how to remove a rusted bolt

Know-How Notes: How to Remove a Rusted Bolt

Rusted bolts stink. It doesn’t matter if the car is just a few years old or 50, there will always be rusted or seized nuts and bolts somewhere on the car. Murphy’s Law dictates that you will find those bolts when you are in the biggest hurry to complete a project. There are many ways to remove a rusted bolt. For this article, we are focusing on one in particular- Freeze-Off from CRC.

Unlike other penetrating oils, Freeze-Off adds the unique feature of hyper-cold to shock the offending part, breaking the rust bond, allowing the bolt to come out. This is achieved through the propellant and the penetrating oils. The oils are designed to dissolve rust, gum and corrosion. Freeze-Off also displaces water to prohibit future corrosion.

We had a 2009 Dodge Challenger in the shop that needed a plug removed from the exhaust. The exhaust is stainless steel, but the plug is steel. Any time you have differentiating metals, corrosion and seized threads are a very real problem. This plug was locked tight.

Stainless steel bung and a mild-steel plug mixed with high heat is a recipe for seized threads.

Stainless steel bung and a mild-steel plug mixed with high heat is a recipe for seized threads.

 

With the exhaust cool, we sprayed the Freeze-Off on the plug and allowed it to sit for 5 minutes.

We sprayed the Freeze-Off while the exhaust was cool and left it to sit. On mildly rusted threads, this should do the trick.

We sprayed the Freeze-Off while the exhaust was cool and left it to sit. On mildly rusted threads, this should do the trick.

 

The plug uses an Allen-wrench, which we employed along with an Ingersoll-Rand cordless impact wrench. The plug was still locked on solid.

We tried an impact wrench to knock the plug loose, but it was not budging. Time to get more serious.

We tried an impact wrench to knock the plug loose, but it was not budging. Time to get more serious.

 

Because the Freeze-Off has the ability to shock the part, we stepped up our game and brought out the propane torch. By heating the outside of the threads, we can expand the metal, hopefully loosening the plug. We got the part up to 366 degrees.

A propane torch was used to heat up the bung, this will expand the metal.

A propane torch was used to heat up the bung, this will expand the metal.

 

We checked the temp with an IR thermometer. 366 degrees. Don't touch it!

We checked the temp with an IR thermometer. 366 degrees. Don’t touch it!

 

Before we try to turn the plug, we applied more Freeze-Off. This does a couple of things- first, the heat will pull the penetrating oils into the threads through wicking action. Secondly, by spraying just the plug itself, the Freeze-Off will cool the part quickly, providing even more shock to the threads to break the rust. With the outside still hot and the plug cold and shrinking, the bond should break fairly easy. Be careful, as this will create a lot of smoke.

Now for the smoke show. Spraying the Freeze-Off on the plug while it is hot does two things- wicks the penetrant into the threads and shocks the plug with it's cold reaction, shrinking the metal of the plug while the threads stay hot.

Now for the smoke show. Spraying the Freeze-Off on the plug while it is hot does two things- wicks the penetrant into the threads and shocks the plug with it’s cold reaction, shrinking the metal of the plug while the threads stay hot.

 

Using the Allen wrench and a cheater bar for additional leverage, the plug broke free. Now the project can be finished up. Remember to use anti-seize on high-heat threads and anytime differential metals are bolted together.

We put an Allen wrench on the plug with a piece of pipe as a cheater bar and gave it a push. The plug popped loose.

We put an Allen wrench on the plug with a piece of pipe as a cheater bar and gave it a push. The plug popped loose.

The plug was then tossed for a new O2 sensor. Anytime you have different metals going together, you need anti-seize.

The plug was then tossed for a new oxygen sensor. Anytime you have different metals going together, you need anti-seize.

Check out all the chemical products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information how to remove a rusted bolt, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

about author

Jefferson Bryant

A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.

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