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Thread: Softening exhaust bolts for drilling out?

  1. #1
    Join Date
    Nov 2001
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    SE Cheesehead land, WI
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    563

    Default Softening exhaust bolts for drilling out?

    My old beater '92 Ranger is so close to hitting the half-million-mile mark (currently at 490,000) that I owe it to the old girl to get the exhaust back to a tolerable noise level.

    The y-pipe coming of the exhaust manifold is toast. And there was no way to remove the bolts holding this y-pipe to the manifold, they were there 19yrs in a northern climate with lots of road salt, tough winters, and never in a garage.

    So I had to chisel, cut, and grind off the bolts (or studs?) holding that y-pipe onto the manifold. With 19yrs and countless heat/cool cycles- man, those things were TOUGH. So now I'm getting ready to take on the dreaded task of drilling out the remaining portions of the left in the maniolds so I can bolt on a new y-pipe.

    My question- is there any way to 'soften' these incredibly tough bolts before attempting to drill them out? All I have is a MAP gas torch (and propane), but wondering if heating them until red color and then letting them cool will soften them up a bit?

    Or any other advice for this undesirable job?

  2. #2
    Dr Stan Guest

    Default

    Is the manifold still mounted on the engine and in the engine compartment?

    If not I'd set it up in a vert mill (or drill press) and heat the broken stud/bolt and center drill it while it is still hot. I did this numerous times on steam valves while I was in the Navy. I doubt if you'll do much in the way of softening it since it will quickly cool due to the heat transfer to the manifold.

  3. #3
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    Apr 2010
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    Spotsylvania, VA
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    but wondering if heating them until red color and then letting them cool will soften them up a bit
    I believe that could have the opposite affect.

  4. #4
    Join Date
    Nov 2001
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    SE Cheesehead land, WI
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    The manifolds are still on the engine block. I do NOT want to remove the manifolds from the block. If I attempt those manifold bolts in the block, I know I'll end up snapping several of those off too, and then I'll have an even bigger mess.

    This is a 4.0L six cyl engine in that little Ranger, so it is quite tight around there. If I were to snap off a manifold bolt in the engine block, I'd have to pull the entire engine to fix that.... At this point in her life, that is more trouble than it is worth.

    So I'm working on these manifold-to-pipe bolts with the manifolds mounted, and I have the truck up on jack stands working from below. Big fun.
    Last edited by T.Hoffman; 05-19-2011 at 08:58 AM.

  5. #5
    Join Date
    Nov 2001
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    SE Cheesehead land, WI
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    Default

    Quote Originally Posted by flathead4
    I believe that could have the opposite affect.
    I was told by someone with questionable knowledge level about this on the heating the bolts to red to soften them thing.

    I don't know enough about hardening/softening metal, and that's why I thought this forum would know more about that than most.

    The knowledge on this board is phenomenal, I lurk a lot and really enjoy the reading.
    Last edited by T.Hoffman; 05-19-2011 at 08:58 AM.

  6. #6
    Join Date
    Sep 2008
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    2,155

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    T, I have removed quite a few of those things in vehicles of different types and what I usually do is just heat the manifold itself where the stud screws into it, heat it until red hot and then let it cool. Do that several times, heat and then allow to cool but DON'T try to remove the stud while the manifold stud boss is still red hot as this can damage the threads in the manifold. Most of the time after a few heat/cool cycles and a squirt of your favorite penetrating oil the studs will screw right out without problem. Sure beats trying to drill them out!

  7. #7
    Join Date
    Nov 2001
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    SE Cheesehead land, WI
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    Unfortunately at this point there is nothing left to "grab" to try to unscrew the remaining portion left in the manifold. After 19yrs in that vehicle, I couldn't even identify a hex head of a bolt up there- it was just a ball of rusted/welded goo. No room to get a vise grips on the side to attemp to unscrew, anything that was going to be done has to be performed on axis from below the manifold. I had a helluva time just getting the old y-pipe off. That's where I had to chisel, cut, and grind through some little side openings after I removed the tires and wheel wells.

    I was thinking about getting some left hand drills and maybe have a little bit of luck attempting to drill them out that they might unscrew at some point?

    I'm not worried about goobering up any threads in the manifold. I just want to plow a hole through there so I can bolt up the new y-pipe with a through-bolt and nut.
    Last edited by T.Hoffman; 05-19-2011 at 09:11 AM.

  8. #8
    Join Date
    May 2006
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    north bay area
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    Wow, that is a bunch of miles!!!

    Know a guy who welded studs onto his, but doubt if that,s a pratical solution to this.

  9. #9
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    yup, I'm the original owner. 19yrs ago I got out of college, got a new job, and needed a vehicle to replace my barely running piece-o-crap station wagon.

    That little Ranger has been, and will always be, the best running vehicle I will ever own. There has been so little I have had to do to it over the years outside of normal maintenance (tires, brakes, belts, battery, plugs, exhaust, fluids, etc).

    Over 19yrs I've replaced:
    Starter, power steering pump, alternator, ECU, front coil spring mount, radius arm and bushings. My first clutch lasted 395,000 until the transmission died. I bought a used trans off Ebay and installed that myself.
    As long as I had everything apart I put in a new clutch and slave cylinder. I still had around 30% life left on the original clutch!

    I'd say I got my money's worth out of Old Blue. She has never left me stranded, anywhere. That's why I owe it to her for an exhaust for that last 10k miles to hit 500,000.
    Last edited by T.Hoffman; 05-19-2011 at 09:23 AM.

  10. #10
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    Mar 2005
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    Albuquerque, New Mexico USA
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    What I used to do was to find a hex nut that just about fit over the nub, then welded it to the nub and backed the nub out with a wrench over the nut. It would almost always come out on the first try if I got it stuck on OK. This would even work on those that broke a little way under the surface if you could stuck a rod in and build it up a bit first as the weld would never stick to the cast iron.

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