Use an Impact Driver When You Can
An impact driver and a set of high-end hex-shaft nut drivers are all you need to loosen small nuts and bolts. For larger nuts and bolts, you'll need an impact gun and a set of six-point, impact-rated (black finish) sockets. Ordinary chrome sockets can't handle impact work and may crack or shatter under the stress. And because impact-rated sockets have six points instead of 12, they're less likely to round over bolt and nut heads.
Stuck Fasteners Can Bite You
When it comes to causing pain, stuck fasteners can get the job done. Right when you're giving a stuck bolt all your muscle, wrenches will slip, bolt heads will snap off and your hands will get smashed against something sharp. So always wear gloves and try to orient tool handles so your hands will be clear if a tool slips.
Needless to say, pounding on stubborn fasteners with hammers, mallets and sledgehammers poses similar dangers. Never use a regular hammer for metal-on-metal impact. Bits of the hardened metal can break off and become embedded in your flesh. Safety glasses are a must, as well as hearing protection when you're running some of these very power noisy tools.
Lock on to Wrecked Heads
These pliers are best known by the brand name Vise-Grip. Whatever brand you have, they'll get you out of a jam when bolt and nut shoulders are rounded, or when screw slots or Phillips crosses are stripped out. Rounded jaws work best. Make sure the jaws are seated on the flats of the nut/bolt or around the screw head, and tighten the handle as much as you possibly can before turning the fastener.
Pound a Combo Wrench
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!
Pipe Wrenches Aren't Just For Pipes
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.
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.
Heat is the Last Resort
Applying heat with a propane torch can expand a nut (or threaded opening) and loosen it. If you've tried everything and still can't free a bolt or nut, try heat. But first make sure the fastener is a good distance away from hoses, belts, gas tanks or anything else that might burn up your car or kill you in an explosion.
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, let it soak and then add vibration by tapping it with a hammer or other tool. Then try to loosen it.
Whack Stuck Wheels
Sometimes rust will fuse wheels to the rotor, making it almost impossible to pull them off. If it happens to you when you're changing a tire or working on the brakes, loosen the lugs and prop a 2x10 against the tire, then pound away with the biggest sledgehammer you have. 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.
Don't Mess Around?Cut It Off!
If you have a stuck nut/bolt that can be replaced, don't beat yourself up trying to unscrew the rusty one. Just cut off the stuck fasteners (or the parts around it if they're getting replaced) and buy new ones. Use a reciprocating saw with a hacksaw blade or, better yet, a cutoff tool. (You can get a cutoff tool for as little as $30 at any home center or hardware store.) Then take the leftovers to the store to match them up with new ones.
Try an Impact Driver
When you need to tackle stuck slotted or Phillips screws, buy a $15 hammer-style impact driver. Apply rust penetrant and allow it to soak in. Then fit the right driver bit in the end, and pound on the end with a ball-peen hammer. This shocks the fastener, cracks the rust and twists the bit, all at the same time. The hammer blow keeps the bit in the screw head, preventing further damage to the slots.
Drill Out Rivets
Removing rivets is easier than you think. Just pick a drill bit that's a tad larger than the hole in the top of the rivet. Run the drill until the washer head is loose. Then poke the rest of the rivet out of the hole.
Stuck Receiver Hitches
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. (We used the Grey Pneumatic 1' Diameter Hammer, which is available at amazon.com.)
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.
Tool purists (and tool manufacturers) hate this tip because they think it's both dangerous and an abuse of tools. It is. But sometimes it's the only way to get the job done, especially if you're removing large nuts and bolts. Slide a metal pipe over the handle of a pipe wrench, a combination wrench or a socket wrench. The pipe will add tremendous leverage. It may be hard on tools and might even break them, but on the bright side, you'll most likely break the fastener loose and have fewer strained muscles and/or bruised knuckles.
Start With a Rust Penetrant
Rust penetrants contain a solvent to dissolve rust, a lubricant to reduce friction and a surface tension reducer to get deep penetration. “Home brews” like Coca-Cola, kerosene and mineral spirits don't have all those ingredients. Neither does WD-40 (it's a great lubricant, but it's not formulated as a rust penetrant). Those products simply don't work as well or as fast as actual rust penetrants (find penetrants like Liquid Wrench Penetrating Oil, Royal Purple Maxfilm and PB Blaster at home centers and auto parts stores). Soak all the bolts for at least 15 minutes before you attempt removal.
Then Hit It With a Hammer
If rust penetrant alone doesn't work, create micro cracks in the rust with blows from a hammer, or even better, an air chisel and hammer bit. Then apply more rust penetrant and ”reshock“ the bolt head. Repeat until you can turn the bolt.
Try a Socket on Your Air Chisel
Apply even more force to a rusted bolt with an air chisel socket adapter (No. PH1050 from snapon.com). Slip a wrench onto the adapter flats and crank away while you apply air hammer blows. The dual forces break the bolt loose.
Mangled Slot, Solution 1
If the slot of a roundhead screw or bolt is chewed up beyond hope of gripping it with a screwdriver, file two flat edges on it. Then turn the head with an adjustable wrench.
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.
Split a Nut
A nut splitter will crack any no-go nut without damaging the threads of the bolt or stem that it's screwed onto. Just slip the ring over the nut and turn the tooth into the nut until it breaks. Find it at auto parts stores or online.
A Screw Extractor
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. You can find extractors at hardware stores.