Remove a Stripped Head Bolt on a Car
Head bolts, also called cylinder head bolts, are car engine bolts that are used to secure the engine's cylinder head to the engine block. Head bolts must be tightened correctly in order to create a leak-free seal between the cylinder head and the block, and the threads are generally coated with a fixative to keep them stationary. For this reason, it is not unusual to strip head bolts when you try to loosen them in order to work on your car engine. If you have a stripped head bolt on your car, there are several ways you can go about removing it and some may work better than others, depending on your car make and model. Follow these instructions for how to remove a stripped head bolt on a car.
Contents
Steps
Removing a Bolt with Common Tools
- Remove a bolt that is stripped by clamping a wrench to the bolt head. This method only works if the car head bolt is clearly accessible.
- Use a small, high-quality pipe wrench.
- Grip the exposed portion of the stripped head bolt tightly with the wrench.
- Pull the wrench upward while it is clamped to the bolt.
- Whack the wrench with a hammer to loosen the bolt, making it possible to remove the bolt.
- Use a center punch and a hammer to loosen and remove a bolt. This method is ideal for hard-to-reach bolts.
- Hold the center punch to the side of the bolt head, in the middle, at a 90 degree angle from the bolt shaft (parallel to the bolted surface).
- Use a heavy hammer to knock the center punch into the bolt head in order to create an indentation.
- Fix the center punch into the indentation at a different angle and whack it again with the hammer. You should be able to knock the stripped head bolt loose with a few strong whacks.
- Buy a tool that is specifically designed to remove a bolt that has been stripped. This kind of tool has special teeth that grip into stripped bolt heads and bite more and more deeply as you tighten the bolt, ultimately providing enough of a grip for you to remove the stripped bolt.
- Drill out the stripped head bolt.
- Use a 1/4 inch (0.635 cm) drill bit to drill a 1 inch (2.54 cm) deep chamber in the center of the bolt. This will be your guide for subsequent drilling, so do your best to keep the drill straight as you drill.
- Replace the 1/4 inch (0.635 cm) drill bit with the next size up and drill into the pre-drilled guide hole.
- Continue to drill into the hole in the bolt, 1 size up at a time, until you have stripped out enough of the old bolt to remove the threads.
- Use a store-bought screw extractor kit to remove the rest of the car head bolt.
- Take your car to an auto shop if you cannot remove a stripped bolt using these methods.
Torch and hammer removal
Be aware that this method is not suitable for aluminum heads, which it will likely permanent damage or destroy. It is effective for other head bolt metals, and for other stripped bolt applications.
- Find a socket that is one size smaller than the bolt originally was.
- With a torch, heat the bolt head until it is cherry red.
- Quickly hammer the smaller socket onto the bolt head. Allow it to cool before trying turn.
Tips
- Spray a penetration fluid around the car head bolt before attempting to loosen it to aid in the removal process.
Warnings
- Do not ever use a worn or rounded socket to remove a car head bolt. By only using new, high-quality tools, you are likely to avoid having a stripped bolt altogether.
