Heat, oil and tapping will unstick most nuts and bolts in metal. Apply only enough heat to cause expansion in the entire bolt. If the area is soaked with penetrant, spray it with nonflammable brake cleaner to remove it before you apply heat. Keep a fire extinguisher nearby. Once you’ve established that it’s safe, aim the flame at the bolt head or nut, not the surrounding metal. Heat for about 15 seconds, but don’t get it cherry red. Then spray the bolt head with water to cool it quickly. Continue spraying until it no longer steams. The expansion/contraction cracks the rust, so add more rust penetrant and let it soak in. Tap the end of the bolt a half dozen times with a hammer to help loosen the threads and allow the oil to penetrate. Wait another minute or so for the oil to work, and then use your wrench.
When a bolt head has become so rounded that a wrench won’t get a bite, use a locking pliers. Get a tight grip: You may have only two or three chances before the head gets so rounded that even this won’t work. Use penetrating oil, heat and tapping if it slips after your first try.
An adjustable wrench isn't the ideal tool for loosening stuck fasteners because it can round over the head, making matters worse. But if an adjustable wrench is your only option, here's your best shot at preserving the shoulders on the nut or bolt head: Slide on the wrench all the way, so there's full contact at the back of the jaws. Then tighten the wrench thumbscrew so there's no play at all in the jaws. Always turn the wrench handle toward the lower jaw, never away from it.
Box-end wrenches work better than sockets on stuck heads because they twist in the same plane as the head, rather than being offset by an inch or more. That offset means sockets are likelier to slip off heads and round over shoulders. Fit the closed end of the wrench over the bolt head and try tugging in short pulses, instead of a full-throttle pull. That’ll help loosen rust-bonded surfaces. If that doesn’t do it, tap on the wrench with a plastic, brass or wooden mallet. It’s a good way to loosen the bones in your hand, too, so wear leather gloves and keep your fingers well away from the impact zone!
Sacrificing a Tool
It might seem sacrilegious to destroy a tool, but sometimes working in narrow or confined spaces makes it necessary. That’s where your grinder comes in. Use it to make wrenches thinner and screwdrivers skinnier and to add tapers to sockets so they fit into tight recesses. But this technique comes with a warning. Grinding a tool compromises its integrity, so take extra precautions when using it (wear goggles and gloves). When you’re done, toss the modified tool and get a new one—it’s no longer safe for use on other jobs.
Mangled Slot, Solution 2: Use a hacksaw to cut a new slot at a right angle to the old one. For big screws, put two blades in your hacksaw, right next to each other, and cut a wider slot so you can use a big screwdriver. This is also a great way to get a grip on the head of a stuck carriage bolt, which has no slot or flats.
When the slot on a fastener is too damaged to insert the tip of a screwdriver, file down the sides so you can turn it with a wrench, or cut a new slot in the head with a hacksaw.
When there’s no other solution—when heat, penetrating oil and wrenches have all failed—cut off bolt heads or nuts with a hacksaw, reciprocating saw or or, better yet, a cutoff tool. Some smaller fasteners, especially rivets and flathead bolts, may be easier to drill out than to cut.
When you’re dealing with really big stuck bolts, a pipe wrench might be your best option, especially if you don’t own a giant set of wrenches or sockets. The long handle and aggressive jaw teeth will loosen the most stubborn bolts. Just make sure you get the jaws tight against the shoulders. Pipe wrenches are also a go-to tool when bolt shoulders have been rounded over.
Be Gentle With Spark Plugs
If you snap off a spark plug or strip the threads, you’ll have a real nightmare on your hands. So if a plug shows any sign of seizing, stop and spray on rust penetrant. Let it sit for at least 30 minutes and try to loosen it just a one-eighth turn. Don’t get greedy and keep turning. Add more penetrant and turn the plug in and out slightly to work penetrant down into the threads. Saturate with penetrant and tighten/loosen only an eighth of a turn at a time. Eventually, it’ll start turning freely and you’ll be able to back it out.
A wrench on a screwdriver blade will help beat that big screw that won't budge. First select the largest screwdriver that'll fit, and tap the butt of the screwdriver handle with a hammer to loosen the thread bond. Lean your weight onto the screwdriver to keep it in the slot as you turn it with the wrench. Careful—too much torque will bend the screwdriver tip.
Be a cheater by slipping a short length of pipe—a cheater bar—over the end of your tool handle. The extra length gives you major-league leverage. Be careful, though, not to use so much force that you break the tool or break the head off the shank of the bolt.
And since we're talking about force, a word here about sockets: You'll find that six-point sockets get a better grip on hex nuts and bolts than garden variety 12-point sockets, which are designed to fit both hex and square fasteners.
The cheater bar technique can exceed the design strength of the tool, cause it to break and void the tool warranty, wear eye protection.
You may not need a nut splitter very often. But when you run into a situation where you can’t reach a bolt head to prevent it from turning, a nut splitter can sometimes save the day. Just slip the tool over the nut and center the chisel end (of the nut splitter) on a nut flat. Hand-tighten the chisel before cranking on it with a ratchet and socket. Continue turning the ratchet until you hear a loud “crack,” and the hard work is done. Of course, then you have to run to the store to buy a new nut. But least you can complete the repair without having to resort to nuclear weaponry. Buy a nut splitter at any auto parts store or at an online tool seller. (One example is the TEKTON 7580 Nut Splitter Set available through our affiliation with amazon.com.)
A screw extractor could save your day. It will grab just about any threaded fastener and remove it—even if the head has snapped off. It usually comes with a hardened drill bit to drill a hole in the center of your stubborn screw or bolt. Then you turn the extractor counterclockwise into the hole. Because of its tapered shape and left hand thread, the extractor will jam in the hole and then begin to turn out the screw. It's available at hardware stores and home centers.
An impact driver works with a bladed or Phillips head screwdriver bit, or a socket head. Striking the tool does three things at once: The blow loosens the thread bond; the downward force keeps the tool in the slot; and the head of the tool turns 20 degrees in the loosening direction. Make sure the screw slot is clean and free of debris. Find it at Sears.com and home centers.
If your car or truck wheels are fused to the rotors and won’t pull free, try this tip. Jack up the truck, loosen the lugs and prop a 2x10 against the tire. Then pound away with a sledgehammer. After a few swings, the wheel will pop right off. But if you wait until you have a flat on the side of the road, you won’t have a sledge to free up a stuck wheel. So before you head out on that road trip, maybe you should rotate those tires and make sure your wheels aren’t stuck, especially if you have an older car with some rust.
A ball mount that’s been in the receiver hitch too long can rust in place. Here’s the trick for freeing it up. Use an air chisel (about $30 at any home center or auto parts store) and a special 1-in. hammer impact chisel.
After saturating the receiver hitch with penetrant, hold the hammer alongside the receiver tube and pull the trigger. Let the air chisel chatter away at the hitch for a minute or so. Then repeat on the other side of the hitch and try sliding the shaft out. You may have to try a few times and give the hitch a few whacks with a maul, but eventually it’ll come out. Before slipping it back in, coat the shaft with water-resistant marine grease so it won’t get stuck again.