Tightening a Spinning Bolt: Troubleshooting and Solutions

When replacing a bolt, especially for critical components like an alternator, encountering a spinning bolt can be frustrating. If you've replaced the bolt, rethreaded the hole, and are still facing the issue, it likely indicates a problem with the bolt, the hole, or both. Here are some steps to diagnose and resolve the issue.

Identifying the Problem

First, consider the type of bolt and hole you are working with.

Check the Bolt and Hole

Inspect the Bolt

Ensure the bolt is the correct size and thread pitch for your application. A damaged or worn bolt may not grip securely. If the bolt is stripped or worn, it won't hold in place properly.

Inspect the Hole

Look for signs of stripping or damage in the threaded hole. Stripped threads mean the bolt can't grip effectively. If you find any damage, it will need to be repaired.

Repairing Stripped Threads

For significant damage, you may need to repair the threads in the hole. Here are the steps for using a thread repair kit, such as a Helicoil:

Drill out the damaged threads to a specified size.

Tap new threads for the Helicoil insert.

Insert the Helicoil, which provides new threads for the bolt to grip.

Using Thread-Locking Compound

If the threads are still somewhat intact but not holding well, a thread-locking compound such as Loctite can help. This can enhance the hold and prevent the bolt from spinning or coming loose.

Using a Larger Bolt

If the hole is too damaged for the existing bolt, consider using a larger bolt. However, you will need to re-tap the hole to the new size. Make sure this is compatible with the alternator mount.

Alternative Fix: Nut and Bolt Setup

If feasible, use a longer bolt that passes through the mounting point and secure it with a nut on the other side. This can provide a more secure hold and solve the spinning issue.

Consulting a Professional

If you're unable to resolve the issue on your own, consider consulting a mechanic or a professional with experience in automotive repairs. They can provide guidance and perform the necessary adjustments or repairs more effectively.

Conclusion

By following these steps, you should be able to identify and resolve the issue of a spinning bolt. Remember, the key is to ensure proper matching of bolts and holes, and to take appropriate measures if you encounter stripped threads or other issues.