Hole in Transmission Bell Housing: What to Do? Quick and Friendly Solutions

A hole in the transmission bell housing can be a major concern for vehicle owners.

This important component serves as the protective enclosure for your vehicle’s transmission and clutch, ensuring that they operate smoothly and efficiently.

When damage occurs to the bell housing, such as a hole, it’s crucial to address the issue promptly and correctly.

It’s important to understand the underlying causes of bell housing damage and have a basic knowledge of the bell housing system itself.

Once you’ve identified and understood the issue with your transmission bell housing, it’s time to explore repair options and procedures.

In this article, we will cover all of these points in details.

Hole in Transmission Bell Housing

Key Takeaways

  • Identify and understand the cause of the hole in your transmission bell housing.
  • Familiarize yourself with the bell housing system and the measurement process for accurate damage assessment.
  • Explore repair options and seek professional assistance if needed to ensure proper repair and vehicle performance.

Recognizing Transmission Bell Housing Damage

Signs of Engine Misalignment

  • Vibration or shaking: If you notice unusual vibrations or shaking while driving, this could indicate engine misalignment issues.

  • Odd noises: Listen for any abnormal sounds, such as clunking or grinding. These noises may emerge due to misaligned transmission bellhousing components.

Identifying Hole in Bell Housing

  1. Visual inspection: Examine the exterior of the bellhousing carefully. Look for cracks, holes, or visible damage that could compromise its integrity.

  2. Transmission fluid leaks: Keep an eye out for leaking transmission fluid, which may appear as puddles under your vehicle. An accumulation of dirt around the leak area could also indicate a hole in the bellhousing.

Recognizing Crank Centerline Issues

  • Bearing wear: When the crank centerline is misaligned, it can lead to excessive bearing wear and eventual engine failure. Inspect the bearings for signs of wear.

  • Input shaft damage: A misaligned bellhousing can cause stress on the transmission’s input shaft, leading to damage and potential failure. Make sure to examine the input shaft for visible wear or damage.

By paying close attention to these signs and performing regular maintenance, you can avoid major transmission problems and keep your vehicle running smoothly.

Causes of Bell Housing Damage

Excessive Torque Stress

Excessive torque can cause damage to your bell housing.

When the engine produces too much torque, it may put pressure on the clutch and flywheel, leading to failure.

To prevent this, ensure your engine is well-maintained and within its recommended torque range.

Mechanical Failure

Mechanical failure in components like the clutch and flywheel can lead to bell housing damage.

A worn-out clutch, for example, can crack the bell housing or misalign its position.

Regular inspections and routine maintenance can help prevent such mechanical failures.

Core Shift Issues

Core shift refers to irregularities in the casting of the bell housing.

If there is a core shift issue, it could result in imbalanced forces and possible failure.

To address this, select high-quality bell housings with strict manufacturing standards.

Wear and Tear Effects

Naturally, wear and tear will affect your bell housing over time.

Constant exposure to friction, heat, and pressure could eventually cause a hole in the transmission bell housing.

Regular inspections and timely repairs can minimize the effects of wear and tear on the component.

Understanding the Bell Housing System

Role of Clutch and Flywheel

The bell housing encloses essential components such as the clutch and flywheel.

The clutch assists in the transfer of power from the engine to the transmission by linking the engine to the gearbox.

As for the flywheel, it helps balance the engine and acts as an energy storage device during gear shifts.

Significance of Alignment Pins

Proper alignment of the bell housing is crucial for the efficient functioning of the transmission.

Alignment pins are key in ensuring correct positioning. They secure the bell housing to the back of the engine, keeping the crankshaft and input shaft aligned, and preventing premature wear.

Functionality of Starter Motor

Lastly, the starter motor operates within the bell housing system, connecting to the flywheel.

When you turn the ignition key, the starter motor initiates the engine by rotating the flywheel, which causes the crankshaft to spin and the engine to begin operation.

The Measurement Process

Usage of Dial Indicator

Dial indicator is a precise measuring tool used in checking bell housing alignment.

To use a dial indicator, set it up with the pin just touching the inside diameter of the bell housing’s transmission front bearing retainer opening.

Zero the dial indicator and turn the flywheel/crank slowly for 360 degrees while watching the needle closely. The needle movement should be 0.010-inch or under1.

Importance of Inside Diameter

Monitoring the inside diameter of the transmission bell housing plays a crucial role in ensuring proper alignment.

If the inside diameter is not uniform or balanced, it can lead to off-center conditions which require the use of offset dowel pins to correct the alignment2.

This is essential for proper clutch function and preventing unnecessary power loss.

Purpose of Magnetic Base

A magnetic base is used to securely attach the dial indicator to the engine block or bell housing during the measurement process.

This ensures accuracy in readings and helps maintain the dial indicator’s stability.

A strong magnetic base is ideal for properly aligning the transmission input shaft centerline and engine crankshaft centerline3.

How To Repair a Hole in Transmission Bell Housing

Implementing Weld-On Dowel Pin Kit

A weld-on dowel pin kit can be useful for repairing a small crack or hole in the transmission bell housing.

This process involves welding a dowel pin onto the damaged area to reinforce the structure. Ensure that you:

  • Thoroughly clean the area around the hole before starting the repair.
  • Utilize proper welding techniques to avoid further damage.

Here is a step by step guide.

1. Safety First:

  • Always wear safety glasses, welding gloves, and protective clothing.
  • Ensure the workspace is well-ventilated.
  • Disconnect the battery before starting any welding work.

2. Prepare the Transmission:

  • Remove the transmission from the vehicle.
  • Clean the area around the damaged hole to remove any dirt, grease, or oil. This will ensure a clean welding surface.

3. Inspect the Damage:

  • Examine the damaged hole to determine the extent of the damage.
  • If the hole is only slightly enlarged, you may be able to weld it shut and then re-drill it to the correct size.

4. Use the Weld-On Dowel Pin Kit:

  • The kit typically includes a dowel pin and a sleeve.
  • Insert the sleeve into the damaged hole. The sleeve acts as a guide for the new dowel pin and provides additional material for welding.
  • Position the dowel pin into the sleeve.

5. Welding:

  • Using a MIG or TIG welder, weld the sleeve and dowel pin in place. Ensure you achieve good penetration for a strong weld.
  • Weld around the entire circumference of the sleeve to ensure it’s securely attached to the bell housing.

6. Finishing:

  • After welding, allow the area to cool.
  • Use a grinder or file to smooth out any weld spatter or rough edges.
  • If necessary, re-drill the hole to the correct size using a drill and the appropriate-sized bit.

7. Reinstall the Transmission:

  • Once the repair is complete, reinstall the transmission onto the engine block, ensuring proper alignment using the newly installed dowel pin.
  • Reconnect any components that were disconnected during the removal process.

8. Test:

  • Reconnect the battery.
  • Start the vehicle and check the operation of the transmission. Ensure there are no unusual noises or vibrations.

Replacing Bearings

When dealing with a damaged bell housing, it’s also essential to check your transmission’s bearings for any signs of wear or damage.

If you find any issues, consider replacing them to improve your vehicle’s performance. Remember to:

  • Fully inspect the bearings for potential wear or damage.
  • Replace any faulty bearings with high-quality, compatible parts.

Honing Procedures

Honing the transmission is recommended to smooth out any imperfections caused by the damage.

This process involves using a honing tool to remove any irregularities and to create a clean surface. 

Typically honing should be doned by a trained technical person, and is not a DIY task.

Repair MethodProsCons
Weld-on Dowel Pin Kit– Quick solution
– Affordable
– Not suitable for larger holes
– Welding skills required
Replacing Bearings– Potential performance improvement
– Relatively simple process
– May require additional disassembly
– Necessary only if bearings are damaged
Honing Procedures– Smooth surface restoration
– Can prevent further damage
– Requires specialized tools
– Not always necessary for smaller repairs

Keep these repair options in mind as you assess the damage to your transmission bell housing, allowing you to choose the most effective solution for your specific situation.


The transmission bell housing is a vital component that protects and ensures the efficient operation of your vehicle’s transmission and clutch.

Damage to this component, especially in the form of holes, can compromise the performance and safety of your vehicle.

Understanding the root causes of such damage, the intricacies of the bell housing system, and the appropriate repair procedures is paramount.

Whether you opt for a weld-on dowel pin kit, replace bearings, or undertake honing procedures, it’s essential to approach the repair with precision and care.

While some solutions can be managed by experienced DIY enthusiasts, others might require professional intervention.

Regular inspections and maintenance can help prevent such issues, ensuring your vehicle’s longevity and optimal performance.

Frequently Asked Questions

Can I use an automatic transmission with a cracked bell housing?

It is not advisable to use an automatic transmission with a cracked bell housing. A cracked bell housing can cause issues with proper alignment, inadequate torque transfer, and might even lead to mechanical failures. It is best to address the issue immediately by repairing or replacing the bell housing.

How do I repair a hole in my Nissan’s transmission bell housing?

To repair a hole in a Nissan’s transmission bell housing, clean the area surrounding the hole and apply a suitable adhesive like Permatex clear RTV silicone adhesive. Attach a sheet metal patch over the hole, secure it with duct tape, and let it set for 12 hours. Be cautious when drilling holes to avoid further damage.

What are the consequences of driving with a cracked bell housing?

Driving with a cracked bell housing can lead to:

  • Misalignment of the transmission and engine, causing excessive wear on internal components
  • Leaking transmission fluid, potentially damaging the transmission
  • Increased risk of catastrophic failure, resulting in expensive repairs or replacements

Is there a way to cover a hole in a Chevy Silverado’s transmission bell housing?

Yes, you can cover a hole in a Chevy Silverado’s transmission bell housing by cleaning the area around the hole, applying a suitable adhesive like Permatex clear RTV silicone adhesive, and attaching a sheet metal patch. Secure the patch with duct tape and let it cure for 12 hours.

Can you fix a cracked transmission bell housing on a Chevy?

While it is possible to repair a cracked transmission bell housing on a Chevy using adhesive and a sheet metal patch, it is recommended to consult with a professional mechanic. In some cases, replacement may be the best option to ensure the long-term integrity of your transmission.

What causes a hole in transmission bell housing and how to prevent it?

Common causes of a hole in transmission bell housing:

  • Physical impact from road debris or obstacles
  • Stress fractures from normal wear and tear
  • Manufacturing defects or poor-quality materials

To prevent a hole in transmission bell housing:

  • Regularly inspect the bell housing for signs of wear or damage
  • Ensure proper alignment of your engine and transmission
  • Drive cautiously to avoid impacts that may lead to damage
  • Seek professional assistance for diagnosis and repair if you suspect an issue


  1. Modern Driveline, “HOW TO: Properly Align & Index your Bellhousing.” https://moderndriveline.com/how-to-properly-align-index-your-bellhousing.

  2. Circle Track Magazine, “Bellhousing Alignment – Preventing Unnecessary Power Loss.” https://www.circletrack.com/tech-qa/ctrp-0806-bellhousing-alignment.

  3. OnAllCylinders, “3 Steps to Proper Bellhousing Alignment & Offset Dowel.” https://www.onallcylinders.com/2012/06/19/3-steps-to-proper-bellhousing-alignment-offset-dowel.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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