A broken bolt can be a frustrating obstacle, whether it’s stuck in an engine, machinery, or household equipment. Removing it requires patience and the right tools to avoid damaging the surrounding material. Several methods can be used depending on how deep the bolt is lodged and whether it has a stripped or rusted surface. Here is how to remove a broken bolt.
Assessing the Situation
Before attempting removal, determine how much of the bolt is exposed and whether it is rusted or broken flush with the surface. If part of the bolt is sticking out, it may be easier to grip and extract. If it’s broken off inside the hole, specialized tools will be needed.
Using Locking Pliers or a Wrench
If a portion of the broken bolt is visible:
- Grip the Bolt Tightly: Use locking pliers (vise grips) or a wrench to get a firm grip on the bolt.
- Apply Penetrating Oil: Spray WD-40 or a similar penetrating oil around the bolt and let it sit for a few minutes to loosen any rust or debris.
- Turn Slowly: Try turning the bolt counterclockwise to remove it. Applying steady pressure rather than jerking movements reduces the risk of further breakage.
Using Heat to Loosen the Bolt
If the bolt is stuck due to rust or corrosion, heat can expand the metal and break the bond:
- Use a Propane Torch: Heat the area around the bolt (not the bolt itself) for about a minute.
- Cool It Down Quickly: Apply penetrating oil immediately after heating. The expansion and contraction can help break the bolt loose.
- Attempt Removal: Use pliers or a wrench to turn the bolt while it’s still warm.
Drilling and Extracting the Bolt
For bolts that have broken flush with the surface:
- Mark the Center: Use a center punch to create a small indentation in the middle of the broken bolt.
- Drill a Pilot Hole: Select a drill bit smaller than the bolt’s diameter and carefully drill straight down into the broken bolt.
- Use a Bolt Extractor: Insert an extractor tool (easy-out) into the hole and turn it counterclockwise using a wrench. The reverse threads will grip the bolt and pull it out.
- Try Left-Handed Drill Bits: If an extractor is not available, using a left-hand drill bit may loosen the bolt enough to remove it as it drills.
Tapping and Retapping the Threads
If the bolt is completely seized or the threads are damaged:
- Drill Out the Bolt Completely: Use a drill bit slightly smaller than the bolt’s diameter to remove it entirely.
- Re-Tap the Hole: Use a tap and die set to clean or restore the threads before inserting a new bolt.
Preventing Future Broken Bolts
To avoid dealing with broken bolts in the future:
- Apply anti-seize lubricant before installing bolts in high-stress areas
- Avoid overtightening, which can cause bolts to snap
- Regularly inspect and replace corroded or weakened bolts before they fail
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