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Topic: Broken Bolts (Read 793 times) previous topic - next topic

Broken Bolts

I have a question for you guys with machinist backgrounds. I broke off the two bolts on the bracket that attaches the fuel solenoid to the engine. (those bolts are used to attach the bracket for my air throttle linkage) The bolts are marked TVS 9.8 which I believe corresponds to our grade 5. They are about 1/4" in diameter and the head takes a 7mm socket. Anyhow, my plan is to use a spring loaded center punch, followed by a center drill, followed by a couple of left handed bits, followed by an easy out. I'm hitting them now with penetrating oil. I have to do this with the bracket in the photo attached as I don't want to chance breaking the third bolt that holds it on.

In the past I have had mixed results with easy outs. I am terrified of breaking them off. I would like to buy good quality tools but just what I need. i.e. the correct center punch and center drill and drill bits rather than sets. I've got easy outs but I'm not sure of their quality. I'm looking for recommendations. Thanks.
jor

Re: Broken Bolts

Reply #1 –
Good penetrating oil for a couple of days.

Drill, then heat around it.

Light, sharp raps on the punch to loosen it.

Then easy out.

Re: Broken Bolts

Reply #2 –
Try warming them up a little when you apply your penetrating oil, and a lot of patience.

Re: Broken Bolts

Reply #3 –
Got it. Still looking for recommendations on the tools.
jor

Re: Broken Bolts

Reply #4 –
How far recessed is the bolt in the bracket? Makes a difference on what tool to use for an easy out.

Re: Broken Bolts

Reply #5 –
First drill a small hole right though the bolt and  then add penetratingly oil though the bolt
hole. That way you get penetrating oil from both ends. The left hand drill bits are great.
Taping and heat can be helpful. The longer you have is better for the penetrating oil to
work. Easy out are great but they only work so so. If all else fails the bolt can be drill to the
inside of the threads and tap out the rest.

Re: Broken Bolts

Reply #6 –
Quote
How far recessed is the bolt in the bracket?

Just the thickness of the bracket. Probably about 1/4" plate.
jor

Re: Broken Bolts

Reply #7 –
Quote
First drill a small hole right though the bolt and  then add penetratingly oil though the bolt
hole.

It's a blind hole not a through hole. Re drilling and tapping, that's one of my questions. If a 9.8 is similar to a grade 5 what kind of drill bit should I use. I want to buy a quality bit.
jor

Re: Broken Bolts

Reply #8 –
Quote from: oldguy –
If all else fails the bolt can be drill to the inside of the threads and tap out the rest.
And, if you bugger up the threads too bad you can always drill the hole oversize and use a Heli-Coil threaded insert.

Has saved the A$$ of many amateur mechanics (not that I would know anything about that...).

Re: Broken Bolts

Reply #9 –
The bolt shouldn't be right to the end so when you drill right though the bolt
there is a nice pocket for the penetratingly oil to do its work. Even grade 8 bolts
a cheep dill bit will drill but that being said get a good bits and left handed drill
bits when used some times screws the bolt out.

Re: Broken Bolts

Reply #10 –
So sorry to read you have some broken bolts.  It happened to me as well, and it was a drill and it out to the largest bit we risked using, and then using the easy out, and then some picks to remove anything left over.  Then cleaned with a tap.

Re: Broken Bolts

Reply #11 –

Don't use the spiral easyouts as they spread the bolt and make it harder to get out. I couldn't find the shouldered easyouts I have online but this is better than the spiral type.

Amazon.com: Lisle 62900 Extractor Set: Automotive

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Re: Broken Bolts

Reply #12 –

I personally like to strike the end of the bolt since it is extended out quite firmly. When it was tightened up it was pulling on half the threads. By striking it you will move to the other side of the threads and in doing so have moved the seized bolt. Not much but it has moved. Kroil or mouse milk are my personal preferred favorite penetrating oils. Mark center and drill a 1/8" #30 drill thru center as mentioned to access other side . Propane torch is your friend. I also have been using freeze spray and a spray tube in the middle with additional luck. Reverse drills are real nice if you can find them. Multiple heat cycles always help wake things up. Welding a washer on the end really works well then a nut on the washer. Primarily because of the isolated heat cycles. Repeat several time and they always come out. So there are several different styles of easy outs. Good ones  cost more and fail equally. My go to favorite are straight flute snap on/ridgid easy outs. Drill the pilot hole thru the fastener then drive straight in and with adapter supplied with it work till motion is achieved. I've learned if you feel them crack you can stop and remove them before they shear off. I've drilled sheared ones and that a terrible story very slow. Heat cycles and penetrating oil is your friend. If while removing it stops rotating you stop also and rotate it back in. May take multiple cycles. If you drill hole out of center into threads it will key the two together. IMO this is not the place to learn how to master removing fasteners and failure can become expensive. Out of reach is a additional multipler to failure. Yes generally one can oversized and install a helicoil which is stronger than original cut threads. Don't make a bad job a horrible one. Honestly I personally hate taking over a buggered up attempt that actually only made it worse. I've personally seen engines removed because there was no approved repair available once butchered up. If it's within your skill set go for it, if not find someone who has the skills. The extra spent may way outweigh the final cost.
Good luck Scott
RIDGID 35585 10 Screw Extractor Set, 1/4-inch to 1/2-inch Broken Screw...
All the little round tubs are drill guides to find center without looking at it.
Also I've really become a fan of these little battery operated impactors for Corroded fasteners

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Re: Broken Bolts

Reply #13 –
Quote from: jor –
It's a blind hole not a through hole. Re drilling and tapping, that's one of my questions. If a 9.8 is similar to a grade 5 what kind of drill bit should I use. I want to buy a quality bit.
jor
MSCDirect.

High Speed Steel, left hand cut.  Slowest gear on your cordless drill.  Speed is not your friend.

Metric hint: tap drill size is bolt size minus the thread pitch.  M8X1.5? 6.5mm tap drill. 

https://www.mscdirect.com/browse/tn/Holemaking/Drilling-Drill-Bits/Metalworking-Multipurpose-Drill-Bits/Screw-Machine-Length-Drill-Bits?navid=12106190#navid=12106190+4288217000+4287517978+4288218594+4287060125

Re: Broken Bolts

Reply #14 –
If you can remove the bracket around the broken bolts, you can weld nut on the ends and the heat may help the rotation of the bolts.

Re: Broken Bolts

Reply #15 –
Fastenal stores have pretty good drill bits,or try your local Snapon or Matco tool man,meet him at one of his stops.

Re: Broken Bolts

Reply #16 –
Center punch then start drilling.  Use cutting oil.  Keep increasing drill bit size till you can back it out with easy out or other means or it falls into pieces you can extract.  Probably have to retap to clean the threads or go up a size, even SAE since it will now be American.  If you are not fluent in drilling steel you might want to investigate bit speed. 

Re: Broken Bolts

Reply #17 –
Thanks to all. This is great advice. I've removed a number of broke bolts over the years but then I've also broke off a couple of drill bits. I could remove the bracket for better access but I am reticent to do so because, if that one snaps, I'd be in real trouble as it would be impossible to get out.

I've got a set of those flute type as well as spiral but I'm going to buy new. Thinking about whether to go with craneman's fluted or dsd's set. I think I'll buy the bits from ot's link but we do have a Festenal in town. I have Kroil. Never heard of freezer spray and I'm ordering a can. I've always done the "strike the bolt" technique and will do so here also.

Anyhow, thanks to everyone for your excellent advice. Fortunately (?) I'm working on another project right now (cutting the rust out of a 54 Ford) so I can think of something else besides this damn Foretravel!  ;D  ;D
jor

Re: Broken Bolts

Reply #18 –
CRC Freeze Off.  I used it several times with engine warm ups between.  Twenty-three year old exhaust manifold bolts on my U320, and all twelve came out with no issues!

Re: Broken Bolts

Reply #19 –
You might soak that remaining bolt in penetrating oil for a day or so and then apply only well-under breaking torque to see if you can remove it. 

Penetrating oil and light sharp raps on a bolt head often loosen them up.

And, if you do get it to start turning at all, continue with penetrating oil working it out, then in just a little, back out..............