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MG MGA - broken tap - I shoulda gone to church

Best way to get a tap out ? I've never broken one after hundreds of times, this one, a Snap-on just gave up the ghost, no big handle, 6 full threads, no hard spots GRRRRRRRRRR! It happened on the exhaust manifold studs. It could be wire EDM'ed I guess, was hoping to just do it myself. Could it be center punched out with a 2 LB sledge ? Jack
JR Jack

Get some very small drill bits in increasing sizes. Start with the smallest one and make a hole dead-center in the tap. Use this hole to guide the next bit and so on til you can dig the debris out. It will not be fast, but it will work.

Failing that, you can make a mess of it, drill a larger hole and use a larger stud. Or heli-coil it.

Or, drill it out and use a nut and bolt.

You have options.

If you have enough of the broken tap sticking out of the manifold maybe you could weld a rod to it. I've not had much success drilling out taps and similar because the steel is so hard. .........Mike
Mike Moore

You could try a tap extractor-
gary starr

You can also try this

JL Cheatham

A tap extractor may work, although I've never seen a succesful attempt with one. That being said if you were just cleaning the the threads it might not be that tight in the hole and the extractor might work.
Ocasionally using a mechanics hammer and a small punch in one of the flutes of the tap and tapping in the direction to unscrew the tap works if it is not jammed too tight in the hole.
As far as drilling you would need carbide drill bits to drill the high speed steel that taps are made of. You could end up with a mess if the drill is not centered. You would be best to EDM it out if the punch or extractors don't work.

Good Luck,
L Poupard

While it would be difficult to do with a cast iron head without causing more damage, the old way of softening a broken tap was to heat it to red heat and douse with hydrated lime. You can then drill out

Mike Ellsmore

Many thanks to all who took the time to reply with suggestions and opinions. I tried most of the mechanical hints and nothing really worked. I even tried a pair of needle nose pliers slid down along side of the tap and then a big screwdriver between the blades to twist it out. That worked a little bit until the plier blades started to sieze and bend, &$@)*^%@*. I'm giving up the trial & error and taking it to a machine shop like and have then wire EDM the bugger! Thanks again everyone...............Jack
JR Jack

OK I'll bite! What is "EDM"?

Barry Gannon

Barry - 'EDM' is electronic discharge machine. Modern day machine shops use them to cut or remove metal in a small area using intense localized heat. Normally the part to be EDM'ed is submerged in a fluid and then a + & - charge is applied. That is a basic uneducated answer as I know it. Jack
JR Jack

Thanks Jack. Now I can make out that I'm 'tech' savvy!

Barry Gannon

This thread was discussed between 18/09/2016 and 29/09/2016

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