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How to Remove a Broken Bolt from an Engine Block

If you’re learning how to remove a broken bolt from an engine block – and don’t do it right – you could be putting yourself and others in danger. Learning the right way to remove broken bolts will save you both time and money, and reduce the chance of a deadly or costly breakdown.

Our guide looks at how you can remove broken bolts from different parts of the engine, and different materials. You’ll know which tools to use, how to use them, and the exact steps you’ll need to follow!

Let’s get into the guide.

How to Remove a Broken Bolt from an Engine Block

This section looks at the steps to follow to remove a broken bolt from various engine parts and material types. Here are all the tools you’ll need:

  • Hardened steel centering the punch
  • Hammer
  • Metal-cutting drill bit (1/8th inch or smaller)
  • Bolt remove that match the hole size
  • Wrench
  • Drill
  • Heating torch
  • Sturdy pliers

Have these tools handy before moving on.

Step 1: Center Punch the Broken Bolt

Use the hardened steel center punch to punch a hole exactly in the center of the broken bolt. Use a hammer to hit the punch and make the hole. This will help guide the drill bit.

Step 2: Drill a Starting Hole

Use the drill and drill bit (1/8th inch or smaller) and make a hole. Keep it as straight as you can and in-line with the direction of the bolt.

Step 3: Buy the Bolt Remover

You’ll need to measure how wide the threads of the bolt are. Take this number to your local hardware store and buy the matching size bolt remove.

A bolt remove threads into the bolt in the opposite direction, letting you unscrew and remove it.

Step 4: Insert the Bolt Remover

Read the bolt removers packaging to see if you need to make the hole wider. Do so if you need to.

Once the hole is the right size, screw in the remover until it reaches its taper.

Step 5: Remove the Bolt

When the taper is reached, the bolt will begin to unscrew and come out.

Use the wrench to put pressure on the remover by screwing counterclockwise. This will slowly nudge the broken bolt out.

How to Remove a Broken Bolt from Aluminum

The issue here is that once steel and aluminum get married, it tends to be for life! It can be tiresome to remove the broken bolt, but here’s a solution that worked for us:

  • Weld a piece of metal onto the bolt – this will be easier if some of the bolts are already sticking out
  • If the bolt is flush with the aluminum then weld a smaller piece first
  • Let the weld cool
  • Take a wrench and try to unscrew the bolt as you normally would

If these steps don’t work for you, try this:

  • Drill a pilot hole into the broken bolt
  • Gradually widen the hole carefully until the screw can be manually taken out
  • You can heat the surrounding aluminum for faster results

How to Remove a Broken Bolt from Exhaust Manifolds

The results you get here will depend on how lucky you got. If the bolt broke off with some shaft still exposed, you’re in luck.

All you’ll need to use is a set of sturdy pliers to grip the shaft. Manually work the bolt until it comes out.

If the bolt broke off flush, you can weld a nut head onto the bolt. Let it cool off and harden, then try to remove the bolt as usual.

If the bolt has broken off and seized deep inside the threads, you’re going to need to drill into it. Follow the steps from the “how to remove broken bolts from engine blocks”.

This should work fine, although it’s going to take loads of time and manual effort to get it done.

How to Remove a Broken Bolt without Drilling

You’ll need a welding machine, some nut heads, and a wrench to remove a broken bolt without drilling.

These steps will only work if the bolt broke off flush, or there is still some shaft visible.

Here is what you need to do:

  • Weld one of the nut heads to the shaft of the broken bolt
  • Let the weld cool and harden
  • Use the wrench to grip the welded nut head
  • Unscrew the bolt as you usually would

Follow these steps if you want to know how to remove a broken bolt without a drill.

How to Remove a Broken Off Bolt

When luck isn’t on your side, the bolt will break off deep inside the threads. It can also break at an angle. Here’s a summary of what to do with different types of breaks. When some shaft is still visible, you can try these methods:

  • Use a set of pliers to manually unscrew the bolt
  • Weld a nut head to the shaft
  • Drill into the bolt and use a bolt remover

When the bolt breaks flush with the surface, try these methods:

  • Welding some metal to the bolt (be sure not to weld to the surrounding surface, or you’ll make your job even harder) and unscrewing it as normal.
  • Drilling into the bolt, making the hole wider and wider until it can be picked out
  • Drilling into the bolt and using a bolt remover

When the bolt breaks of deep in the threads or at an angle, try these:

  • Drill into the bolt if the break is not at an angle – use a bolt remover
  • Drilling into the bolt, making the hole wider and wider until it can be picked out
  • Heating the surrounding metal and drilling into the bolt, using a bolt remover to unscrew it

Final Thoughts

That’s it for our guide! Well done for taking the time to get through it.

All that’s left is for you to get some experience and practice. Now that you know how to remove a bolt from an engine block, you’re ready to put what you’ve learned into practice – you’ll be removing bolts like a pro in no time!

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