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Thread: Broken head bolt

  1. #1
    Enjoying the ride... 240ZMan's Avatar
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    Default Broken head bolt

    One of the head bolts broke last night on my "new" L28. Picture is attached. Based on other threads I've read on this site, I've been keeping it wet with penetrating oil since then. I also have drilled a hole into it to use an easy out.

    At this point I suspect the remaining bolt is rusted in the threads. The picture makes it look redder than it does in person though. I've twisted as hard as I think I should on the easy out and it's not budging. I read some discussion about heating, but I'm not sure if I should try that here, and how to go about it. I do have a propane torch (the kind used to solder copper pipe for plumbing).

    The block is on an engine stand right now so I could get it to a machine shop if necessary.

    So my questions are:

    1) should I try heating, and if so, how to go about it?

    2) what could a machine shop do that I can't?

    3) if it just wont' come out, can it be drilled out and tapped? I suppose that head bolt would be different than the the others?

    Thanks, in advance. This is so frustrating! Yesterday my new exhaust from MSA (header and 2 1/2" piping) came in, and I can't wait to get this going! Picture of header attached as well, just for a positive note
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    Daniel
    '73 240Z
    Castle Rock, CO

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    Default

    Here's the header picture. I guess I can only attach one picture per post.
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    Daniel
    '73 240Z
    Castle Rock, CO

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    Registered User Phred's Avatar
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    Default Not So Easy out

    That type of screw extractor tends to expand the part your trying to get out, so don't crank on it too much or you will split the bolt. But, I think you're in luck. The pic shows you have about three threads above the deck. I have removed many broken bolts with this method. Get a nut with the same thread as the head bolt. tighten down the nut all the way to the deck. Weld the nut down through the center, to the remaining bolt with a TIG welder. Then simply remove the nut/broken stud with the proper size socket.
    The heat from the welding process will also tend to loosen the rust bond to the block. Good luck.
    Phred

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    Default

    Thanks Phred, your suggestion is encouraging. Unfortunately TIG welding is beyond my abilities so it looks like I'm off to find a machine shop tomorrow.
    Daniel
    '73 240Z
    Castle Rock, CO

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    Registered User 1975yellowBSPZ's Avatar
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    Default Help!

    I'm dealing with the exact same problem, But I think I'm worse off.

    Heating didn't seem to help and I don't have enough salvagable threads above the deck to get a nut on. When I got the ease out to seat the bolt just refused to budge at all. I put penetrating oil in the ease out hole, which is now almost the length of the remaining bolt due to the repeated attempts to remove it. My motor is in the car and I really don't want to have to pull it out as it was a pretty big hassle getting it in there. I don't know what my options are if it won't come out tonight w/ the ease out.
    <<<<1975 280Z L28E header, flowmaster, 60mm TB, aftermarket fuel rail, custom cold air, aeromotive fuel regulator, corbeau buckets, front/rear strut bars, moto lita steering wheel, 5 point harness, 14 X 7 turbines w/ 235/60/14's, headlight covers, sidestripes, fender mount mirrors>>> SOLD AND MISSED

    Now have 2004 Subaru WRX Wagon - so is life

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    Supporting Member ChrisA's Avatar
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    Default

    Hey Daniel,

    Try heating the side of the block where the broken bolt is. And around the bolt hole. Heating the surrounding area should expand the metal a little hopefully breaking the bond between the block and the bolt. Your easy out should do the trick. Good luck.
    1973 240Z HLS30-156693

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    Registered User MikeW's Avatar
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    Default

    I've had bad luck in the past with those spiral screw extractors. If you break it off it's very hard (literally) to drill out. There are other types available. Here's one that supposedly works better. Your mileage may vary:

    http://www.sears.com/sr/javasr/produ...id=00952817000
    -Mike
    Add your Z to my online spreadsheet registry

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    Registered User inline6's Avatar
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    Default

    Another thing the machine shop could do is drill out the bolt. Basically by using a mill or precision equipment, the machine shop should be able to locate the exact center, and the drill out the center of the bolt so that just the thread of the bolt remains. Then remove the thread with a pick and or compressed air etc.

    What a pain, I'm going to clean those holes and put a drop of oil on the threads before I put the head on my new motor. I didn't realize that this was a common problem.
    Garrett

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    Default

    I tried heating but got nowhere. Even the Easy out "threads" are now damaged. Through a series of phone calls I found a shop in Denver that can disintegrate the bolt. As my engine is on a stand, I figured I would cut my losses and just take it in.

    He says they get an arc going to the bolt itself, and then immediately quench it. This thermally shocks that part of the bolt and causes it to break up into small pieces. He says they can do this without damaging the threads in the hole. I suspect there's more to it than he described, but as long as he knows how to use the tool, I'm not too worried if he can't explain how it works.

    I'm supposed to get it back tomorrow so we'll see how it goes.
    Daniel
    '73 240Z
    Castle Rock, CO

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    Registered User Gee's Avatar
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    Post same

    I had the same problem a few months ago and heat, plus an easy-out and a pair of locking pliers finally did the trick. I was told that any easy preventative measure to stop this happening in the future is to coat the threads with a smear of copper grease before putting the studs back in. I've since removed a stud that had this treatment done to it and it makes all the difference - came out without any hassles.

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    Registered User 1975yellowBSPZ's Avatar
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    Default

    did you heat the block, bolt,, or both?
    <<<<1975 280Z L28E header, flowmaster, 60mm TB, aftermarket fuel rail, custom cold air, aeromotive fuel regulator, corbeau buckets, front/rear strut bars, moto lita steering wheel, 5 point harness, 14 X 7 turbines w/ 235/60/14's, headlight covers, sidestripes, fender mount mirrors>>> SOLD AND MISSED

    Now have 2004 Subaru WRX Wagon - so is life

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    Default out?

    I heated the bolt to try to break the "seal", prior to this I used a load of penetrating oil, nearly every hour for a full day I just kept walking back out to the car and just spraying more on.. I then made sure I had the correct size easy-out as I was told this was all important. I then turned it out slowly because easy-out's are made out of toughened steel and if that broke...
    ...anyway, after getting about 1/2 cm clear of the block I gripped the end with a pair of locking pliers and turned the rest of it out - I was paranoid that the easy out would break. The hard part for me is that the b*stard broke below the level of the block and the motor was in the car at the time (as is yours). Take it slowly and it'll eventually come out.

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    Default

    Just got my block back and the broken bolt is gone. There isn't a trace I can see. I ran a stud in and it goes in smooth, and still feels tight.

    The bad news, if you can call it bad news, is that it cost $110. But in the scheme of building up a motor, I guess that isn't too bad.

    Best of luck to you, 1975yellowBSPZ. Since my block was already out of the car, I took advantage of it. I hope it doesn't get to that for you.
    Daniel
    '73 240Z
    Castle Rock, CO

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    EZ
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    Default

    Be careful not to use too much oil when reinstalling a bolt to the block/head. A few drops of oil with nowhere to go can turn into a hydraulic pump and fire through or crack a block.
    Shallow Ed's 76-280z

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    Registered User SteveK's Avatar
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    240ZMan

    What you have described sounds like "spark erosion" and has been used successfully to get many an engineer of of the poo, many moons ago (1980's) I worked for the British National Coal board, where very heavy engineering was the norm, a colleague of mine broke a 1 inch tap off in a cast iron casting which weighed half a ton and cost in excess of £10,000 - then -- boy was he glad of spark erosion.

    st0878

    Its a very good point and something to be conscious of, personal preference is to use the copper type grease's as they will stay in the threads and donít "pool" so readily

    Phred
    I did like your method M8 -- never occured to me
    Quickest NA L6 engined Z in the UK 13.19@102.02 mph for the 1/4....on a non bored/stroked 2.8

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    Default

    Great thread. I think most of us have had (or eventually will have) this problem happen to them. And once you've solved the problem using anti-sieze to prevent a future occurance is a no brainer.

    And Phil, if you can fit a nut onto the broken bolt welding it through the middle is truly a great idea. I'm almost looking forward to it happeneing again, just for the satisfaction of being able to wind that sucker out

    Cheers,

    Peter
    1972 240Z Resto almost finished
    1983 280ZX This winter's project

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    Default

    While we're on this subject, I have another question. We're fortunate in the Denver area to have a guy whose entire business is working on Zs. He has been a great source of information and advice to me. When I called him about the broken bolt, he said he didn't know as he had never broken one. At first I thought he was kidding, but he was serious. And I'd have to guess he has removed literally hundreds of heads. I broke a bolt on my second!

    So my question is what "tricks" are there to taking the head off? I think I followed everything I've read in books, but as we all know, there is a lot that isn't in books
    Daniel
    '73 240Z
    Castle Rock, CO

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