Broken tap

You know that saying that a two hour job is a broken bolt away from a three day ordeal. Well we have a broken bolt in the block of my son’s Nissan Spec-V, 2,5L engine. It is a 10.9 grade bolt, 10mm. Drilled it out with a 3/16" drill all they way to the end.

Went hard as we dared with the easi-out, would not budge. So I got the idea to tap 8 x 1 threads down the-middle of the bolt and it went well, until the last possible 1/4 turn. Had I stopped, it would have been OK. But NOOO. Just a little more and the tap snapped somewhere inside the bolt, apparently at an angle because it will not back out. Tried a little harder and it broke again at the bolt.

I tried drilling with a cobalt drill bit, no luck. I tried some diamond coated dremmel bits and they would cut into the tap but not very far as the diamond grit is mostly on the sides of the but for grinding and not on the tip for drilling. Tried some conical stone dremmel bits and they would cut into the tap but did not last very long. It would probably take a 100 bits to get the tap out and even the cheap stone ones are not that cheap.

Any ideas? Suggestions?

Broken tap removal tool.



I was going to say get the wire welder out and fill the hole and weld a nut on top. There are a couple old guys on YouTube showing various methods that I’d look at first.

If the tap breaks horizontally, that is the best case scenario. Sometimes, they break longitudinally along the length of the tap and then they can get super jammed in the hole and be very difficult to remove. One of the better extractor tools out there are these guys-

The have very positive flute engagement along the length of the tap and are hardened. You can find these at many tool stores or even online at places like Amazon.

Whatever tool you choose, be careful to match the number of flutes in your broken tap to the tool.

These work under most scenarios but I have seen some cases where only an EDM could get the tap out. Hopefully yours broke horizontally and you can get them out fairly easily. Good luck!

Wow, I never knew about such a thing… Thank you all for the replies and a lesson learned!

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Your local machine shop probably has a special purpose tool for that exact problem. Suggest to give them a call and ask for the options.

What part of engine is bolt for? I broke a bolt on my aluminum timing cover. I think the cover was removable with great effort.

Left handed drill bits are good when drilling out broken bolts and stuff…

I was wondering where the heck one would go to get a set of those if you were not in a large city, sitting with a broken tap in an engine you couldn’t remove to take it to the machine shop. Then I see they listed fastenal.

They make drill bits specifically for drilling out taps but they need to be run in a mill. That’s more suited to production fabrication of parts where it can be fixtured for repair. If you put one of those in a hand drill, you’d need an egg shaped tap and bolt to match the hole afterward… :grinning:

Several years ago, a Friend was removing the front, upper engine mount on his motorcycle and one of the two bolts broke off flush with the treaded frame mount. He borrowed my Craftsman’s Screw Extractors and followed the instructions carefully, but something went wrong and the extractor broke off just below the broken bolt.

Ultimately, he just put it back together with just the one bolt…

Since I have just learned about the tap extractor in this posting, what would have been the advice for him?

Yeah, I wouldn’t try to drill out a tap, I can normally get the broken bolt out by drilling it or welding a nut to it, a broken tap just ruins your day… I have slowly broken a tap out before, slowly piece by piece, just picking away at it… sux…
My 1/2 pneumatic, high torque, 500 RPM max, drill will turn very very slowly when needed, and when it catches, just hope you are holding on with 2 hands or it is going to hurt… I’m sure it has friends on here also…

I’ve learned to respect 1/2 “ powerhouses. I was drilling a five inch vent hole in siding when the thing kicked back. Learned to hang on and take it easy after that. No broken bones though.

Sounds precarious.
So it’s a threaded boss in a tubular frame?

They do make carbide bits that could drill into the extractor. The key would be to start small but the hazard there is the smaller the bit, the more likely to break it- they are very hard as well and don’t take off axis pressure very well :grinning:

If it was mine to deal with, I would at least try drilling the extractor first. It’s left hand so the drilling will be working to reverse it out of the hole.

Any steps I take would be progressively more impactful and trying not to damage the paint would be first consideration.

Next attempt for me would be to wire weld a nut onto the bolt extractor combo. Forming a head on the extractor first, then welding the center of the nut into that “bead”.

Assuming that didn’t work, I would be asking around if anyone has access to an EDM machine. I have had decent luck finding people willing to help on stuff like this, often for free. However, a suitcase of beer seems to work as payment :wink:

The nuclear option is to bash up the extractor with a hardened punch and pick out the bits. This will require a lot of patience and control to avoid bending the tubing.

I wouldn’t leave only the one mounting bolt without finding some sort of solution to support the motor entirely…

The bolt in question holds the bottom of the header to the block. When the car was new, he replaced the OEM header to a NISMO street header to eliminate the warm up cat, aka pre-cat.

In the 2002 and 2003 Spec-V and Altima’s with manual transmissions, during deceleration when the driver downshifts, it would suck fragments of the pre-cat back into the engine. Hard charging driving would cause exhaust pulses that would break up the ceramics in the pre-cat.

This was mostly with manual transmissions as most drivers with automatics do not downshift manually. This especially affected the Spec-V as the type of driver that was attracted to this type of car were generally hard chargers.

Anyway Nissan redesigned the pre-cat but didn’t really tell anyone so even in 2006, a lot of Spec-V buyers still thought that this issue still existed.

In replacing the header, my son used all the original bolts in their original locations. The header is held to the head with studs, but to relieve any stress on the header gasket, the bottom of the header had a single bolt to hold it from moving. The original bolt, like all the other bolts was plated, but in removing and then reinstalling this bolt, apparently the coating got worn off, so over the next 18 years, dissimilar metal corrosion welded the bolt in place.

You can bet when this thing goes back together, all the bolts are going to get a coating of anti-seize.

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My diff was noisy and I found out spider retaining bolt was sheared off. I got it out. Then I ended up replacing entire rear end.