How to Remove a Broken Bolt (Snapped Off Flush or Below)

October 10, 2026

How you remove a broken bolt depends on where it snapped. If a stub sticks out, grip it with locking pliers or two nuts. If it broke off flush or below the surface, center punch it, drill a pilot hole with a left-hand bit and use an extractor, and if all of that fails, drill it out and re-tap the thread. First, work out why it broke, because that tells you how hard the rest of it will fight.

What you need

Penetrating oil, a wire brush and safety glasses
A center punch, a hammer and locking pliers
A drill with reverse and variable speed, plus left-hand drill bits (cobalt ones cut hard bolts better)
Cutting oil
An extractor: a 6-piece screw extractor set for small broken screws and bolts, or a spiral extractor sized for a larger bolt
A tap and tap wrench in the bolt's thread size, and a thread repair insert kit in case the thread is damaged
Jack stands on firm ground if you're under the car, and a cold engine if you're working on one

First, look at what's left

If the head is still there and only its recess or corners are damaged, you need the methods in how to remove a stripped screw instead. A truly broken bolt falls into one of three cases, and each has its own methods below:

A stub sticks out: the easiest case. You can grip it without drilling.
Broken off flush: nothing to grip, so you punch, drill or extract.
Broken below the surface: the same tools, but drilling straight gets harder.

Then think about how it broke:

Snapped while tightening. Once the head is gone, the rest of the bolt is no longer stretched. If the thread wasn't rusty, the piece left in the hole is often loose and turns out easily.
Snapped while loosening. The thread is still seized by rust or threadlocker, and it will resist every method below. Free it first with oil, time and careful heat, as described in how to loosen a rusted or seized bolt.

One more check: if the head snapped off a bolt that holds a part on, remove that part's other fasteners and lift it off. With the part gone, there's usually a stub of bolt standing proud of the hole.

If a stub sticks out

Wire brush the stub, soak it with penetrating oil and give it at least 15 minutes.
Clamp locking pliers on it as tight as they'll go, as low as you can, and turn counterclockwise. Re-clamp if they slip.
If the stub still has good thread on it, such as a broken stud, thread on two nuts and tighten them hard against each other. Then turn the lower nut counterclockwise: the locked pair turns the stud.
File two flats on the stub so a wrench can grip it, or cut a slot across it with a rotary tool or hacksaw for a large flat screwdriver.
If enough stands proud, try a bolt extractor socket. Pick the size that needs a light tap to go on, and its reverse spiral bites into the round stub much as it would into a rounded head.
If you can weld, or know a shop that can, weld a nut onto the stub and turn it with a wrench. The welding heat helps break the rust too.

If it broke off flush

Try a punch first

If the bolt snapped while being tightened, try this before you drill. Angle a sharp center punch into the broken face near its edge and tap it with a hammer so it pushes counterclockwise. Move around the edge and repeat. A loose stub will start to turn and can be walked out. If it doesn't move at all, it's seized: go straight to drilling.

Drill with a left-hand bit

A left-hand bit cuts when the drill runs in reverse, so every turn pushes the bolt in the loosening direction. Often it grabs and spins the bolt out before you need an extractor.

File or grind the broken face flat if it's jagged, so the punch and drill don't skid.
Center punch the exact middle. Check it from two angles. An off-center hole drifts into the thread of the hole.
Set the drill to reverse and a low speed. Start with a small bit, add a drop of cutting oil and press firmly and steadily.
Keep the drill square to the bolt. Ask someone to watch from the side if you can.
If the bolt starts to turn, stop pushing and let the bit walk it out.
If it doesn't, step up one bit size at a time. Keep the hole well inside the bolt so you never reach the thread.

Use an extractor

For small screws and small bolts, the JUSMIR double-ended extractor set skips the separate pilot hole. Its six bits, sizes #0 to #4, each have a cutting end and an extracting end, and they work with an ordinary drill:

Choose a bit whose cutting end fits inside the broken face without reaching the thread.
Drill in reverse at low speed to cut a shallow seat in the face.
Flip the bit, keep the drill in reverse, press firmly and run it slowly. The extracting end bites into the seat and backs the fastener out.

The set is made for damaged screws, so it suits smaller fasteners best. For a larger snapped bolt, drill a pilot hole sized for a spiral extractor and turn the extractor by hand with a tap wrench. Our guide on how to use a screw extractor without breaking it covers sizing, speed and what to do if one snaps. The short version: no impact drivers, no side load, and stop when firm pressure isn't working.

If it broke below the surface

Use the same punch, left-hand bit and extractor methods, but take more care with alignment, because the hole's edge hides the bolt's true center. Shine a flashlight down the hole, use a smaller punch, and blow or vacuum chips out often so you can see. If the part can come off the car, a drill press keeps the hole straight. A drill guide (a hardened sleeve that holds the bit centered) does the same job on the car.

Last resort: drill it out and re-tap

Drill down the center of the bolt, stepping up through bit sizes.
Stop just under the tap drill size for that thread. For standard metric threads, that's the bolt diameter minus the thread pitch: 5.0 mm for M6 x 1.0, 6.8 mm for M8 x 1.25, 8.5 mm for M10 x 1.5 and 10.2 mm for M12 x 1.75.
The thin shell of bolt left in the thread often collapses. Pick the pieces out with a pick.
Run a tap of the original size through by hand with cutting oil, backing it off every half turn to break the chips.
If the thread is damaged, a thread repair insert kit lets you drill and tap oversize, then fit an insert that restores the original size.

Broken bolt in an engine block or aluminum part

Work on a cold engine, and plug or tape over nearby openings so chips can't fall inside.
Many engine parts are aluminum. When you drill a steel bolt in aluminum, the bit tends to wander toward the softer metal, so punch and drill with extra care.
Exhaust manifold studs and thermostat housing bolts are common victims. Both are usually seized, so oil and heat matter more than force.
Machine shops can remove broken bolts and extractors with spark erosion (EDM) without touching the thread. For a cylinder head, that's often the cheapest route overall.

Mistakes to avoid

Drilling forward with a normal bit before trying a left-hand one. Forward drilling pushes the bolt in the tightening direction.
Drilling off center, or too big, and cutting into the thread.
Forcing a small extractor into a seized bolt. Hardened extractors snap, and a broken extractor is much harder to drill than the bolt.
Skipping the soak on a bolt that snapped while loosening.
Guessing the replacement. Fit a new bolt of the same size, length and strength grade, and torque it to your vehicle's spec.

When to call a pro

If the bolt is in a cylinder head, engine block, exhaust manifold, brake or suspension part and your first careful attempt fails, stop. A shop can weld a nut onto a stub in minutes, drill accurately with proper guides or send it for spark erosion, and that costs far less than a ruined thread in an expensive part.

FAQ

How do you remove a broken bolt without an extractor?

Grip a stub with locking pliers or two locked nuts, walk a loose flush bolt out with a punch, or drill with a left-hand bit, which often spins the bolt out. Welding a nut on, or drilling out and re-tapping, are the remaining options.

How do you remove a broken bolt that is flush?

Try a punch angled counterclockwise first. If it won't move, center punch, drill in reverse with a left-hand bit and use an extractor if the bit doesn't spin it out.

How do you get a broken bolt out of an engine block?

Cold engine, openings covered, a long soak with penetrating oil, then a punch, left-hand bit or extractor, drilled dead center. If that fails, a shop can weld a nut on or use spark erosion.

Can you remove a broken bolt without drilling?

Often, yes: if a stub sticks out, or if the bolt snapped while being tightened and the piece left is loose enough to turn with a punch.

How do you remove a broken bolt from aluminum?

Soak it, then use gentle heat on the aluminum around it, which expands more than the steel bolt. Drill with extra care, because the bit wanders toward the softer aluminum. If the thread is damaged, a thread repair insert restores it.

Browse all tools for stuck bolts and screws.

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