What Are Engine Bearings and Why Are They Important?

Reviewed by

Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on January 23rd, 2025

Reading Time: 5 minutes
Summary
  • Engine bearings are the main supports for the major moving parts of an engine, reinforcing the operating loads and reducing the friction these parts generate.
  • Signs of bad engine bearings include knocking noises in the engine, overheating, metal particles in the engine oil, and low engine oil pressure levels.
  • You can take care of your vehicle’s engine bearings by lubricating them properly, getting regular maintenance, and not letting the engine overheat.

Have you ever wondered how all the different parts of the engine are capable of moving without scraping against one another? You can thank engine bearings for that. These small yet significant auto parts do the heavy lifting and ensure engines operate smoothly.

What Are Engine Bearings?

Bearings “bear” loads, thus, they’re called “bearings.” When you think of bearings you might think of bearings with balls, needles, or rollers, but engine bearings don’t have moving parts.

Engine bearings are the main supports for the major moving parts of an engine, reinforcing the operating loads and reducing the friction these parts generate. In other words, they affect the overall durability and longevity of an engine.

Diagram showing engine bearings and where they are located | Image Source: Richard McCuistian

What Are Engine Bearings Usually Made Of?

Because they’re crucial when it comes to the functionality of the engine, engine bearings need to be durable and able to withstand high loads. Because of this, they’re typically made of the following metals and alloys: babbitt, trimetal, and aluminum.

Babbitt

Babbitt is one of the most commonly used materials in engine bearing manufacturing. It’s a metal fashioned from lead, tin, and antimony. Its properties make it ideal for making soft shafts that run under moderate loads and speeds. Babbitt works with occasional borderline lubrication and oil starvation without failure.

Trimetal

Engine bearings are also made of trimetal — a copper-lead alloy that’s often made with tin. This alloy is stronger and more durable than babbitt, but it’s also more expensive. Due to its make, it’s prone to acid damage. This means it’s often overlaid with babbitt, which is resistant to corrosion.

Aluminum

Another material that’s used to make engine bearings is aluminum. These bearings are often made with aluminum alloys that contain small quantities of tin and silicone. The resulting alloy is more powerful and durable than both babbitt and trimetal, but it’s also significantly more expensive.

Aluminum bearings are best used for high-speed, high-load conditions. On top of that, they also do not contain toxic materials such as lead.

Where Can You Find the Engine Bearings?

Because engine bearings are designed to support the moving components of an engine, they can be found in many places. These locations will vary depending on the vehicle’s make and model, but you can typically expect to find the main engine bearings in the crankcase.

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: The connecting rod bearings are at the base of the rod where it connects to the crankshaft. The camshaft doesn’t usually have bearings on overhead cam engines but does have circular bearings on cam-in-block engines.

Bad Engine Bearing Signs

The most common signs your engine bearings are starting to fail include strange noises coming from the engine, an overheating engine, the presence of metal particles in the engine oil, and low engine oil pressure.

Unusual Engine Noises

This 2007 Cobalt hit something in the road and breached the oil pan and was driven until all the oil was gone and this happened. This engine seized up. | Image Source: Richard McCuistian

If you hear strange knocking noises coming from the engine, there’s a chance the bearings are damaged and due for replacement. When the bearings get worn enough from oil starvation or general engine wear, you’ll hear knocking.

Watch these videos to hear examples of engine knock:

Overheating Engine

When moving parts in the engine rub against one another, they generate friction. Engine oil is pumped to the bearings to minimize friction. The oil prevents metal-to-metal contact.

Metal Particles in Engine Oil

When bearings wear down from overuse, bits of metal break away from it. These bits can potentially mix with the engine oil, potentially causing serious damage to the engine if the problem isn’t addressed.

You can send a sample of your engine oil to a laboratory for analysis (Blackstone is one lab that does this). You can buy a kit and send them the oil and they will send you a report.

Low Engine Oil Pressure

The more damaged an engine bearing is, the more likely it is for engine oil to leak out. This reduces the overall levels of pressure in the oil.

Taking Care of Your Engine Bearings

To ensure your engine bearings last as long as possible, get regular oil changes.

Getting Regular Maintenance

Engine oil should be changed every 5000 miles unless you’re using full synthetic oil and the OEM manual calls for longer intervals.

Maintenance is one of the most important things a driver needs to do. It’s best to bring your vehicle to an auto shop for maintenance at least once every six months.

Frequently Asked Questions

Here are some commonly asked questions about engine bearings.

How much is the engine bearing replacement cost?

The cost of replacing your engine bearings will vary depending on the make and model of your vehicle. The number bearings that need to be replaced can also affect the replacement cost. You can expect to spend approximately $5000 to $11,000 including labor costs.

How long do engine bearings usually last?

Engine bearings last the life of the car, unless the engine isn’t maintained properly.

What are the different engine bearing sizes?

Engine bearings are available in standard size; however, they also come in undersize. In undersize, they are available in measurements 0.010, 0.020, and 0.030.

Get OE-Grade Engine Main Bearings Online

Engine bearings or the engine main bearings are one of the critical components of an engine. In the unlikely event that they wear out, you’ll need to replace them. Otherwise, you risk damaging other components. If ignored, bad bearings can cause the engine to overheat and get damaged. If you need to replace your bearings, do so immediately.

Good thing CarParts.com makes it easy to get the parts you need, thanks to our easy-to-use website and fast shipping. Aside from engine bearings, CarParts.com is also a one-stop shop for a wide range of engine components including pistons, spark plugs, and camshafts, to name a few.

We source our parts from only the best manufacturers in the industry to guarantee their quality. Our strategically located warehouses also mean we can ship your order to your doorstep in as fast as two business days.

Get your engine’s performance back as soon as possible. Check out our selection of engine main bearings and order from CarParts.com today!

Reviewed By Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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Published by
CarParts.com Research Team and Richard McCuistian, ASE Certified Master Automobile Technician
Tags: main-bearing