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Gudgeon / Piston Pin Failure: Possible Causes (Explained)

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Last Updated on: 7th September 2023, 12:37 am

The gudgeon pin (also known as a piston or wrist pin) plays a critical role in the engine’s function. Like any mechanical part, it can fail.

In this article, we will explore the possible causes and types of gudgeon pin failure and discuss potential preventative measures.

damaged gudgeon pin

Role of the Gudgeon Pin

The gudgeon pin is a cylindrical metal rod, it connects the piston to the connecting rod within the engine.

This pin allows the piston to pivot, transferring the force generated by the combustion process to the connecting rod.

As the piston moves up and down within the cylinder, the gudgeon pin endures high stress, heat, and friction. It’s this relentless cycle of pressure and motion that can ultimately lead to failure.

Causes of Gudgeon Pin Failure

  1. Excessive Heat: High operating temperatures due to poor cooling systems or prolonged heavy loads can cause the pin to overheat, leading to distortion, weakening, and eventually failure.
  2. Lubrication Issues: Inadequate lubrication from a low oil level, insufficient oil circulation or inadequate servicing can result in increased friction, accelerating wear and contributing to premature gudgeon pin failure.
  3. Quality of the Pin: Low quality materials used in the manufacturing of the gudgeon pin can compromise its strength and durability, making it more prone to breaking under stress.
  4. Engine Knocking: Engine knocking is where the air-fuel mixture ignites prematurely or unevenly. This can cause intense pressure spikes within the cylinder, subjecting the pin to excessive forces which can cause damage and failure.
  5. Vibration and Misalignment: Engine vibrations or misalignment of components can lead to uneven stress distribution on the gudgeon pin, causing it to weaken over time.
  6. Overspeed: If the engine revs to too high of an RPM it can also lead to damage to the piston pin.
  7. Hydraulic Locking: If the engine seizes up due to hydro-locking (such as if the engine intakes too much water) it can cause extreme stress on the piston, connecting rod and the wrist pin, leading to failure.
  8. Overloading: Overloading the gudgeon pins due to a higher power and torque output can lead to failure of the pin.
  9. Lightweight Gudgeon Pin: A pin that is lightweight for tuning purposes (to reduce weight of the moving engine parts) can also be susceptible to damage from high stress.
examples of piston pin failure

How to Prevent Piston Pin Failure

  1. Proper Lubrication: Ensuring a steady supply of clean and high-quality engine oil will help reduce friction and wear on the gudgeon pin. Regular oil changes and using the manufacturer-recommended oil type are essential.
  2. Cooling System Maintenance: A well-maintained or upgraded cooling system prevents excessive heat buildup in the engine. Regularly check coolant levels, inspect hoses and radiators, and address any issues.
  3. Quality Parts: Always use genuine OEM or high-quality replacement parts, including gudgeon pins, when servicing your engine. Cutting corners with low-quality and cheap components can lead to failures.
  4. Tuning and Timing: Proper engine tuning and timing can reduce the occurrence of engine knocking, reducing stress on the gudgeon pin and other parts.
  5. Balancing and Alignment: Ensuring that all engine components are properly balanced and aligned helps distribute forces evenly, reducing the risk of stress concentration on the gudgeon pin.


The gudgeon pin’s role within the engine is often overlooked and not thought to be a major part, but its proper functioning is crucial.

There are many causes for failure of the gudgeon pin, as listed in this article. It’s important to take these into consideration when tuning your vehicle.

What are the symptoms of gudgeon pin failure?

The symptoms of a pin failure can include unusual engine noise (rattling or knocking noises), seizing and locking of the engine, and generally running rough.

When should I upgrade my wrist pins?

If you’re using forced induction, NOS, high rpm or heavy sustained loading on your engine, upgraded wrist pins represent a great longevity modification.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer. He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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