How to remove a Rusted Bolt
It doesn’t matter where you live in the United States, there’s enough precipitation to slowly turn the nuts, bolts, and other fasteners under your car, truck, or SUV into ferrous oxide (street name: rust). And while ferrous oxide gives us the glorious reds and oranges of the Grand Canyon, it does nothing but create misery for the DIYer who likes to work on their own vehicles.
We’ve collected some of the best advice from a number of technicians around the country to assist you in your rust-busting project. Some of these you may know or may even seem obvious, while others might introduce some new techniques you haven't tried.
Removing a Rusted Bolt
1. Time is on Your Side
Unlike a professional mechanic who has to deal with a rusted fastener as soon as he raises the vehicle on the lift, as a DIYer, time is on your side. Don’t wait until the day that you’re planning to swap out pads and rotors to check and see if nuts and bolts are rusted in place. Instead, do a pre-inspection a few days before you’re planning the work. If you spot fasteners that look like they’ll be trouble, give them a treatment of quality penetrating oil so that the oil has time to work to dissolve the rust, and, well, make the job a great deal easier.
2. Remove as much Rust as Possible
If you’re able to reach the area, you should actually make this your first step. But since getting a vehicle into the garage, jacking it up, and removing the wheels to inspect the brake calipers isn’t your idea of a fun evening, you will most likely take this step when you’re ready to start work. Getting all the rust off the fasteners has two purposes: one is that it gives you a flatter, more accurate surface to match up to your tools, and second it starts to break the hold the rust has on the fasteners – less rust means less force required to free the nut or bolt.
3. Always Use the Right Tools
There’s no operation on your vehicle that’s more critical for you to have the correct tools at the ready than when freeing frozen or rusted bolts. Believe it or not, one technician told us he sees way more DIYers bring their vehicles into their shops with rusted bolts where they’ve rounded off the head because they were using the wrong tool. First, all types of pliers are out as are adjustable wrenches. The same goes for open wrenches. Don’t even try. The best way to grab the nut or bolt securely is with a socket. A 6 point is good but a 12 point is better as there’s more surface contact area, and less likelihood of slipping. Don’t use a ratchet unless you like to return tools. They’re not designed for high levels of torque. Instead, invest in a breaker bar, if you don’t already have one. The length of the lever is two to three times longer than a ratchet, delivering a much higher level of torque to the fastener.
4. Is It Thread Locker Holding You Back?
Look carefully at the bolt and see if you can spot a tiny bit of thread locking compound that may have leaked past the nut. To keep squeaks and rattles to a minimum, many carmakers are using threadlocking compound on fasteners used throughout the body and chassis. If the thread locker used is the permanent type, it’s one thing, but when the fasteners are also rusted that’s double trouble. First, follow the steps above, then add some heat from a torch to liquefy the threadlocker and soften the rust. Use caution with heat around electrical components and flammable liquids.
5. Backwards and Forwards
Like most DIY’ers you probably don’t have a lift in your garage, so you can work under your vehicle standing up. Like most of us, you’re rolling around on a creeper under a vehicle well-supported by jack stands of a sufficient rating. In this environment, it’s easy to get a little confused, especially if you’re working on the backside of a fastener. Before you start turning a wrench in that situation, make sure you’re going to be spinning it in the correct direction to loosen it.
The next issue is that once you get the bolt or nut to turn, don’t immediately assume you’re out of the woods. Often times, especially on nuts, rusty corrosion will jam into the nut or bolt while you are loosening, making it difficult to turn even once it’s been broken loose, and gets worse the more you turn the bolt. Often times, this leads to a busted bolt, or stud, and a very frustrating time. The remedy to this is to work the bolt/nut just like you would a tap – backwards and forwards. Once you get it broke loose, spray a little penetrating oil on it and go 1/4 turn forward, and 1/8 back. 1/4 forward again, and 1/8 back. Repeat over and over again, until the bolt/nut can easily be loosened without resistance the rest of the way. This is especially important on exhaust nuts and bolts. The moment you feel resistance – stop! Tighten up slightly, and then go back to reversing again. Be patient. You will save a lifetime worth of bolt-breakage frustration using this method.
6. Heat is Your Friend
Just like science tells us, heat causes things to expand. Applying a heat source, usually in the form of a torch – propane, MAP gas, or Acetylene, will expand the nut and make breaking it loose easier. Sometimes, a bolt/nut cannot budge unless heat is applied to it. While Propane torches will heat, they will not get the nut/bolt red hot like MAP gas or Acetylene will, and sometimes, you need that much. Take extra care to always make sure with any heat or flame source that there is no rubber, wiring, grease, or fuel lines around where you were working. Always size up the situation around where you are working for any hazards, and always have a fire extinguisher handy and at your side whenever working with any flame.
7. Bring in the Big Guns
A pneumatic or electric impact gun can be used, but many times it’s not practical in the area you’re working. As you’re aware, these aren’t subtle tools that can transmit information back to the DIYer about whether the bolt may fail, whereas the “backwards and forwards” method listed above, you always can feel for that resistance if something is jamming the bolt/nut up from coming off. The chances are good that something is going to break when you apply enough brute force to a rusted fastener, so try to limit using an impact on anything smaller than 5/8 socket size, as often times an impact will simply shear this bolt off. Last thing you want to do is have to drill and tap, or use a bolt extractor to remove a busted fastener.