Broken Bolt

How to remove a broken bolt, 1.75" back in a deep well of a engine casing? Specifically, not a car question, but a motorcycle question, that many a car mechanic must face, I am sure.

While reinstalling the cover to the water pump on my 2002 Suzuki DL 1000/V-strom, I was using a torque wrench to tighten down the cover. All was going well, wrench set to 18 NM, 4 of five bolts set. Last bolt, kept turning without wrench releasing, about 3 turns more than other bolts when the bolt sheard off, nearly straight across. The bolt was a deep bolt with the last 0.5 inch threaded, and it sheard about in the middle of the threaded section. The remainder of the bolt is back inside of the of the water pump case, recessed about 1.75 inches. How to best get the bolt out of this hole and me out of this mess?

One way mechanics remove broken off fasteners is to weld a washer and nut thru the center to the broken fastener. But if this broken fastener is recessed it would be impossible to get a MIG gun close enough to weld, let alone hold the washer/nut centered over the broken fastener at the same time.

If I ran into this, I would drill out the broken fastener and install a Heli-Coil thread repair kit.


There are various kinds of bolt extractors that may do the trick for you. The ones I have on mind are the spiral screw-type extractors that look like this:

You drill a hole out in the center of the stud and the idea is that they are reverse direction from the threads, so as you try to back out the bolt, the extractor screws in to take an increasingly better bite. Check the local hardware store - most carry things like this.

These are called EZ-outs. And can work fine. The problem is as you turn an EZ-out, it causes the broken fastener to expand where the hole was drilled for the EZ-out to be inserted. This causes the threads of the broken fastener to expand and grip the threaded hole you’re trying extract the fastener out of. And if the EZ-out bit breaks off when attempting this, good luck trying to drill thru an EZ-out.


I can’t think of a tool with a more missleading name.

Your problem is presumably that you tried to install a long bolt into a short hole. That’s why the bolt broke the way it did. Because it’s broken like that it probably is jammed in the threaded hole. This will make it difficult to break free, but once you do that it should thread out very easily.

If this were my project I’d certainly try using an E-Z out, I’ve used them with success many times. When the bolt is really badly stuck they’re no help at all, and they’ll expand the broken stud as Tester says. To help offset this I’d make it a point to use a left handed drill bit to drill the hole for the E-Z out, and make sure you get that hole centered perfectly. Use the largest bit you can without damaging the threads.

This can be done without further damage, but it will require patience and moving slowly, and being sure of what you’re doing. Now is no time for more mistakes. Go slow and carefully and you can get this bolt out.