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Know-How Notes: Removing Rounded-Off Bolts

Know-How Notes: Removing Rounded-Off Bolts

Know-How Notes: Removing Rounded-Off Bolts

Know-How Notes: Removing Rounded-Off Bolts

We have all had it happen. You are turning a wrench and then BAM, the head of the bolt rounds off, the wrench slips, and you bust your knuckles on the edge of something sharp. It never fails; there is always a sharp edge next to a rounded bolt waiting for your tender knuckles. Not only are you cringing in pain, but now you have a problem: that was the last bolt holding whatever part you have to remove to the car. It has to be removed, but some methods are better than others to get the job done. Here are some tips and tricks to removing rounded-off bolts.

Rounded-Off Bolt Removal Techniques

Lube it! – First things first, you should always lube up your nuts and bolts before trying to remove them, especially if they are rusty or have been in place for many years. At the first hint of a problem, stop, grab some penetrating fluid and soak it. Let it sit for 5-10 minutes and come back to it. The times you spend waiting will save you in the long run. Another lubrication trick is to heat the bolt up and then melt wax onto it. The heat wicks the wax into the threads and many times, the bolts will come right out. 

To wax a bolt, apply heat directly to the bolt. This particular bolt is a broken exhaust bolt.


Then apply some wax. This is beeswax, but you can use most any wax.


Anti-cam out fluid – If you are working with a screw, particularly a Phillips-type, apply a drop of anti-cam out fluid to the head. This will help hold the bit in place while you apply pressure. Stripping a screw head stinks.

Screwdriver – Let’s say that the bolt or screw is spinning, but not coming out because the threads are damaged. A quick way to get the bolt back to the good part of the threads is to wedge a small screwdriver or flat blade between the part and the bolt, nut, or screw head. Apply pressure to push the bolt out and unthread it. This works miracles.

Sometimes the hole itself is stripped. This trick works on screws and bolts. Slide a small blade, screwdriver or pick under the head while turning the fastener. The added pressure usually get the fastener into good threads to remove it.


Specialty socket/wrenches – If the head of the bolt or nut is chewed up and rounded, there are several specialty sockets & wrenches available to help. NAPA has several unique designs that can get you out a jamb.

Specialty wrenches like this one from Gearwrench are designed to catch on rounded corners.


Smaller wrench/socket – If you don’t have a specialty tool or are on the side of the road, try a slightly smaller socket or wrench. It is a good idea to keep both metric and SAE sockets in your car regardless of what type of bolts are used. A 12mm socket is just slightly smaller than a 1/2”, so you can tap it on with a hammer, add some lube and you might be home free.

Locking pliers – If the bolt is just completely wasted, you need some VISE-GRIP locking pliers. Locking pliers come in many sizes, so you should be able to grab a pair that will match up. Stay away from needle-nose and flat-jaw locking pliers though, as these won’t be able to get the grip you need. Instead, use the round section of the jaws.

Often a cause of rounded bolts, locking pliers are the go-to tool to remove them as well. Make sure you crank it down tight.


Heat shock – If you still can’t get it loose, grab a propane torch and put some heat on the part. You can try heating up the surrounding threads or concentrate on the bolt. Once it is good and hot, hit it with some penetrating oil. This will shock the hot metal, breaking the thread’s grip, allowing you to free the bolt.

Shocking the fastener often breaks the bond. Start by heating the area around the fastener.


Then use CRC Freeze-Off to shock cool the bolt. Only spray the bolt, leaving the surrounding threads hot. Freeze-Off has a special propellant that freezes when it is sprayed. You can try ice also.


Cut a slot – Still can’t get it? Grab the die grinder or angle grinder and cut a slot in the center of the head. This lets you use a flat blade screwdriver. If the bolt is stuck, a simple impact screwdriver will work great to give the shock the bolt needs to break free.

Weld a nut – If you can, weld a new nut to the head of the old one. This the last resort for blind fasteners (where is the not a nut on the other side) before you have to drill it out. The heat from the weld may help break the seized threads too.

If you have a broken stud or stripped nut and need a lot of torque, welding a nut on the end can get the job done.

Cut it off – Sometimes, you just have to cut it off. An angle grinder with a cut-off wheel works best, but a sawzall works great too. This is used when there is a nut and a bolt.

Drill baby, drill! – If you can’t cut it, you have to drill it out. Use a center punch to get as close to the centerline of the bolt. Use the smallest bit you can to start the hole, and then slowly work your way up. Eventually, you will get to the edge of the threads and the bolt will come out. Bolt extractors have a bad habit of breaking in the bolt, so be careful if you decide to use one. Don’t cheap out; you want good extractors, not cheapies that break.

Drilling is the last resort, and it takes patience and time. Start small and work you way up until it comes out.


After drilling, you will have to re-tap the hole. Make sure you use lube for the tap.


Using these tips, you should be able to get the job done. If you need some advice about removing rounded-off bolts, stop by your local NAPA Auto Parts Store.

To learn more about NAPA AutoCare, visit www.NAPAAutoCare.com.

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Source: NAPA Know How

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