and get it out. If all else fails you can then go the drill out method.

Best,   DennisT

[Brett Buck]

I would go very easy on drilling methods, unless you tried everything else first. It's very tricky to drill down the center of a 4-40 or other small screw , and if it goes out the side you are going to ruin the case. I would do everything (heat and Knock 'er' Loose or whatever), then try to spin it out by hand, with an eraser, and if necessary, cut a screw slot using a Dremel cut-off wheel, even if you have to cut into the case a little. That is less damaging than getting off-center with a drill.

     If you absolutely have to drill it, for certain, you need to put it into a vertical mill, mill the remaining end off flat, center and dimple it with the smallest center or spotting drill and then drill with a left-hand drill with decent pressure to try to get it to grab and spin out. The problem is that will be a *tiny* drill - Assuming it is 4-40, a tap drill is a #43, you would want to start with maybe a #46 or $47 to cover yourself against getting off-center. That's only 79 thousandths of an inch and extremely prone to deflecting or breaking under the required pressure to get it to "bite" and spin the screw out. At least, cut if off or chuck it up with only about 1/2" protruding to keep the deflection down. If you do end up drilling it out instead of spinning, if you are even a little bit off-center, you are in real trouble because you will never get it centered up again and a few thousandths of an inch means you can't go all the way to the tap drill. Then, you have to try to get a pick to pull up the ends of the threads into a .080 diameter hole.

   I think drilling it out completely will come to grief. Worst-case you have to drill it clear and use a heli-coil or keensert. It looks like you have enough meat around it to do that. So trying to machine it out would be my very last choice.

     Brett

[Brett Buck]

If and only if all else fails, toss it. The Stallion was a CHEAP engine that was supposed to compete with the McCoy red heads, a 4.95 engine when a Fox cost 9.95. It's only function is nostalgia.

    True, but you are not allowing for the OCD and pathological perfectionism of model airplane people. You can't just let something go if it is at all salvagable, and with enough effort, anything is salvageable.

   For example, I have so far spent two hours and $14 on fixing a 25-year old $40 digital watch - and I have something like 5 other watches, all much better. If I had even a little sense, I would just toss it an move on. But, after cleaning all the contacts, it still doesn't work quite right and will not hold a charge, , so I figure all it will take is a new supercap/"rechargable battery" , so I have one on the way and also the necessary tweezers to get it the latch on the battery off. Because I can't help myself. Another example, I have my dad's old 35mm camera -draggy shutter, need a CLA. I send it off, the guy says he needs a new part, so I got another identical camera (for cheap) to harvest the parts. Got the first one fixed - and now I am looking for some spare parts for the *parts camera*, because I can't just junk that one out, either!  I would note that both of then are nearly worthless for collectors and barely usable - and I have at least 5 other much better 35mm cameras that I woudl use before this one.

DSM-V 300.3

     Brett

[john e. holliday]

I my self have had an engine some one broke the screw/bolt off using too much muscle.   I used the thinnest dremel cut off disc I had and cut a slot so that if I cut into the case it would not hurt the sealor edge of cylinder.   A small screw driver finished the work.  K&B's use 4-40 threads.

[MikeyPratt]

I buy up and repair old McCoys all the time, you never know what the people that ownedc them were thinking or doing lol.  To remove broken screws grind of as close to flush at the top of the case, then using a Dremel small cut off disk and cut a slot in the broken bolt about 1/32” deep and get a high quality flat blade screw driver that fits into the slot. Heat the aluminum case and spray with penetrating oil and allow it cool completely (do this a few times if you want).  Place the case in the freezer so the steel bolt contracts overnight, this hearting and freezing the bolt helps loosen it slightly.

Place the case lightly in a vise and apply penetrating oil, with the screwdriver inserted in the slot rap the screwdriver with a small hammer to break the bolt free.  Try turning the bolt out, if it come out great if it only turns a little that’s great also, turn in back and spray with penetrant again, it may be a slow go but it’s starting to work.  Repeats until it’s removed.  I know this takes some time but it’s really not that hard to do.  Another note on this, a helicoil works well also if needed.

Mikey

[Dennis Adamisin]

    True, but you are not allowing for the OCD and pathological perfectionism of model airplane people. You can't just let something go if it is at all salvagable, and with enough effort, anything is salvageable.

     Brett

+1 spoken like a true controliner!

[Ken Culbertson]

Never mind - just go read Mikey's post again.

Ken

[Phil Spillman]

Heat treat and let cool. Cut a small grove in the bolt with a jeweler's saw. a backed Xacto saw, back out with a small jewerer's screw driver!

Phil Spillman

[Dan McEntee]

    True, but you are not allowing for the OCD and pathological perfectionism of model airplane people. You can't just let something go if it is at all salvagable, and with enough effort, anything is salvageable.

     Brett

      We fix things because we can! I fixed things for a living, sometimes because there was no other option. Things that ranged from something that weighed a few grams, to things that who the hell knows how heavy it was!!  I wear a certain style of Timex watch and have been wearing them for years and years. The watch cases are plastic and break down from sweat, heat, chemicals and stress. I have a plastic bag that I have accumulated the carcasses in for years, and have built watches from the parts several times. When the cases break down and there is no where to attach the wrist band, I formed brackets that accept the ends of the Twist-O-Flex band and solder that to the back cover. When I manage to save one, it saves me 30 to 40 bucks. I might only have an hour or so into the process. I learn and figure other stuff out along the way also. The watch I have on my wrist right now is the first one, of the same style as all the others, in almost 30 years, that will need a new battery before any of the other parts on it break!

   Type at you later,
   Dan McEntee

[Air Ministry .]

Spark Errosion'd probly only cost a hundred bucks . 



 

[RC Storick]

Okay, I didn't want to weigh in but I will. If I had that here I would just take a 6-32 nut set it on top of the bolt and a quick spot weld on top of it and turn it out. 5-minute fix

[Gerald Arana]

[quote author=MikeyPratt link=topic=62436.msg645203#msg645203

Place the case in a vise and apply penetrating oil, with the screwdriver inserted in the slot rap the screwdriver with a small hammer to break the bolt free.  Try turning the bolt out, if it come out great if it only turns a little that’s great also, turn in back and spray with penetrant again, it may be a slow go but it’s starting to work.  Repeats until it’s removed.  I know this takes some time but it’s really not that hard to do.  Another note on this, a helicoil works well also if needed.

Mikey
[/quote]

Mikey,

NEVER EVER put an engine in a vice. Get an OAK board and cut it out fit fit the engine and mount the engine in it....with the mounting lugs. Yes all four bolts.

Then extract the bolt per the other guys suggestions.

Good luck, Jerry


PS: Don't ask me how I know to NOT put an engine in the vice. 

PPS: I like Roberts spot weld answer best!

[Ken Culbertson]

Okay, I didn't want to weigh in but I will. If I had that here I would just take a 6-32 nut set it on top of the bolt and a quick spot weld on top of it and turn it out. 5-minute fix

Not so great if you don't have a spot welder.  But, it is still the best solution so far short of tossing it.

Ken 

[kevin king]

Thank you everyone for your help. I will pass this info along to Jose, a new comer to CL who is just starting out. I appreciate it!

Kevin King

[Doug Moon]

Okay, I didn't want to weigh in but I will. If I had that here I would just take a 6-32 nut set it on top of the bolt and a quick spot weld on top of it and turn it out. 5-minute fix

This!

[Dan McEntee]

Okay, I didn't want to weigh in but I will. If I had that here I would just take a 6-32 nut set it on top of the bolt and a quick spot weld on top of it and turn it out. 5-minute fix

   This is far, far easier said than done, even on bolts larger than this. That is why I usually use other techniques on broken bolts. Reaching down inside that tiny 6-32 nut just impedes all your vision of the target. Not much easier on a 1/2-13 bolt. I think Tim's idea of dissolving the screw in alumina has some merit. After he mentioned it I remember watch a short video on it some where, but can't find it again.

  Type at you later,
    Dan McEntee

[Ken Culbertson]

https://chemistry.stackexchange.com/questions/9819/how-to-dissolve-steel-without-affecting-aluminium-alloy

You might want to read this before dipping the case in anything.  I have no dog in this fight, but I found the conversation worth the reading.  Other methods here seem to be validated.  Our problem is size.  It is a 4-40.  Most googled solutions are for much bigger stuff.

Ken

[kevin king]

Although I cant remember the specifics, this problem reminded me of the time my leadhand at Boeing walked in to our area with a pail of liquid nitrogen(?) He was either trying to install or remove a bolt, or bushing.

[Lauri Malila]

Nitric acid. L

[Doug Moon]

I had a Allen Head bolt stuck in the aluminum transmission case on my 96 corvette. It is the fill plug. It's a standard so I am thinking it hasn't ever been removed until now, 25 years. It was stuck and I mean really stuck. If I tried to turn it but the giant Allen head socket would start to strip out on the inside. Not good. I tried PB blaster and some other solvents and nothing seemed to work. I tried some heat. That didn't work. Then I went to youtube looking at solvents.

Liquid wrench sold at Lowes caught my eye. I watched some guy do a test on several brands and it was one of the best and releasing stuck bolts.

I got a can and read the directions and this is what happened.
On a Saturday morning about 9am I applied liquid wrench to the plug. All over it and on the tiny bit of thread that was exposed. I applied again at 12pm. I applied again at 5pm. I never tried to loosen during this time. The next day I applied it at 9am. Around 12pm that day I wanted to try it. Plug came out of there with total ease. Probably less than 20lbs of torque to get it out. The directions say 1 3 hour application should be fine. But I didn't want to damage that plug as they aren't readily available. So I gave it a whole day and kept reapplying. I am sold on the stuff and the directions.

Keep soaking it with liquid wrench every 3 hours for a day then grip the bolt with some small vise grips and it should come out.   

[Doug Moon]

Thank you everyone for your help. I will pass this info along to Jose, a new comer to CL who is just starting out. I appreciate it!

Kevin King

It would be best if he can afford a newer engine to go that route. He will have more fun flying with newer stuff.

[Gordon Tarbell]

Use the heat up and let it cool method , once hot drip "Aero Kroil" as already mentioned on to it and let it cool . In 50yrs of Machine shop work it is the best penetrating liquid out there that I have used and I think I have used them all . The second best is a 50/50 mix of dexron II and acetone.  the only difference between the two would be the oil of winter green found in Aero Kroil.  The heat expands the Alu more than the steel fastener and the penetrating fluid has an easier path to work down the threads. Multiple cycles of this method will win out as long as your patience does not. 

[Brent Williams]

It would be best if he can afford a newer engine to go that route. He will have more fun flying with newer stuff.

Best answer! 

[Air Ministry .]

Okay, I didn't want to weigh in but I will. If I had that here I would just take a 6-32 nut set it on top of the bolt and a quick spot weld on top of it and turn it out. 5-minute fix

A BRAZEing entusiast could get it , too . The Heat would free it off while you were at it . Not a amature job . foist class suggestion ,  .

[GERALD WIMMER]

Hello I recently had the same problem of a broken bolt on a K&B 45 Greenhead that my brother wanted me to save, being a tidy control line case . Slotted the broken stub and heated the case a few times and soaked with ATF a number of times . It came out quite easy in the end as there was no pressure/tension on the broken bolt or rusty cylinder sleeve holding onto it (why it broke in the first place when my brother tried to disassemble it). Sparky's weld on solution works well and I have done this many times when restoring WWII vehicles for a living years ago, but it may be hard to weld onto such a small area.

Regards Gerald

[John Gluth]

Thank you everyone for your help. I will pass this info along to Jose, a new comer to CL who is just starting out. I appreciate it!

Kevin King

30 replies. Was the bolt remnant removed?

[Doug Moisuk]

I don’t know if enyone has suggested this. Engine cases are aluminum. Bolts are hardened steel. The bolt can be dissolved out. This goes away back in my memory. I think it was nitric acid. But do some checking on this. That case maybe a different metal mix. Old guy memory. I’ll check with a couple guys.

[Doug Moisuk]

Ok her is the latest from my friends about using Nitric acid.

Hi Doug,
Yes can use 20% nitric acid to oxidize the head bolt. Use silicone to build up a small cup structure around the bolt so can act as a reservoir for the acid solution. It should begin bubbling as the process occurs and warming the case will speed things up. Occasionally should remove the older acid and replace with fresh.

Rod

The 20% nitric acid treatment only works if it is a high carbon content bolt. If stainless steel or other will not work.
Rod

[Doug Moisuk]

And it is important to use 20-25% acid and not concentrated acid. When diluting acid it is alphabetical ie a to w, you add acid to water slowly with stirring.

[Gerald Arana]

And it is important to use 20-25% acid and not concentrated acid. When diluting acid it is alphabetical ie a to w, you add acid to water slowly with stirring.

My chemistry teacher said "Do as you otter, add the acid to the water".

And that was in '58.........

Cheers, Jerry

[john e. holliday]

Has the bolt been removed yet?

[kevin king]

Has the bolt been removed yet?

John, i dont think it has been removed. I posted this question for a new club member that want to know how to replace the bolt. I have directed him to this thread  numerous times now.  I appreciate all the the suggestions. If he gets the bolt removed i will let you know. But i wouldnt hold my breath.

[Scott Richlen]

Ummm, not knowing  any better, I bought a K&B Stallion 35 many years ago.  I built a beautiful Carl Goldberg Shoestring to put it on.  What an awful thing to do to a Shoestring stunter.  I have no fond memories of that boat anchor piece of crap engine!

Instead of spending a lot of time trying to extract that screw, just order a new one from Masters-Carr.  What is it - maybe  a 5-40?

[Ken Culbertson]

Ummm, not knowing  any better, I bought a K&B Stallion 35 many years ago.  I built a beautiful Carl Goldberg Shoestring to put it on.  What an awful thing to do to a Shoestring stunter.  I have no fond memories of that boat anchor piece of crap engine!

  Same experience!  A "boat anchor piece of crap" is what the good ones were.!  Replaced mine with a McCoy and had a ball with the Shoestring.  They are forgiving.

Ken

[John Gluth]

Sounds like Scott knows the screws, really are worth more than the Stallion 35. 

[Scott Richlen]

A "boat anchor piece of crap" is what the good ones were. 

Yep.  I mark it up as a "learning experience"

  the screws, really are worth more than the Stallion 35. 

Yep, I shoulda bought a McCoy....or a Fox....or an Enya....or a.....etc....

                say....how did those Camerons run?