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Thread: Removing corroded Pipe Nipple

  1. #1
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    Default Removing corroded Pipe Nipple

    This isn't exactly boat related, but I didn't want to put it in the bilge.

    I have a 5.7 litre Chevrolet engine. The heater return hose connects into the top of the intake manifold. The connection is basically a 1/2" pipe nipple. It corroded and broke off essentially flush with the top of the manifold. Any ideas on how to get the remainder of the nipple out of the manifold?

    Since the nipple corrorded and broke off, I doubt if the remaining piece is all too solid.

    I have been working on this engine for weeks and I finally got it running and this happened. I sure hope there is a way out other than replacing the manifold.

    Thanks
    Alan Peck

  2. #2
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    Try to saw a slot as if you were cutting the pipe lengthwise, from the inside out. (Try a sawzall blade held in some vise grips).Stop before you cut into the threads. Or if you have a drill the right size, drill it just shy of the threads. Using a punch or cold chisel try to tap the broken stub inwards. If you can get a corner started keep working it in until something gives. It might be better to remove the manifold and do it on the bench. Run a tap through when you get it cleaned out.

  3. #3
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    There's a tool you can get at the plumbers supply or hardware store for this purpose. Basically it screws into the nipple counter clockwise to try to unscrew it and will have no chance of messing up the threads. I had the same thing happen on my heat exchanger from a corroded brass elbow.
    Will

  4. #4
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    There is also a plumber's tool called an internal pipe wrench. Looks like a little cam shaft with teeth and a hex head. Put it in the fitting and turn it with a wrench. The teeth grip the inside of the fitting and allow you to spin it out. Just a few dollars at any hardware store.
    Bill R

    There was supposed to be an earth shattering KABOOM!

  5. #5
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    Cut inside slots !!!! just did one that way yesterday ....
    Last edited by George Ray; 06-12-2007 at 10:28 AM.

  6. #6
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    I wouldn't buy anything. If it's sufficiently frozen to twist off the fitting then it isn't likely any Easyout'll free it.

    Grind a hacksaw blade to fit and cut it as has been suggested. Then you'll need a pipe tap in the correct size to chase all the rust out of the threads before reinstallation. The manifold will have to come off to do a proper job. Any of that hard rust falling inside won't help your bearing life.
    Last edited by Bob Smalser; 06-11-2007 at 10:02 PM.

  7. #7
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    Thanks for the ideas. I am going to try a spiral pipe extractor first. If that doesn't work I'll try the slot idea.

    If none of that works, does anyone have any ideas on how I can just plug the hole and forget about a working heater? The hole is basically the ID of 1/2" pipe or around 3/8 to 1/2" plus or minus.

    Alan
    Alan Peck

  8. #8

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    Quote Originally Posted by Alan View Post
    If none of that works, does anyone have any ideas on how I can just plug the hole and forget about a working heater?
    Don't go that route. Cast iron GM manifolds are cheap and plentiful and they take a couple of hours to swap giving the added benefit of all new no-leak gaskets. Take advantage of the situation and replace your rocker cover gaskets at the same time and paint them (and the manifold) before you put it all together.

    Rob

  9. #9
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    Spiral Extractors make a thin walled piece expand and bind even tighter. Not a good thing. The idea is to find a way to reduce the binding resistance, either expand the outer piece with heat or slot the inner piece and then when turning the thin metal left at the bottom of the slots crushes/bends a bit ( it only takes a tiny bit ) and the part loosens and turns.

    Spiral extractors are seldom a good thing, the fluted extractors are a better bet as they have less tendency to force/expand the parts and make them fit together even tighter.

  10. #10
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    Default Progress Report

    Thanks again everyone for the ideas. I spent a couple of hours working on it this evening and I think? I am making some progress.

    I tried a spiral extraction tool, but the material left in the hole was badly corroded and had no strength. However, by working it around for a while it removed a lot of the old nipple wall thickness.

    Next I used various cold chisels to carefully remove as much as I could down to the top of the threads in the manifold. Then I used a motodrill with a small grinding wheel and took of as much as I dared with the goal of just getting to the top of the threads.

    Tomorrow I am going out to buy a plumbing pipe tap and try to clean out the threads. I sure hope it works.

    I'll keep you posted.
    Alan Peck

  11. #11
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    Get something with a hard sharp point and clean out the first few threads before you try tapping. A pointy punch or even the point of a divider might work. Just so the tap starts correctly. The danger here being starting to cut an entirely new set of threads.Use a lot of oil or WD-40. When you start the tap use a lot of feel and do it real slow.If you're not feeling thread engagement right away I'd back off and clean it out some more.

  12. #12
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    It was really difficult to acheive engagement with the existing threads. However, with patience I think I ended up with a fair set of threads, not perfect, but they may work. I have hooked everything up and I see no immediate leaks. A little time will tell more.

    Thanks everyone for all the good advice, I used most all of it.

    Alan
    Alan Peck

  13. #13
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    What I have done is to heat up broken pipes red hot with a torch this expands the metal and cracks the rust crystals.

    Then I have used a screw driver and hammer and collapsed the fitting inwards and it pops right out.
    Sometimes done it with it very hot so the metal is softer.

    I have also cut the down to the threads with a hacksaw blade to make the screw driver or chisel and hammer trick work better.

  14. #14
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    Heating the broken pipe sounds like a good idea. Is there any concern about the heat damaging the surrounding cast iron?
    Alan Peck

  15. #15
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    I'd be real careful there. If you get the metal red hot you could easily crack the iron and then you'd really have a problem. It's one thing to heat some pipe fittings and quite another to heat an iron manifold.

  16. #16
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    no, it wont hurt the cast iron part to heat it with a torch.
    If your cast iron manifold was cracked, you would have to get it red hot to braze it.

    I have an oxy-acetylene torch.

    In this case, you would mostly just heat the inner wall of the broken fitting selectively with the torch.

    Even a propane torch is better than nothing.

  17. #17
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    I can't tell you how many nipple threads I removed from well pumps and pressure tanks using the hacksaw blade holder and caving it inwards as described above. Once you get the cut to the threads,a center punch and a hammer will cave it in even if just a enough to grab the caved in part with needlenose pliars which will shrink it the rest of the way enough to nearly fall out. After you get the part out,if there is a slight score in the threads,teflon tape will correct it. Sometimes you have to cut it in two places.

  18. #18
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    +1 for cutting.
    Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  19. #19
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    Quote Originally Posted by sdowney717 View Post
    no, it wont hurt the cast iron part to heat it with a torch.
    If your cast iron manifold was cracked, you would have to get it red hot to braze it.

    I have an oxy-acetylene torch.

    In this case, you would mostly just heat the inner wall of the broken fitting selectively with the torch.

    Even a propane torch is better than nothing.
    In the case of pipe nipples,most likely they used a thread sealer such as rectorseal on plumbing stuff. The heat will reliquify/soften what is in the threads and will aid in the part's removal. Sometimes it is just old,dried out pipe dope that is holding the part from turning. Whenever removing old plumbing fittings,it is best to heat them anyway to not only get them out easier,but to keep yourself from turning red and crushing the nipple with the wrench. Crushing/flexing the pipe out of round will also make it bind and seem frozen.
    Last edited by pipefitter; 06-19-2007 at 01:08 AM.

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