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Unsticking Factory tapping in old radiator

If your worried about a cast or steel plug and the drill slipping off, can ya not just re-drill & tap another hole next to it?


  • chris_69
    chris_69 Member Posts: 29
    Unsticking Factory tapping in old radiator

    I'd like to reuse an old cast-iron radiator that was pulled out of a hot water system in a one-pipe steam system, which of course means plugging the upper inlet and adding an air vent.

    Is there any hope of getting the factory plug out of the air vent tapping? It looks like an ordinary screw head. Big fittings came off with a long wrench and a swift kick. No way I can get enough torque on this with any imaginable screwdriver; if I just put a pipe wrench on the handle of a screwdriver it'll simply tear the head of the screw apart.

    D'ya think the plug is steel rather than cast iron? Can I just drill into it?
  • chris_69
    chris_69 Member Posts: 29
    The flat area for tapping is pretty small

    there is a small flat area that has the original factory tapping -- I would guess the cast iron is a little thicker there. Either side of that I'd be into the curved part of the radiator column.
  • bob young
    bob young Member Posts: 2,177

    Drill & Tap with exact size matching tools stanard procedure
  • What about,,,,,,,

    The other column? Can you get into the center of-it there? It may not be "bossed" for this, but the hole is only 1/8" anyway so you should be able-to.
  • Robert O'Connor_12
    Robert O'Connor_12 Member Posts: 728
    plug removal

    I have found that even if little of the bleed plug is sticking out (you really don't need much) you can remove it by grabing it with the edge of a tiny pipe wrench. You still must remove the paint, spray it with a quality liquid wrench type of product and try shocking it a bit by tapping it firmly with the screw driver in the slot (impact driver works, but be very careful). Heating the area around it never hurts either. Other wise, drill it, and use an easy-out.

    Good Luck!

    Robert O'Connor/NJ
  • Timco
    Timco Member Posts: 3,040

    I had a machine shop here pull out an old plug, and they welded a nut over the plug to the top of it. The heat from the weld added to the torque of a nut did the trick!

    Just a guy running some pipes.
  • John N
    John N Member Posts: 15
    You can get

    most anything that's rusted in place-including plugs (small or large) in old radiators. I've done it many times, and never had a problem. You'll need an oxy-acetylene torch for this to get it hot enough, and a big wrench that won't slip and round off the plug. Just heat all around the plug until it's nearly red hot. You'll have to be careful here not to crack the cast iron. The idea is to expand the metal around the plug enough so it will move. It's likely you don't have the torch, so take the rad to your local auto repair shop. They should be willing to help you out. For the small ones with the slotted screw driver-type head, use an impact screw driver with the torch. I've even been lucky enough a couple times with just that and liquid wrench, but it took several days of soaking with the LW, and a lot of patience with the impact driver.
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