Engine Bearing Failure Symptoms: Causes and Prevention

The engine bearing provides support to moving parts of the engine. When this support is lost, these moving parts lose balance and cause problems like parts misaligning, internal collision, and increased friction.

When the bearing is damaged, the first sign that you may notice is the increased engine noise. It is usually a knocking sound and signifies that the engine parts collide due to the loss of support from the engine bearing.

Also another symptom is a significant reduction in the oil pressure due to the clearance created by the damaged bearing. The loss of oil pressure will also cause increased friction in the engine parts leading to engine overheating.

Here, we will look at the symptoms of a damaged engine bearing, how to diagnose a damaged bearing, and the causes of the failed bearing, along with ways to prevent damaged bearings and the cost of repairing the damage.

what causes engine bearing failure

What are the Symptoms of Engine bearing failure?

When the engine bearing fails, it comes with some signs that are difficult to ignore. These signs may include loud knocking sounds, engine overheating, loss of oil pressure, and more.

Below are bad engine bearing failure symptoms.

1. Engine overheating

A damaged engine bearing will result in excess friction, which will cause the engine to generate so much heat. As we know, the bearing helps maintain the oil pressure and prevents metal-to-metal contact.

When the bearing is damaged, the oil pressure drops gradually depending on the damage done to it. As the oil pressure reduces, friction in the moving part increases. As time goes on, your vehicle will experience engine overheating.

2. Loss of oil pressure

The engine bearing experiences wear, which could affect the oil pressure in the engine. When the bearing is worn out, the clearance between the bearing and the journal becomes more significant. It allows larger amount of oil to flow, drastically reducing the oil pressure.

As the clearance becomes more significant due to bearing wear, the engine noise will also increase.

Issues like this are more associated with vehicles with higher mileage. It means the bearing is more prone to wear out due to excessive usage.

3. Rough idles

When the engine bearings are worn out, they can no longer support the moving part, leading to the engine rocking or vibrations. Once the parts of the engine rock or vibrate without control, it causes the engine to rough idle.

4. Knocking engine sound

A major symptom of a bad engine bearing is the rod knock symptom, which is a loud hammering sound in the engine. It gets even more significant when the engine increases in RPM.

The knocking sound coming from the engine results from the worn-out bearing, which has created excess clearances. The rod’s end collides against the crankshaft at the top and bottom piston stroke. The collision will happen continuously, and as the engine engine increases in RPM, so will the knocking sound.

5. Excessive vibration

The engine bearings are a part of the engine that supports its moving parts, like the crankshaft and connecting rods. It also prevents metal-to-metal contact, which could cause quick wear.

Once the engine bearing is damaged, the moving components will bounce around during engine operation because of the loss of support. It is very dangerous to drive in such conditions as the engine parts will fail due to the excessive vibration.

How do you diagnose engine bearings?

There are two efficient ways to diagnose a bad engine bearing: paying attention to the engine for the signs of a bad bearing and physically inspecting the bearing.

A bad bearing comes with many obvious signs, which we have mentioned above. One major sign you should watch out for is the knocking sound in the engine. It is especially significant when driving; the knocking sound increases as you accelerate.

The knocking sound will also come with a check engine light, signifying something is wrong with the engine.

In addition, you will notice that the oil pressure will drop significantly. Even when you top up the oil, you will see that the oil pressure will go down faster than usual.

If you are unsatisfied with the symptoms, you can go ahead and find the bearing. The main bearings are mounted between the crankcase and the engine block. 

To check the engine bearing, you may need professional help or at least have a little mechanical knowledge. It ensures no further damage to the bearing or other engine parts.

engine bearing failure analysis guide

What Causes Engine Bearing Failure Earlier

There are a lot of factors that could cause the bearing to fail. However, improper oil is a leading cause. Other causes may include contamination, misalignment between the crankshaft and bearing body, etc.

Below are what causes engine bearings to go bad.

Improper lubrication

A major cause of engine bearing failure is the wrong oil type or low engine oil. When this happens, the engine bearing will not receive the right amount of lubrication, causing excessive friction in the part.

Friction in the engine part could cause the bearing to wear faster than expected.


A misalignment in the crankshaft and bearing housing could also cause the engine bearing to get damaged. Issues with the crankshaft, including bent parts or improperly positioned crankshafts, could cause unnecessary vibration in the engine.

Any excessive vibration in the crankshaft could harm other engine parts, including the engine bearing. It would cause it to grind against other components, causing an increase in wear.

Corrosion and contamination

Water, sand or any other contamination that finds its way to the bearing can cause serious damage to its assemblies. It can contaminate the oil in the bearing, reducing its lubricative power. When this happens, the engine bearing will experience excessive wear and may fail.


Spalling or fatigue refers to fractures in the bearing surfaces, which could lead to the breaking off of the bearing parts. As the spalling spreads, eventually, the engine bearing will fail.

Engine overheating

Due to issues with the cooling system or low oil pressure in the engine, the engine would overheat, leading to serious problems for the bearing assembly. Due to the extreme heat, the bearing surface could get cracked, which will expand as time goes on. If not checked and fixed, the bearing will fail in such conditions.  

How do you prevent early Engine bearing failure?

Below are ways to prevent your vehicle from having an engine-bearing failure or exhibiting engine-bearing symptoms.

  • Always check the vehicle manual for the recommended engine oil and ensure you use the recommended one or a similar type.
  • Always take your vehicle for servicing at the right time frame.
  • When replacing the engine bearing, choose the right bearing design.
  • Ensure that the bearing is installed properly.
  • Ensure the seals for the hardening wear are in good condition.
  • Periodically check the engine oil to ensure it is in good condition and not below the recommended level.

How much does it cost to fix engine bearings?

According to motorverso.com, it will cost $2,000 to $3,000 to have the bearing replaced and in good condition. The cost includes the spare parts and the cost of labor.

The price of fixing the engine bearing depends on many factors. One factor is the type of vehicle the repair is being done on. If it is a luxurious vehicle, having the bearing replaced will cost a lot more.

Also, another factor that could affect the price of the bearing repair is your location and the mechanic you will be using. Some mechanics may charge more than others, depending on factors known to them.

Finally, other damages that the faulty bearing may have caused could contribute to the cost of repairing the bearing.

Can I drive my car with bad bearings?

Avoid driving a vehicle with a bad bearing, as it is unsafe and can further damage the engine parts, leading to engine failure. The more the damages caused by the faulty engine bearing, the more the repair cost.

The bearing is a core part of the engine that supports moving parts of the vehicle, like the crankshaft. Once the bearing is damaged, the engine parts will have excessive movement and vibration, which could cause serious damage if not checked.

Also, a damaged bearing allows contaminations to get to the oil in the engine. When the bearing is damaged, spaces are created for dirt or water to get to the oiling system and circulate through the crankcase, causing damage to the camshaft and the lifters.

The contamination could also get to the cylinders, where it accumulates, scores piston skirts, and damages other parts. As this goes on, eventually, the engine will fail.

Final Words

Issues with the engine bearing should not be ignored but treated with urgency. A bearing failure can lead to major problems with the engine, which could be costly to repair if not checked early enough. It would help if you did all you could to prevent a bearing failure by having a good maintenance culture for your engine. You could consider several factors that could prevent engine failure, like proper lubrication, using high-quality bearings, and more.

Akindayini Temiloluwa

I am passionate about everything automotive. Right from when I got my first toy car as a kid, I developed an interest in the inner workings of vehicles. As I grew up, my love for mechanical stuff became more substantial enough for me to pursue a career in it. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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