How To Fix A Stripped Bolt Hole In An Engine Block

Going into fixing the engine block of your broken-down car is a piece of cake until you end up with the challenge of a stripped bolt hole.

A complete slip-up or a significant lapse in judgment can test your patience and turn a simple repair job into a troublesome task.

So, let’s find out how you can fix stripped threads in your engine block.

Stripped Thread in Aluminum Engine Block

Aluminum is a soft metal and usually is most widely used for engines due to its mechanical properties.

The bolt hole completely gets stripped due to the additional torque you may apply, possibly due to a faulty wrench or excess force.

To overcome such issues, repair manuals can always prevent a stripped bolt hole and provide you with the luxury of thread repair.

Most cases indicate that the bolt size might not adhere to the bolt holes, thus resulting in damaging the threads.

Most of the time, you’ll need to use a threaded insert that would ultimately allow you to make new threads into the stripped bolt hole.

Repairing jobs in such a case can be very troublesome, so, effectively, making the proper adjustments can be beneficial.

Especially in the case of aluminum block, the stripped hole can be a significant challenge because the original bolt could likely be damaged.

The female threads in the bolt hole are to be tightened using a torque wrench, but that is not the case every time, and it causes stripping of the hole.

Dealing with Partially Stripped Threads:

Many techniques are out there when you are dealing with partially stripped threads. At times, the threads would look fine physically but you may notice that they are slipping.

It might be because of the long bolt that may or may not fit correctly and cause permanent stripping.

Partially stripped threads can be challenging to deal with because of the hole size, and thread repair also requires a lot of attention. Making a new thread can be difficult because it could result in a damaged hole.

This calls for a repair job requiring you to make the hole bigger and use thread inserts to repair the hole.

Dealing with Badly Damaged Threads:

Badly damaged threads have been subjected to consistent loading from a long bolt and can contribute to developing a blind hole. Now, what is a blind hole?

It’s a hole developed contrary to the axis of the bolt hole, which can cause permanent damage to the thread.

Many challenges are there to overcome the bolt hole’s bottom end issues and tighten the clearance hole. A clearance oil must be used.

That’s because it can fill in the void left due to the increase in the diameter of the bolt hole. In this case, measuring the thread is a significant challenge and needs to be done by a proper thread measurement tool.

Many techniques are already on the market for fixing the damaged bolt holes, but badly damaged threads are not as easy to set as others.

You’ll need to make sure that you replace the various damaged threads with new threads to ensure proper fixation of the engine block.

Tools You’ll Need:

To fix the stripped bolt holes, you must know which tools you need.

These tools comply with most of the requirements for making the threads. So when you go to the hardware shop, you must know the exact torque requirements to fix your badly damaged threads.

Let’s look at the various tools you’ll need to fix the badly broken threads of your engine block.

These tools can help you recover the original condition of your engine block as they can improve the engine’s overall performance. Some tools you need to buy at the hardware shop are listed below:

How do you Fix a Broken Bolt Hole Thread?

Fixing a broken bolt hole can be a little challenging, but once you know all the tools you need, your search for a proper tool-set is over, and you need to operate.

You’ll need to follow some critical steps to avoid permanent damage. Let’s have a look at some of them:

Step 1: Increasing the Diameter of the Slipped Bolt Hole

The diameter of the stripped bolt hole needs to be increased, so you’ll need to have a drill machine with a variable tolerance limit drill bit.

Drill in the hole, and then get the proper bolt size that you need to fit in the new threads.

Step 2: Measuring the Thread Size of the Stripped Bolt Hole

The most important step is measuring the right size of the thread to be made into the drilled hole.

You can do this by the thread measurement tool that measures the thread’s pitch and the exact dimensions. After choosing the right size, get the bolt according to the female thread size.

Step 3: Inserting a Thread insert into the Bolt Hole

The next step is to insert the thread insert, which can also be referred to as a bush or a clearance ring.

You can also get this quickly or make your own according to the additional diameter size you drilled previously.

Step 4: Adding the Clearance Oil

Most of the time, the Helicoil spring fulfills most of the backlash that might exist but to prevent any other significant challenges, you need to use a clearance oil.

This oil will help uniformly distribute the new threads, which is compulsory in the case of the engine block.

Step 5: Inserting the Heli Coil Spring

Once you have inserted the thread insert, you will insert the Helicoil into the drilled hole, accommodating the new bolt.

This Helicoil spring will be the primary load restraining factor for the final fix.

You’ll need the tap and die set to insert the Helicoil spring for developing the threads.

Finally, as a precautionary measure, you need to use a magnet to attract all the metal particles out of the drilled hole and into the surrounding. You should perform this step at the end.

If the other metal dust particles fall into the bolt hole, then there might be a challenge for you to replace the screw later. The particles could again damage the new thread.

One additional point to be noted in this case is that a new thread requires a certain amount of time to accept the new clearance diameter.

Any oil leakage from the engine block can identify a sign of spam in the new thread.

Final Thoughts

So, in conclusion, all you need to do is choose the right tools to repair the stripped bolt hole.

Otherwise, it will be a significant challenge for you to maintain the performance of your engine.

Engine performance can significantly be hindered due to substantial ill effects of the stripped bolt holes, so before going in for a repair, use a torque wrench to its full use.

ABOUT THE AUTHOR

Dean Alvarez, TireForge Head Author

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