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Stuck brass plug


Richard F
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I have an 8 cyl Auburn with a brass water drain plug in the block that is pretty well stuck. (7/16 male square head pipe thread). I've tried penetrating oil and tapping it but all I seem to do is begin to round off the corners.

Anyone have any tricks to try ? Will a bit of heat from a propane torch free up a brass plug or only expand it? Ever hear of a square female socket?

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I've never seen a square socket, but they do make 8 point sockets that work quite well on square nuts and bolts. I got some at Sears.

It sounds like heat is the next thing to try, but someone else may have a better idea. I'd be careful though. You could make it worse. I know you're trying to get this plug out of a cast iron block, but as a cautionary note for others who might face a similar situation with a rediator or cooling system component, be careful. Lots of times, the flange for the drain plug on a radiator or cooling system pipe is soldered in place. Too much heat may make the whole thing come off. Then you get a lesson in sweat soldering! <img src="http://www.aaca.org/ubbthreads/images/graemlins/shocked.gif" alt="" />

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Hi, Yes they make square sockets. Snap On has them, as do the other better brands of tools. When you heat up a stuck bolt or screw, the reason it comes out is the heat vaporises the rust and thus the threads start to turn. You can heat the block up if you are careful but the problem is that the plug has a pipe tap taper and is stuck due to the taper. I would recommend you let someone with experience try it. Lots of practice and the right touch is the best choice. Ed

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my thought would be to extend your leverage with a long iron pipe over the end of your new wrench while adding heat with a torch of some sort. be careful, dont force it, once it starts it will come out easily the trick is to get it started without breaking it off at which point the above drilling out becomes necessary. If drilling it out make sure to vacuum out all the metal bits so they don't get sucked up into the motor oil passages (ouch).

Shawn

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Heat the brass plug red hot, not the block this will expand the plug to the point that when you let it cool it will now have shrunk smaller and be able to be removed easy. Let it cool naturally, and it will comeout, then run a NPT tap to clean up the hole, you might find some square or 8 point sockets at home depot as well..

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Thanks for the advice. The plug goes to the water jacket not the oil sump so I am not as worried about vacuuming--will flush out the jacket with water later. It was an 8 point socket, and later various crescents and compression wrenches that rounded off the fitting--I never could find a 4-point socket, not even Snapon had one. No room for a pipe extension on the wrench.

I'm going to try the following, in order:

1) Heat the plug to very hot, and let it cool as suggested. If this fails:

2) Drill the center out, tap with a left-hand tap, insert a left-hand bolt and see if a 6-point socket will remove it. If the bolt pulls up the threads, I'll try a bolt extractor in the hole;

3) Last resort: Drill the whole thing out oversize, tap it and use a larger plug.

--Richard Floch

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You're making it too complicated. Heat it up and take it out while still hot. Careful though, if you get brass too hot it will crumble under the force of your wrench. Then the only alternative will be to drill and tap. A pipe wrench should do the trick. A propane torch might not give you the rapid heating you need. An oxy-acetylene torch and a big wrench works for me every time.

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Richard , What year Auburn? years ago my father and I made new coachwork for the 7th Auburn Boattail made (1928). The understanding I have is that the frist 25 boattail's the coachwork was made by a cabinet maker locally and had extras not on any other models, Dual golf club doors and dual side mounts.

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Hello Richard:

Please save drilling oversize as last resort, most likely the casting has a "Boss" build up for this plug location. Drilling oversize might exceed the optimum wall available for the plug tap thread size. Make your worst case drill out the brass material until just where you see cast iron then chase the threads with a good NPT tap. Stude8

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Albert

It's not a boattail, it's a 34 phaeton 8 cylinder--that happens to have a blown head gasket at the moment. That's why I am trying to drain the block. Still haven't gotten that plug out. I have broken two extractors off on it and had to grind out the pieces from the end. I am going to try to drill out the remainder and save the threads as soon as I can get a right-angle drill so I can get a larger bit on it.

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The brass is too soft for extractors all it tends to to is expand the plug more making it tighter, your car has the lycoming engine? Big monster of a motor but nice looking.. why not just remove the lower rad hose will drain the water low enought to remove the head... Have fun retorquing the head down too many nuts did my Straight 8 Packard, 31 headnuts 3 times around and then redo it after its hot...pain in the b..

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Just to close this thread out... I have managed to drill out the remainder of the plug with a right angle drill without messing up the threads too much. Cleaned the threads up with a tap and now have a new hex-headed plug installed with anti-sieze.

I was unable to get it out with heat although it may be that my torch was just too weak considering the thermal mass of the block and the remaining water behind the plug. After breaking off a #4 extractor and grinding out the pieces, there was nothing to be done but drill. Even when there was nothing left but brass in the threads, those pieces still would not come out except with a tap. I suspect that the old plug was installed with type 1 or 2 sealant that had cemented it in place. There is a lesson here somewhere for those who may think that theirs is the last restoration that one of these old classics may ever need and who do a job so that it can't be undone.

Thanks for all of the advice.

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