How To Remove Broken Valve Cover Bolt

A broken valve cover bolt is a frustrating, but common, automotive repair. Removing a broken bolt, especially one located in a relatively inaccessible area like a valve cover, can seem daunting. However, with the right tools, techniques, and a bit of patience, you can often extract the broken bolt yourself, saving significant money on professional repairs.

Why Removing a Broken Valve Cover Bolt Matters

Ignoring a broken valve cover bolt can lead to several problems, ultimately impacting your engine's performance and potentially causing more serious damage. Here's why addressing this issue promptly is crucial:

• Oil Leaks: The primary function of the valve cover gasket, secured by these bolts, is to create a tight seal preventing oil leaks. A broken bolt compromises this seal, leading to oil seepage. Oil leaks not only make a mess but can also drip onto hot engine components, creating a fire hazard or emitting unpleasant odors.
• Reduced Engine Performance: Oil leaks can lower the engine's oil level, leading to reduced lubrication and increased wear on engine parts. This can manifest as decreased power, rough idling, and even potential engine damage over time.
• Vacuum Leaks: In some engine designs, the valve cover also plays a role in the engine's vacuum system. A loose or improperly sealed valve cover due to a broken bolt can create a vacuum leak, disrupting the air-fuel mixture and leading to poor engine performance, including hesitation, stalling, and reduced fuel economy.
• Engine Damage: Prolonged oil leaks can contaminate other engine components, such as belts and hoses, causing them to deteriorate prematurely. Furthermore, severe oil leaks can lead to engine overheating due to insufficient lubrication, resulting in catastrophic engine failure.

In short, neglecting a broken valve cover bolt can lead to a cascade of problems. Addressing it promptly ensures your engine runs smoothly, efficiently, and prevents potentially expensive future repairs.

How to Choose the Right Removal Method & Tools

Several methods exist for removing a broken valve cover bolt, and the best approach depends on factors such as the severity of the break, the amount of the bolt protruding, and your comfort level with various tools and techniques. Here's a breakdown of common methods and the tools you'll need:

1. Easy Out (Screw Extractor) Method

This is a popular and often effective method. Easy outs are hardened steel tools with a reverse thread design. They bite into the broken bolt and, as you turn them counterclockwise, they grip the bolt and ideally back it out.

• Screw Extractor Set (Easy Outs): Choose a set with various sizes to match the bolt you're trying to remove.
• Drill: For creating a pilot hole in the center of the broken bolt.
• Drill Bits: A selection of drill bits to start with a small pilot hole and gradually increase the size as needed.
• Tap Handle or Wrench: To turn the screw extractor.
• Penetrating Oil: To help loosen the corroded bolt. Apply liberally and allow it to soak for several hours or even overnight. WD-40 Specialist Penetrant is a good choice.
• Center Punch (Optional): To create a starting point for the drill bit, preventing it from wandering.

When to Use: This method is best when the bolt is not completely seized and has a relatively clean break. It's also suitable when there's some portion of the bolt protruding that you can drill into.

2. Pliers/Vise-Grip Method

If a significant portion of the bolt is protruding, you might be able to grip it directly with pliers or vise-grips and twist it out.

• Vise-Grips or Locking Pliers: Choose high-quality vise-grips with sharp teeth for a firm grip.
• Penetrating Oil: Absolutely essential to loosen the bolt.
• Heat Gun or Torch (Optional): Applying heat can help break the bond between the bolt and the surrounding metal. Use caution and avoid overheating the area.

When to Use: This is the simplest method and works best when a good portion of the bolt is exposed and not excessively corroded.

3. Left-Handed Drill Bit Method

Similar to the easy-out method, but instead of using an extractor, you use a left-handed drill bit. As the drill bit bites into the bolt, the reverse rotation may be enough to unthread it.

• Left-Handed Drill Bit Set: Ensure you have the appropriate size for the bolt.
• Drill: A variable-speed drill is ideal.
• Penetrating Oil: To help loosen the bolt.
• Center Punch (Optional): For creating a starting point for the drill bit.

When to Use: This method can be very effective, especially if the bolt isn't heavily seized. The vibration and reverse rotation of the drill bit often help break the bolt free.

4. Welding a Nut Method

This method involves welding a nut onto the broken bolt, providing a new surface to grip and turn.

• Welder: A MIG or TIG welder is recommended.
• Nuts: Choose a nut that's slightly larger than the bolt's diameter.
• Welding Helmet, Gloves, and Other Safety Gear: Welding involves high heat and requires proper protection.
• Penetrating Oil: While not strictly necessary, it can still help.

When to Use: This method is ideal when the bolt is broken off flush or slightly below the surface. It requires welding skills and equipment but can be a very reliable solution.

5. Professional Extraction

If you've tried the above methods and are still unable to remove the broken bolt, or if you're uncomfortable with any of these techniques, it's best to seek professional help. A qualified mechanic has the tools, experience, and expertise to safely and effectively remove the broken bolt without causing further damage.

Real-World Owner Experiences

Many DIY mechanics have encountered the dreaded broken valve cover bolt. Here are a few snippets of advice and experiences from online forums and communities:

• "Penetrating oil is your best friend! Don't skip this step. Soak it, soak it again, and then soak it some more." - This highlights the importance of penetrating oil in loosening corroded bolts.
• "Start with a small pilot hole when using an easy out. It's easier to center and gradually increase the size than to start with a large hole and risk damaging the threads." - This emphasizes the importance of precision and patience when drilling.
• "If the easy out breaks off inside the bolt, you're in for a real headache. They're incredibly hard to drill out. Be careful and don't apply too much force." - A word of caution about the fragility of easy outs.
• "Welding a nut worked great for me! Just make sure you get a good weld to both the bolt and the nut." - A positive experience with the welding method.
• "Don't be afraid to ask for help if you're stuck. Sometimes a professional is the best option." - Reinforces the idea that knowing your limitations is key.

Frequently Asked Questions (FAQs)

Here are some common questions related to removing broken valve cover bolts:

Q: What if the easy out breaks inside the broken bolt?

A: This is a common and frustrating problem. Easy outs are very hard, making them difficult to drill out. If this happens, you may need to try welding a nut onto the broken easy out (requires significant welding skill), or as a last resort, seek professional help. A machine shop may be able to use an EDM (Electrical Discharge Machining) to remove the broken extractor.

Q: Can I drive my car with a broken valve cover bolt?

A: While you might be able to drive a short distance, it's not recommended. As mentioned earlier, a broken bolt can lead to oil leaks, reduced engine performance, and potential engine damage. It's best to address the issue as soon as possible.

Q: How do I prevent valve cover bolts from breaking in the first place?

A: Overtightening is a common cause of broken valve cover bolts. Always use a torque wrench and refer to the manufacturer's specifications for the correct torque value. Also, use anti-seize compound on the bolt threads to prevent corrosion and make future removal easier.

Q: What if the bolt breaks off flush with the engine head?

A: A flush break makes extraction more challenging. Welding a nut is often the best approach. Alternatively, a screw extractor can be used, but it will require carefully drilling a pilot hole in the exact center of the bolt. This requires a steady hand and sharp drill bits.

Q: How much does it cost to have a mechanic remove a broken valve cover bolt?

A: The cost can vary depending on the complexity of the job and the mechanic's hourly rate. Expect to pay anywhere from $100 to $400 or more. The price will increase significantly if the bolt is deeply embedded or if the mechanic needs to remove other components to access the broken bolt.

Q: What type of penetrating oil is best?

A: Several penetrating oils work well. PB Blaster, Liquid Wrench, and Kroil are popular choices. WD-40 Specialist Penetrant is also a good option. Apply the oil liberally and allow it to soak for as long as possible, ideally overnight.

By understanding the potential problems caused by a broken valve cover bolt, selecting the appropriate removal method, and following these guidelines, you can increase your chances of successfully extracting the broken bolt yourself and saving money on costly repairs. Remember to prioritize safety, take your time, and don't hesitate to seek professional help if needed.