I am having a tough time removing rusted bolts on a total restoration project. Can someone offer a lead on removing them? Thanks!
This is a question every car enthusiast has asked themselves. “What is the best way to remove rusty bolts?”
Basically there are two tried-and-true methods for unbolting rusty fasteners: penetrating oils and heat. Let’s discuss penetrating oils first.
Many enthusiasts quickly grab a can of WD-40, hose down the bolt, then try to turn it two minutes later, usually without success. Remember, those bolts have had 30+ years to rust together. Releasing them is seldom that easy.
In a published article in Machinist Workshop Magazine, they tested some commercially available penetrating oils on a group of nuts and bolts they had scientifically rusted to a uniform degree in a saltwater solution.
The fasteners were treated with a variety of commercially available penetrants, and the measured torque required to loosen them was recorded.
The breakout torque required for:
- Nothing = 516 ft. lbs.
- WD-40 = 238 ft. lbs.
- PB Blaster = 214 ft. lbs.
- Liquid Wrench = 127 ft. lbs.
- Kano Kroil = 106 ft. lbs.
- 50/50 blend of ATF and Acetone = 50 ft. lbs.
As you can see by the results of their test, the homebrew concoction of automatic transmission fluid and acetone worked best. But also keep in mind that acetone is very flammable and must be dispensed from a sealed metal container, similar to the old oil squirt cans. From my own experience, this solution works very well and seems to work a little better if you use synthetic ATF. I have also used Kroil for years, and because it’s less volatile than the homebrew, it is often my first choice.
Don’t rush it. When I have several bolts to remove that I know are going to give me trouble, I will often spray them down several times over the course of a couple of weeks before even trying to turn them.
If all else fails, I use heat—and I mean red hot! Simply getting a bolt hot with propane or gas seldom does the trick. It’s time to break out the oxy/acetylene torch and heat up the nut so it expands away from the bolt. Then, before it cools, wrench it off. Of course, if it’s close to anything that could combust (i.e. gas tanks, fiberglass bodies, etc.), don’t try it! Instead, spray on more penetrating oil and try again later.
There is another method to supply the heat directly to the bolt without affecting the surrounding area, and that is using inductive heating. While relatively new on the market, the inductive heaters get the job done with a lot less risk than using an open flame. However, their $500-$600 price point will put it out of range for many hobbyists.
Cautionary notes: Always wear eye protection when working with solvents. Penetrating oils contain solvents, so it is a good practice to wear rubber gloves to protect yourself from them. Always use acetone in a well-ventilated area as it is highly volatile. Never combine the use of penetrating oils and heat, as the fumes can be hazardous to your health. When using a torch to heat bolts, be aware of any other flammable components nearby and have a fire extinguisher ready.
I hope this helps, and if all else fails, check out this great video to see Brent demonstrate how to remove broken bolts using an easy out.