0) IS IT SUPPOSED TO COME UNDONE? Might seem an obvious question but sometimes fasteners are 'captive' and aren't supposed to turn. Or, it might be a left hand thread. Some crank bolts are, so they don't undo during rotation of the engine. Chryslers "Mopars" in the US up until 1970 had the wheel 'Lug' nuts do up the other way on each side of the car so that they didn't work loose from wheel rotation.
1) USE THE RIGHT SOCKET. Seems obvious doesn’t it, but that doesn’t mean just the right size. Use a 6 point socket not a 12 (or more) as they can round off the corners of the fastener if its stuck. 6 point sockets grab more surface area, away from the corners. They’re cheap too, we carry a good range in stock and you can buy them singly for that stuck little rascal…
2) APPLY MORE FORCE. Obvious but make sure you’ve got purchase on the whole nut or bolt first (see 1). Use a longer wrench and therefore use leverage to apply more pressure. That doesn’t mean going straight for the breaker bar, but that’s an option. Sometimes just switching from a 1/4” drive ratchet to a 1/2” means you can apply more force as the head is stronger and the wrench arm longer. Alternatively, find a length of tube to slide over the wrench to extend the handle.
3) PENETRATING OIL. Some might start with this but you might want to go straight to 5 and you don’t want inflammable fluid hanging around then. Penetrating oil comes in lots of variants and trust me, they vary. Many will reach for their universal lubricant, but dedicated release agents work better. If possible, leave the fastener to soak overnight.
4) IMPACT WRENCH. Utterly over used at tyre shops and utterly brilliant on everything else. Only the cost prohibits one from being in every home mechanics toolkit (we’re working on that). Hammering on the fastener whilst it twists, an impact wrench is the effortless solution. Make sure you only use the sockets that are designed for use with an impact wrench though. Steel fragments in the eyes is so inconvenient.
5) HEAT. Nothing like applying some heat to the nut. Get it nice and hot (preferably orange) with a blowlamp or Oxy/Acetylene. It goes without saying, don’t use this method near rubber seals, cables, upholstery or fuel lines!! The nut expands and the ‘bond’ is broken. The clean, safe, modern way is to use a dedicated Induction heater. These have a coil that slips over the fastener. When electricity is passed through the coil in creates a magnetic field which vibrates the metal atoms and causes heating. Clean and safe. Sadly these aren’t at a price the average mechanic can justify at present.
6) IReOx RUST REMOVER. If you can place the fastener in an bath of diluted IReOx, within a day or two the IReOx will have eaten the rust, all the way into the threads. Then you can just undo the fastener normally. Its a ‘soak and forget’ solution as you can’t leave the item in the IReOx too long, it doesn’t harm the metal. Its also friendly to rubber seals and most paints. Its disadvantage is the time it takes and the need to immerse the item.
7) ROUNDED OFF FASTENERS. If your nuts corners are rounded off, or they are so corroded they look like they will on first attempt, there are various options of specialised sockets that grip the steel in different ways. We think we’ve tried them all and the ones we stock were by far the best in our trials. They grip the flats of the fastener and the more torque you apply, the more they grip. Worth the investment if you undo a lot of rusty bolts or live near a convent and want to keep the bad language down.
8) STUCK SCREWS. The annoying thing about stuck set screws is that its easy to damage the head by applying too much force as they can’t take anywhere near the torque of a bolt. Make sure you have exactly the right bit to fit snugly and if the screw is painted over, chip that off first. The door hinge bolts on Suzuki SJ’s and MGB’s spring to mind as being the worse little rascals. We were chuffed to discover the ‘Shake’n’break’ made by a little company in the USA. It goes in your air chisel and literally shakes the set screw loose. Hasn’t failed us yet. See the link below.
9) GRIND IT. Is a 50p bolt worth an hours frustration? For some applications it can be simpler to put a cutting disk in the grinder and slice the dam thing off. When you get about halfway through and the bolt is glowing orange you’ll see it come free. Grrrrr! Check the bolt head for markings so you can replace with the same grade.
10) DRILL IT. Sometimes there is no alternative but to drill a bolt out. This must be one of the most frustrating and nerve wracking fixes restorers have to do, depending on the value/replaceability of the item the bolt is screwed into! Mark very carefully the centre of the bolt, not easy if its already distorted, dot punch it, then drill. You need a drill bit that is harder than the bolt, such as cobalt. If you are drilling into a threaded component and the drill wanders and damages the thread you can consider a remedy such as Helicoiling. Our thoughts are with you on this one.
11) WELD IT. If the head has rounded off, find a nut the right size and weld it to the old head. The heat will help it loosen and you'll have a nice new hex to apply pressure to.
12) FOUR CANDLES. For this trick you don''t want a tallow candle, or a Beeswax or a Soy, you want a good old Paraffin wax candle. Heat the fastener, then light the candle. Drip the molten wax onto the nut/bolt joint. The Paraffin pentrates the joint, freeing it and once hardened it lubricates the thread for undoing. Works nicely on small fasteners but a bit of a phaff under a car.
FORGET: In our experience there are two tools that are just a waste of time but I’m sure they worked for someone, somewhere at sometime and they’ll correct me:
Screw extractors: Quality ones that grip the steel and don’t snap probably exist…somewhere.
Nut splitters: You have to heat the nut to soften it first, in which case it usually comes undone anyway. Also invariably damages the bolt thread.