How to Remove Broken Bolts from Engine Block: Easy Methods

Learning how to remove broken bolts from engine block is a very important skill because the longer the bolts remain there, the more you will be unable to use your car. Depending on the type of bolt and how it snapped, there are different methods you can use to remove it.

How to Remove Broken Bolts from Engine Block

You can decide to drill it, use welding or use two nuts to remove the existing snapped nuts. It is a good idea to try out some methods before removing the engine and taking it to the mechanic, so continue reading our complete guide below to know more and choose the correct method for you.

How To Remove Broken Bolts from Engine Block in Your Car?

You can remove broken bolts from an engine by using two nuts. If you still have a reasonable length of the snapped bolt left on the block, you can use this method first. Keep in mind that if the bolt breaks off because it seized, avoid removing it forcefully.

A good method would be to soak it in a rust remover and leave it for up to 10 minutes – no longer. It would also be a decent idea to heat the remaining bolt to loosen it a bit. To do this you can use a heat gun, torch lighter, or blow torch.

1. Get the Required Tools

Here are the tools that you need to remove snapped bolts from a block:

Getting Required Tools To Remove Broken Bolts

  • Two nuts that are the same size as the snapped bolt.
  • Wrenches.
  • Rust remover spray.
  • Blow torch, heat gun, or torch lighter.

2. Follow These Steps

Follow these steps to remove the bolts with two nuts:

  1. Use the rust remover spray to soak the snapped bolt and leave it for up to 10 minutes.
  2. Place the two nuts on the snapped bolt, one after the other.
  3. Tighten the nuts on the bolt against each other. The top one should be tight, while the bottom one should be unfastened.
  4. Carefully and slowly turn the bottom nut to remove the bolt.
  5. You should be doing it slowly, but if it feels like it is going to break, you need some heat. Apply heat to the bolt so, loosen it up, and turn the bottom nut again. It should come loose now.

How To Remove Broken Bolts from Engine Block by Welding?

You can remove broken bolts from the block by welding if you have a minimum of five millimeters of the bolt remaining on the engine. You also need a welding machine, and if you cannot use it, you can ask a friend or a welder to help you do this.

This is the easiest and quickest method on our list because it allows you to completely melt the bolt.

Removing Broken Bolts from Engine Block by Welding

Once you melt it, it would be easy to remove it and even weld a nut on top. You can decide to use this alone instead of the method of using two nuts.

1. Required Tools

You should get these tools to use this method in removing snapped bolts:

  • A TIG or CO2 welding machine.
  • Welding equipment like masks and gas tanks.
  • Wrenches.
  • A nut that is the same size as the snapped bolt.

2. Steps to Follow

  1. Follow the steps below to remove the snapped bolts with welding:
  2. Set up your welding machine and keep all the safety issues in mind.
  3. Tighten the nut on the snapped bolt or just rest it on it if the snapped bolt is not long enough. You can hold it with some pliers.
  4. Use the welding machine to weld the inside of the nut to the bolt. You should tack weld the nut so you do not overheat the bolt and make it melt.
  5. After it has been welded, leave it for up to 20 seconds, then use the wrench to remove the bolt. It would be loose with the heat and easy to remove with the nut on top.

How To Remove Broken Bolts from Engine Block by Drilling?

You can remove broken bolts from the block by drilling and with a bolt extractor if the snapped bolt is on the same level as the engine. If the bolt is too deep in, you need to drill it, and there are two ways you can do so.

Removing Broken Bolts from Engine Block by Drilling

For one, you should make use of a screw extractor. This is an effective tool that allows you to extract bolts, but you need to be careful while doing this because if it breaks, you will have to figure out a way to remove not only the bolt but also the extractor.

You can reduce the chances of that happening by using a center punch and hammer to hit the extractor. But if you hit it too hard, the extractor can break into different pieces. You can also take the engine and extractor to a machining shop or use a Dremel to cut through it.

Another way to extract by drilling is with a Torx bit. You can punch the Torx bit into the hollow bolt, but you should be careful not to let it break. It is important to be careful because if it breaks, you will not be able to drive your car for a while.

1. Required Tools

If you want to use drilling, these are the tools that you need:

  • Center punch.
  • Bolt extractor or Torx bit.
  • Hammer.
  • Drill.
  • Correct size hardened drill bit.
  • Vice grips, adjustable wrench, or tap wrench, which can hold and twist the extractor.

2. Steps to Follow

Follow the steps below to use a drilling and extractor to remove a snapped bolt.

  1. With the punch, mark the center of the bolt to prevent the drill from wandering and damaging the thread.
  2. Use hardened drill bits that has a smaller diameter to drill the bolt.
  3. The drill bit should be big enough to damage the thread. For instance, if you have an 8mm bolt, you should use a 6mm drill.
  4. Punch the Torx bit or the bolt extractor into the bolt.
  5. Turn the drill slowly while applying more and more force. If you feel like it is going to break, then you should stop.
  6. If it is too tight to remove, spray some rust remover or use a blow torch to heat it. Then, try again to turn the bolt.

How to Know Which Method You Should Be Using?

The method for removing cracked bolts that you use depends on how deep the bolt is. If you still have more inches of bolts left on the block, you can use the two bolts or welders. But if the snapped bolt is too flat, consider drilling or an extractor.

There are two main reasons why the engine bolt can break: if it broke when trying to remove it or if you over-tightened it. In the best-case scenario, only the bolt head will break off. This will give you up to one inch of thread remaining. You can use two bolts to remove it, and you will not require any special tools. It is important to be careful in removing it to make sure you do not do any more damage..

In the second-best scenario, you will have about half an inch of the old bolt on the block still sticking out. If you still have this length of bolt on the engine, you should work with a welding machine. This is better than having the snapped bolt flat against the block, as this is the worst-case scenario.

In the worst situation, the bolt will be so snapped that it will be levelled with the block. In this case, you will even be able to touch the bolt or never mind do anything with it. If this happens, the only way you can fix the problem is by drilling and using an extractor. So, assess the level of damage on your block and choose the method that is ideal for you.

Frequently Asked Questions

– Why Does Heating Up a Bolt Work?

Heating up a bolt works because heat will expand the metal. When you apply heat, it will expand the bolt and the nut at different rates. This will also break the bonds of rust. Since it expands, it would be easier for you to extract it from the slot.

Heating Up Car Bolt

When you are using heat, it is better to avoid applying too much, or you will end up melting the bolt completely instead of just freeing it up. This is why you should use a heat gun, torch lighter, or blow torch and apply only a moderate amount of heat to the bolt.

– What Causes a Bolt To Break on an Engine Block?

A bolt can break on the block because of causes like tensile load, weakness, or corrosion. Tensile load means that the ends of the bolt were being pulled in different directions. After a while, the bolt on the engine can break because it has become too weak.

The bolt can break because it has corroded or rusted, and this is the main cause of bolts breaking. In your car, the bolt will constantly be touching chemicals or be affected by weather conditions. You should regularly check the bolts and remove them carefully before they being to corrode and break off.

– Can You Remove a Broken Bolt Without an Extractor?

Yes, you can remove a broken bolt without an extractor by applying a welder or using a Torx bit.

The Torx bit works similarly to an extractor, but you will punch it into the drilled hole instead of extracting it.

– Can You Drive If The Bolt From the Engine Block Gets Broken?

No, you cannot drive with a broken bolt on your engine. If you drive with a snapped bolt, you can expect an engine failure. If you have a snapped head bolt, you should remove it completely before driving. You can also take the engine to the mechanic shop.

– How Much Is The Fee to Extract a Broken Bolt From an Engine Block?

The fee to extract a broken bolt depends on the mechanic shop that you visit. Normally, it should cost between $60 and $100. If you cannot remove the bolt from the engine, you can visit the mechanic. When you do, ask them what method they will use.

Can the Methods Used to Remove Broken Bolts from an Engine Block also be Applied to Replace Broken Wheel Studs?

When faced with a broken wheel stud, you might wonder if the same methods used to remove broken bolts from an engine block can be applied to replace broken wheel studs. While the techniques used may share similarities, it’s important to understand that replacing a broken wheel stud requires specific tools and steps tailored to this task. The process involves removing the lug nut and wheel, extracting the broken stud, and installing a new one by hand or using a press. So, while some concepts may overlap, the methodology to replace broken wheel studs differs from removing broken bolts in an engine block.

What Are Some Easy Methods for Removing Broken Bolts from an Engine Block?

When dealing with a broken bolt in an engine block, there are a few reliable methods for removal. First, try using penetrating oil and allow it to soak overnight. If that fails, a bolt extractor or left-handed drill bit can do the trick. For stubborn bolts, welding a nut onto the broken piece can provide the necessary grip. Remember to proceed with caution, ensuring the engine block isn’t damaged in the process. Need more automotive advice? Check out the best tips for replacing camshaft sensors.

Can the Methods Used to Remove Studs from Tires Be Applied to Removing Broken Bolts from an Engine Block?

The process of removing studs from tires simplified offers valuable insights when it comes to removing broken bolts from an engine block. Both tasks involve dealing with stubborn fasteners that have become tightly lodged. By applying similar techniques and utilizing specialized tools, the challenging task of extracting broken bolts from an engine block can be approached with confidence and expertise.


Now that you know how to remove broken bolts from engine block, you can fix the problem when you notice that there is something wrong with your engine block.

Here is a rundown of what we covered in this guide:

  • You can remove the damaged bolt from the engine by using two nuts and making it weak with heat.
  • You can weld a new nut on the snapped bolt and use that to remove it completely.
  • Another method is through drilling and with an extractor.
  • The method that you use depends on how long the snapped bolt is.
  • A snapped bolt can happen because of weakness, corrosion, or a tensile load.

With this, you now know how to remove the snapped bolts from the engine. If you are unsure of how to fix this problem, you should visit a professional mechanic to help you with this.

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