How to remove a broken bolt from an engine?

Learn effective techniques for removing broken engine bolts, including the use of extractors, proper tools, and safe methods to avoid damaging parts.

You probably know how frustrating it can be to deal with a broken bolt. Even removing old bolts from an engine is a challenge, due to rust, corrosion, and damage from extreme heat. Now, imagine when the screw breaks completely.

This usually means the hex head has disappeared, leaving you without something to grip with your ratchet or wrench. The result? An almost impossible task without the right tools and techniques.

There are effective ways to remove broken bolts from an engine. In this article, we’ll explore five methods that range from simple fixes to more advanced techniques.

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Apply heat and use pressure clamps

If the screw still has part of its shaft exposed, one of the first methods to try is to apply heat and use vise clamps or pliers to remove it.

Heat helps to expand the metal, freeing the bolt from rust and corrosion. A popular source of heat is an oxyacetylene torch, but you can also use a propane torch or even a butane lighter in emergencies.

Steps for the method:

Choose a tool to heat the screw. Be sure to protect adjacent components, such as rubber hoses or belts, which could be damaged by the heat.
Heat the screw until it is red hot.
Use vise clamps or pliers to firmly grip the hot shaft.
Try twisting the screw in the direction of loosening.

Important Note: This method only works if part of the screw is exposed. If it broke off close to the hole, you'll need to try another approach.

Use hammer and chisel

Once a significant portion of the broken screw has been exposed, you can try to remove it with a hammer and chisel. This technique is quick and easy, and is ideal for situations where more sophisticated tools are not available.

Necessary materials:

Hammer (preferably a small mallet);
Chisel or pry bar with impact tip;
Penetrating oil.

How to:

Apply penetrating oil to the screw shaft.
Position the tip of the chisel on the end of the screw, angling it so that it hits in the loosening direction.
Tap the chisel lightly to create an initial mark, preventing it from slipping.
Gradually increase the force, applying firm, controlled blows until the screw begins to turn.
Use pliers or vise grips to complete the removal.

This method is especially effective for larger screws and can be tried before resorting to more advanced techniques.

Weld a nut onto the exposed shaft

For those who have access to welding equipment, this method is highly effective. It involves welding a nut to the shaft of the broken bolt, allowing you to remove it with a ratchet or wrench.

What do you need:

MIG, arc or stick welder;
Nut compatible with the size of the broken shaft;
Wire brush or grinder to clean the surface before welding.

Procedure:

Clean the bolt and nut to remove dirt, grease or rust.
Place the nut over the broken axle and weld it in at least two places.
Wait until the solder has cooled and is firm.
Use a ratchet or wrench to turn the nut and remove the bolt.

This method requires more technical skills, but is highly reliable for complicated situations.

Drilling with a left-hand thread drill bit

If the above methods fail, an alternative is to use a left-hand thread drill bit. This tool, also known as a reverse drill bit, can help loosen the screw while you drill.

Necessary materials:

Punch tool;
Hammer;
Drill;
Left hand thread drill.

Steps to execute:

Use a punch tool to create a mark in the center of the screw shaft.
Align the left drill bit with the mark and begin drilling carefully.
If necessary, start with a smaller drill bit to create a pilot hole.
Continue drilling until the bit bites into the screw and begins to turn it out.

This method is efficient, but requires a lot of precision when positioning the punch and drill.

Use an extraction tool

When none of the above techniques work, the final solution is to use a screw extractor. This specialized tool is designed to safely and effectively remove broken screws.

What will you need:

Punch and hammer tool;
High quality drills;
Set of extractors.

How to proceed:

Use the punch tool to create an indentation in the center of the screw.
Drill a pilot hole with a small drill bit.
Gradually increase the diameter of the hole until it is slightly smaller than the extractor.
Insert the extractor into the hole and tap it lightly with a hammer to secure it.
Use a wrench to turn the extractor and remove the screw.

This method is considered the most advanced solution and is ideal for extreme situations.

When no method works

If none of the above techniques solve the problem, the only remaining option is to drill out the bolt shaft completely and re-drill the hole. This process is highly complex and should only be performed by professionals or those experienced in engine maintenance.

Steps to drill completely:

Create an indentation in the center of the screw with the punch tool.
Drill a pilot hole and gradually increase the diameter until the screw is completely removed.
Rethread the hole with a tap and die set suitable for the thread pitch of the new screw.

This procedure is laborious and risky, but it can save the component if all other methods fail.

With these five techniques and a workaround in hand, you can deal with broken bolts more efficiently and avoid future headaches. Choose the method that best suits your situation, and remember to always use the right tools to ensure the best result. Avoid improvising in more serious cases, as this can further damage the engine.

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José

#102287

22/12/2024 02:57

Never use solder when the screw breaks flush with the block, the heat from the solder will increase the hardness of the screw, preventing you from drilling it later.

How to remove a broken bolt from an engine?