The Stovebolt Site Forums The Shop Area Engine Shop Need way to remove broken tap from crank end

That's right....I blew it. I broke off a 3/8 24 ta[ in the end of the crank. I was following advice from the board to install a bolt in the end of the crank to hold the harmonic balancer on. There were reports on the board of HBs going thru the radiators. Anyway, I installed the bolt, but now when putting the engine together after a rebuild, I thought I'd deepen and strengthen my bolt hold. I twisted it too hard and it is broken off and very stuck in there with no projecting piece to grab. Has anyone had any luck with carbide drills or tap flute extractors? Next option is to install the HB with loctite. Thanks - Scott

At the machine shop that I work in I have broken many taps. Try using a punch and just smack the tap a couple of times. A tap is brittle. Some times you can just shatter the tap. And when that does not work a carbide drill bit works but you have to be steady because the carbide will break also. Good Luck.

A couple of options come to mind Scott ;
The most efficient , cleanest , costliest , is to take it to a large machine shop and have the tap spark eroded out. You may still have to retap and fit a helicoil .
Alternatively you could try to destroy the tap by pounding it with a punch , but this is high risk , and you will end up ruining the hole and have to redrill and retap for a larger bolt , or helicoil , also pricey.
Normally the HB is a drive fit on the crank , you should only need a little 620 loctite if it slips on easy .

Dang . . . I did that once, let me tell you that is going to be a real butt-itch!

Do yourself a favor if you plan on trying to shatter it - wear gloves, wear goggles AND wear a face shield. I have a nice scar in the meat of my left thumb/palm from a tap that shattered while I was beating on it with a hardened punch.

I felt a slight twinge of pain and looked at it and it was bleeding a little. I didn't think anything of it because I didn't realize a piece of the tap was deep in my hand. A few weeks later at a regular drs appt I asked the doc to look at it and after an xray and a few seconds with a scalpel . . . it felt worse, but improved a lot over the next few days.

oh . . . and I did get the tap out - but had to use a heli-coil because the threads were so boogered up.

Dusty,Ken,JLV5337- Thanks for the "been there" tap tips. The safety tip is good also....When I was 12 I put a chip from a train ball bearing race into my eye. Biggest chip the experienced Dr. ever took out without taking out the eye too!

Anyway, I think I'll suit up and try a couple whacks. I suppose you mean a drift punch. I tried exotic drill bits that were designed for "hardened metal"...They didn't wear out, but they didn't cut either.

I think if my own devices fail, I will go the loctite route.

Thanks again for the good advice! - Scott

The one tap I have broken off I got out by applying lots of PB blaster and used a skinny set of needle nose pliers as a pin wrench between the flutes of the tap. I was able to get it out pretty easily that way. I didn't even ruin the threads.

Standard practice on the balancer bolt is to use one for a small block, you buy the bolt and washer together. And it's 7/16NF threads, so you will be able to ream and tap your hole. Be sure to use a lubricant, tap oil is the best, but 3 in 1 will work in a pinch. And now you know how hard not to turn the tap.

My buddy did this recently, we ordered a tap extractor from our local "real" parts store, was $20 but worked like a charm. It is a specially hardened needlenose type thing, turn counterclockwise & broken tap comes right out.Now we have one for next time. Brian

"64 fleetside" has got the best idea!!

Bought a full set of tap extractors from the tool guy only have broken one tap in a manifold used the tool saved twice what I paid for it.
Neat tool has fingers that go insde of the flutes