How to Loosen Stuck Bolts

Loosen the most stubborn fasteners without breaking a sweat

Frozen, rusted bolts are a given in almost every auto or truck repair job. Instead of using anger and brute force, try one of these four proven techniques to work them loose.

By the DIY experts of The Family Handyman Magazine

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).

Start by soaking all the bolts for at least 15 minutes before you attempt removal (Photo 1). If they still won't budge, move on to the “shocking” phase (Photo 2). You can smack the bolt heads with a hammer. But I get the best results with an air chisel and hammer bit (GRY No. CH117 hammer bit; from www.tooldiscounter.com).

I've also had good luck with an air chisel socket adapter (No. PH1050; from www.snapon.com). Slip an impact socket onto the adapter and pull the trigger (Photo 3).

If neither of those tricks works, heat and cool the bolt. The expansion and contraction will open cracks in the rust and allow the penetrant to work its magic. But before you apply heat, wash off all the rust penetrant (most penetrants are flammable). Next, remove any rubber or plastic parts that may be damaged by heat. Then heat the bolt head with a propane torch (Photo 4). Immediately shock the bolt with water spray (Photo 5). Once the bolt cools, reapply rust penetrant and try removing it.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Air compressor
  • Air hose
  • Impact Wench
  • Hammer
  • Safety glasses
  • Soldering torch
  • Socket/ratchet set
  • Wrench set

You'll also need an air chisel, an air chisel hammer bit and an air chisel adapter.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Rust penetrant