Maintenance Tips, Tricks And Hacks For Your Vehicle

Engine Bearing Failure Symptoms: Causes, Prevention, and Fixes




Engine bearings are integral components of any vehicle, ensuring the smooth operation of moving parts within the engine.

However, when these essential elements begin to fail, they can manifest a host of symptoms that can impact your vehicle’s performance and safety.

Key Takeaway

  • Engine bearings are specialized types of bearings that provide a frictionless surface between the moving parts of an engine, reducing wear and tear and aiding in heat dissipation.
  • Symptoms of engine bearing failure can include unusual noise in the engine, decreased oil pressure, engine overheating, rough idles, knocking engine sound, and the presence of metal shavings in the oil.
  • Engine bearing failure is primarily caused by lack of or improper lubrication, presence of dirt and debris, and running the bearing at a load above its fatigue limit, all leading to increased friction and premature wear.

What Are Engine Bearings

Engine bearings are crucial components in a vehicle’s engine that support mechanical elements and facilitate their movement relative to other parts with minimal power loss.

These bearings significantly reduce friction between moving parts of machine elements, allowing movement in a desired direction with minimal resistance.

They play vital roles such as supporting moving parts like crankshafts and connecting rods. In a piston engine, the main bearings hold the crankshaft in place and allow it to rotate within the engine block.

Engine bearings also protect rotating shafts like camshafts and crankshafts by supporting a layer of lubrication.

These bearings are one of the most important parts of an engine and require the utmost precision during production.

High-quality engine bearings can significantly enhance the performance and lifespan of an engine.

Symptoms of Engine Bearing Failure

Engine Bearing Failure Symptoms Causes, Prevention, and Fixes

Symptoms of engine bearing failure include:

1. Noise in the Engine

One of the most common symptoms of engine bearing failure is noise emanating from the engine. Drivers may be familiar with the term ‘rod knock’, a type of noise that indicates a worn-out bearing. The noise is usually a result of the bearing no longer providing a smooth surface for the engine parts to move against, causing them to knock against each other.

2. Low Oil Pressure

Decreased oil pressure can be a sign of a failing engine bearing. When bearings start to wear out or fail, they may allow oil to leak out, which can lead to a reduction in the overall oil pressure in the engine. Low oil pressure often indicates that the bearing is not functioning as it should.

3. Engine Overheating

Overheating can be another symptom of engine bearing failure. When the bearings fail to provide a smooth surface for the moving parts of the engine, it can cause excessive friction, leading to increased heat production. If left unchecked, this can result in the engine overheating.

4. Knocking Engine Sound

A knocking sound in the engine, also known as a rod knock, is a major symptom of engine bearing failure. This knocking sound is indicative of the bearing being worn out and unable to effectively reduce the friction between the moving parts of the engine.

5. Metal Shavings in Oil

The presence of metal shavings in your engine oil can be a clear sign of a bad crankshaft bearing. As the bearing wears down, it can release small pieces of metal into the oil, which can be detected upon inspection. This symptom requires immediate attention as it could lead to serious engine damage if left untreated.

What Causes Engine Bearing Failure

Engine bearing failure can be attributed to a variety of factors, all of which can have a detrimental impact on your engine’s performance and lifespan. Here are some of the most common causes:

1. Insufficient Lubrication

The primary cause of engine bearing failure is insufficient lubrication. Bearings rely heavily on oil to reduce friction between moving parts. If there is not enough oil, or if the oil is dirty and can’t effectively lubricate the bearings, they can wear out prematurely.

2. Overloading

Overloading can also lead to engine bearing failure. This occurs when the engine is made to carry more weight than it was designed for, leading to excessive pressure on the bearings. Over time, this increased load can cause the bearings to fail.

3. Dirt and Contaminants

Dirt and other contaminants in the engine can cause significant damage to the bearings. These particles can get into the oil and scratch the surface of the bearings, leading to their eventual failure.

4. Misalignment

Misalignment of the bearings can lead to uneven wear and tear, resulting in their premature failure. This usually happens when the engine components are not installed correctly.

5. Normal Wear and Tear

Finally, normal wear and tear is a common cause of engine bearing failure. Over time, the constant friction between the bearings and the engine parts can cause the bearings to wear out and eventually fail. Regular maintenance and timely replacement can help to prevent this.

How To Diagnose a Failing Engine Bearings

Diagnosing a failing engine bearing is crucial to prevent severe damage to your engine. Follow these steps to accurately determine if your engine bearings are failing:

1. Listen for Unusual Noises

The first step in diagnosing a failing engine bearing is to listen for unusual noises. A knocking or rumbling sound coming from your engine, particularly when accelerating, is often a sign of a bad bearing.

2. Check the Oil Pressure

Next, check your oil pressure. If the oil pressure is lower than usual, it could be a sign that your engine bearings are failing. Most cars have an oil pressure gauge or light that will alert you to low oil pressure.

3. Look for Metal Shavings in the Oil

Metal shavings in the oil is a clear sign of a problem with your engine bearings. You can check this by draining a small amount of oil from the engine and examining it for metal particles.

4. Inspect for Overheating

Overheating can also be a sign of failing engine bearings. If your engine is overheating, it could be due to excess friction caused by worn-out bearings. Check your temperature gauge regularly to ensure your engine isn’t overheating.

5. Seek Professional Help

If you’ve noticed any of the above symptoms, it’s best to seek professional help. A mechanic has the tools and knowledge to accurately diagnose engine bearing failure. They can confirm your suspicions and advise on the necessary repairs or replacements.

How To Fix Failed Engine Bearings

Fixing failed engine bearings requires a meticulous process that involves a deep understanding of your vehicle’s engine. Here’s a step-by-step guide on how to address this issue:

1. Identify the Problem

Firstly, confirm that the problem is indeed with the engine bearings. As discussed above, common symptoms include unusual noises from the engine, lower oil pressure, metal shavings in the oil, and overheating. If you’ve noticed any of these signs, it’s highly likely that your engine bearings need attention.

2. Prepare the Necessary Tools and Parts

You’ll need the correct tools and replacement parts to carry out this task. This includes a new set of engine bearings and the necessary tools to dismantle and reassemble your engine. Remember, selecting the right engine-bearing material is crucial as this can prevent future failures.

3. Dismantle the Engine

With your tools and parts ready, proceed to carefully dismantle the engine. Be sure to keep track of all components and their placements. This step needs to be done meticulously to avoid causing further damage to the engine.

4. Replace the Faulty Bearings

Once the engine is dismantled, locate and replace the faulty bearings. Be sure to check other parts for wear and tear as well, especially the thrust bearings.

5. Reassemble the Engine

After replacing the faulty bearings, reassemble the engine. Make sure that all parts are correctly aligned to prevent misassembly, which could lead to more problems down the line.

6. Test the Engine

Once the engine is back together, conduct a test run to ensure everything is working correctly. Listen for any unusual sounds and check for any signs of overheating or low oil pressure.

While it’s possible to replace engine bearings yourself, it’s important to note that this is not a common repair and requires a certain level of expertise. If you’re unsure or uncomfortable performing this task, it’s best to seek professional help.

How To Prevent Early Engine Bearing Failure

Preventing early engine bearing failure involves a series of steps that focus on proper maintenance, lubrication, and installation practices.

  • Use the proper grease when lubricating the bearings. Using the incorrect type can lead to lubrication failure.
  • Ensure good-quality multi-viscosity engine oils are used to prevent bearings from being starved for lubrication.
  • Avoid mixed lubrication with direct metal-to-metal contact between the bearing and crankshaft.
  • Follow best practices for mounting and installing bearings to prevent premature failure.
  • Regularly check for misalignment, unbalance, and looseness as these issues can lead to bearing damage.
  • Extend the life of your bearings by following a consistent maintenance schedule.

How Much Does It Cost To Fix Engine Bearings?

On average, you can expect to pay between $2,000 and $3,000 for the replacement of engine bearings. This price usually includes both parts and labor.

It’s important to note that the bearings themselves don’t typically cost more than $250, but the labor can significantly add to the overall expense, potentially costing anywhere between $1,000 to $2,000.

Can You Drive a Car With Bad Bearings?

Driving a car with bad bearings can lead to severe engine damage and potentially dangerous situations on the road due to the risk of complete engine failure.

While it is technically possible to drive a car with bad bearings, it’s highly inadvisable. The bearings in your engine play a crucial role in ensuring the smooth operation of moving parts.

If they’re damaged or worn out, they can cause serious damage to your engine, leading to more expensive repairs down the line.

Furthermore, driving with bad bearings can be dangerous as it could lead to complete engine failure while you’re on the road.

What Happens When Engine Bearings Fail?

Engine bearings play a crucial role in the operation of an engine, and their failure can lead to several issues:

  • Increased Friction: Bearings reduce friction between moving parts in the engine. When they fail, friction increases, which can lead to overheating and severe damage to engine components.
  • Abnormal Noises: A common symptom of bearing failure is abnormal noise from the engine, such as a knocking or rumbling sound. These noises are often louder when the engine is under load.
  • Oil Pressure Problems: Failed bearings can cause low oil pressure, which can further damage other engine components and potentially lead to engine failure.
  • Engine Seizure: In extreme cases, failed bearings can cause the engine to seize up completely. This happens when the bearings are so worn or damaged that they can no longer support the movement of the engine’s components.
  • Potential Breakdown: Ultimately, driving with failed engine bearings can lead to a complete vehicle breakdown, leaving you stranded and facing costly repairs.

What Does a Failing Engine Bearing Sound Like?

A failing engine bearing often produces a distinct noise that’s typically described as a low rumble, knocking, or thumping sound.

This noise usually changes as you accelerate and decelerate, becoming louder as the bearing wears more.

In some cases, this sound has been referred to as ‘rod knock’, which is a significant symptom of bad engine bearings.

Furthermore, as the bearings wear, the play between the crank and the connecting rod increases, resulting in a banging sound.

Do Bearings Usually Give Warning Before They Fail?

Yes, bearings usually give warning before they fail such as abnormal noises, such as a rumbling or knocking sound that becomes louder as the bearing deteriorates.

Increased friction due to bearing wear can cause overheating of the engine, and failed bearings can also lead to oil pressure problems.

What Is The First Indicator That Bearing is Wearing Out?

The first indicator that a bearing is wearing out often comes in the form of unusual noises. These can range from a high-pitched squealing or whining sound to a low rumbling or growling noise.

This is caused by increased friction as the smooth surface of the bearing wears away, leading to more metal-to-metal contact.

These noises may become louder or more frequent with vehicle speed or load.

It’s important to pay attention to these sounds as they are often the first sign of a problem, and early detection can prevent further damage to the engine or other vehicle components.

How Do You Detect Early Bearing Failure?

Early bearing failure can be detected by observing the following signs:

  • Unusual Noises: Bearings often produce a high-pitched squealing or a low-rumbling noise when they start to wear out. These noises may become louder or more frequent with vehicle speed or load.
  • Vibration: As bearings wear out, they can cause parts of your vehicle to vibrate. This is often felt through the steering wheel or the seat of the car.
  • Poor Vehicle Handling: Worn bearings can affect the smoothness of your ride and make your vehicle handle poorly.
  • Decreased Fuel Efficiency: If your vehicle’s fuel efficiency suddenly decreases, it could be a sign of a problem with the bearings.
  • Excessive Heat: Bearings that are failing can generate excessive heat, which can sometimes be felt near the wheel hub or seen as overheating in the engine.
  • Visual Inspection: In some cases, you might see physical damage or excessive wear when you inspect the bearing. This could include discoloration, scoring, or pitting on the surface of the bearing.
  • Oil Analysis: Metal particles in the oil can indicate bearing wear. Regular oil analysis can help detect this early sign of bearing failure.


Q: How can low oil pressure cause engine bearing failure?

A: Low oil pressure can cause engine bearing failure because the bearings rely on a continuous supply of oil for lubrication. Without sufficient oil pressure, the bearings can experience metal-to-metal contact, which can lead to damage and failure.

Q: What are the signs of low oil pressure?

A: Signs of low oil pressure include the oil pressure warning light coming on, knocking or ticking noises from the engine, loss of power, and high engine temperatures.

Q: How do engine bearings fail?

A: Engine bearings can fail due to a variety of reasons, such as wearing out over time, excessive heat, inadequate lubrication, contamination by dirt or debris, or the use of incorrect bearings.

Q: What are the main bearings and rod bearings?

A: Main bearings and rod bearings are types of bearings used in internal combustion engines. The main bearings support the crankshaft, while the rod bearings connect the connecting rods to the crankshaft.

Q: Can engine bearings be damaged by overheating?

A: Yes, engine bearings can be damaged by overheating. Excessive heat can cause the bearings to expand, lose their lubricating properties, and eventually seize, leading to failure.

Q: When should engine bearings be checked or replaced?

A: Engine bearings should be checked or replaced if you notice symptoms such as low oil pressure, knocking noises from the engine, excessive oil consumption, or metal shavings in the oil. It is also recommended to inspect the bearings during engine rebuilds or major repairs.

In Conclusion

Engine bearing failure is often signaled by several symptoms that can alert a vehicle owner to potential problems.

One of the most common signs is unusual noise, such as a loud hammering or knocking sound in the engine, which can become more pronounced with increased vehicle speed or load.

This noise is caused by the increased friction from bearings wearing out, leading to more metal-to-metal contact.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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