If you have a stuck bolt, rounded bolt or stuck nut – any type of fastener you can’t free – then your productivity on a job can quickly hit zero. I’ve encountered this situation most often during automotive work. The heat, oxidation and tight work spaces make stuck bolts and rusted nuts a common occurrence when you’re under the car. However, these tips would apply anywhere. So, after removing an entire engine, I had plenty of practice – and here are my tips – and the order you should use them in to remove stuck bolts.
Seized Nuts and Bolts:
- PB Blaster and a wire brush: As soon as you see rust, reach for these two items. Getting old rust off of the thread will help the nut turn. I used to think the difference in PB Blaster and WD-40 was just marketing, but PB is absolutely better at freeing rusted bolts. PB is a penetrating oil and WD-40, despite the uses listed on the can, is a water displacer and not as good at freeing stuck bolts.
- Step 1.5. Use the right sized socket! If it’s metric, go metric. Some SAE and metric may seem close, but the right socket won’t move at all on the bolt or nut. Close only counts in horseshoes and hand grenades. You should also use six-point sockets instead of 12 for cracking bolts. Twelve-point may give you play with the breaker bar location, but they can strip a fastener in no time if they slip.
- Breaker bar: Freeing seized bolts is mostly about torque and the longer the handle and the higher the load tolerance of the tool, the better chance you have. I have a 30-inch long, ½-inch drive breaker bar and on some bolts, the whole car moved when cracking them. For really tough ones, put a long pipe on the end and use your whole body. I needed to do this to break the crankshaft bolt – one of the most notorious around!
- Blow Torch: Don’t be stupid when playing with fire. While this method almost always works, I never use it first. For one thing, if you’re under a car, with brake lines, fuel lines, oil and a haze from the PB Blaster you just sprayed everywhere – you’re asking to go boom. You can also damage the bolt or melt plastic and rubber parts. If you do move forward, don’t heat the fastener too long. 30 seconds (or less) should be plenty.
Rounded or Stripped Bolts:
Here are the steps to take AFTER you’ve rounded the bolt off. Hopefully avoidable if you follow the tips above. However, if you’re here from Google search, it’s probably too late for that.
- Steel wool: Here’s one I came up with in a moment of frustration (although I doubt I’m the first to use it). Stuff some steel wool in a 6-point socket and lightly tap it onto the bolt with a rubber mallet. It might snug it enough to crack it. You need to do this early on, while most of the shape is still there. If I’m getting some torque, but slipping off, that’s when I do this.
- Cold chisel (or nut cracker): The only affordable nut cracker I found was way too bulky to use under the car. Frankly, it was too bulky to use about anywhere that seemed useful. So, I’ll wager in most cases, you’ll turn to the chisel. This method is straight forward. Whack the chisel against the nut at a ninety degree angle to split it. This can take a lot of elbow grease so get a heavy hammer and a sharp chisel. If you can access both ends of the fastener, go about 75 percent of the way through the nut and turn the bolt head; it might free it with less risk of thread damage to the bolt. This is a last resort method because there is a real risk of damaging the thread. Not good if it’s a tapped component like a transmission post. I did it on an engine mount on the Subaru and did dent the thread ever so slightly. Luckily, running die over it restored it enough to get a new bolt on. This method also doesn’t do any read good if the stripped fastener is a bolt – in which case proceed to step four.
- Extractors: They make bolt extractors, which are basically six-point sockets with sharp internal edges that grab the rounded fastener. In my XP, these were way too costly. If you wrench for a living, I’m sure they’re a good investment, but a crummy Autozone pack of 3 bolt extractors was like $30. That’s a lot for something you may never need again on your own car. Still, if protecting the stud is essential, this may be the route to go. I would suggest buying them as one-offs online if you have a need and a project that isn’t on deadline.
- Dremel: Last, least and IMO – not at all. If YOU want to cut the fastener off, go for it. But wear you’re ANSI glasses. Also, if you just sprayed PB Blaster all over… stop. This method will throw off a lot of sparks. Lastly, cheap cutting discs can break and throw sharp, fast-flying shrapnel at you. If ruining the bolt is unavoidable, just use the chisel.