Best BMW 3 series engine in 5 generations

Best BMW 3 series engine

Let’s look at the most reliable BMW 3 series engine from the last five generations. Our subjects being the BMW E21, E36, E46, E90, and F30.

BMW 3 series reliability is a hot topic among fans and lovers.  That is with good enough reasons because this is potentially the best-selling BMW series, which brings both love and contempt from some corners.

In reality, some 3-series engines are lemons, but some are jewels. With that in mind, let’s find out which BMW 3 Series engine is the finest.



1st Gen. BMW 3 series engines - E21 Era

Best BMW 3 series engine - E21 Era

There were two gasoline engines that powered the first-generation BMW 3 series. They are the straight 4 – M10 and the straight 6 – M20.

Best BMW 3 series engine - M10

The BMW M10 was produced from 1962 through 1988. BMW engineers were inspired by their success with the Formula 2 racing engine, the M115. 

The lightweight aluminum design and monumental valve train technology in the M10 engine were inspired by its racing version.

With a cast iron block, an aluminum alloy head, and two valves per cylinder, the build quality was excellent. The M10 had a chain-driven camshaft, as well as a single overhead camshaft motor. 

The BMW M10 engine had displacement options ranging from 1.5 to 2.0 liters, depending on the type, and was powered by a mechanical fuel injection system.

BMW M10 engine reliability

Despite the superb build quality, this engine had a few issues, such as the timing chain tensioner failing—oil leaks from a variety of sources, including gaskets and valve covers.

The M10 carburetor issues from early three-series BMWs also left customers with a bad experience owing to fuel leaks, clogged jets, or improper fuel mixture.

Needless to say, you’re better off without this engine. That project car from this period sitting in a backyard somewhere could have stalled due to the reasons stated above.

BMWs using the M10 engine

The BMW M10 engine was used in several vehicles, including the BMW 1500, BMW 2002, BMW E21 3 Series, and the iconic BMW 2002 Turbo.

Best BMW 3 series engine - M20

Best BMW 3 series engine


The BMW M20 engine is a six-cylinder inline engine that was launched in the early 1980s. It advanced in technology and performance over the previous M10 engine. 

BMW’s brilliant inline 6-cylinder design could have begun with this powerplant. 

Throughout its production run, the BMW M20 engine came in a variety of displacements. It had a displacement of 2.0 liters (1990 cc) at inception, which was later increased to 2.5 liters (2494 cc) and 2.7 liters (2693 cc) in later variants. 

The M20 engine had a six-cylinder inline configuration, with each cylinder displacing around 333 cc.

The BMW M20 engine’s fuel delivery systems were improved throughout its manufacturing. 

Carburetors were used in early versions, but fuel injection systems were eventually installed to improve performance and fuel efficiency. The use of fuel injection technology increased the power output and responsiveness of the M20 engine.

Furthermore, the BMW M20 engine served as the foundation for several high-performance variations created by BMW’s motorsport division, including the famous M20B25 engine in the classic BMW E30 M3. 

These high-performance engines included revisions to the cylinder heads, new camshafts, and better intake and exhaust systems, resulting in even greater power and performance.

Was this engine any better than its predecessor?

Continue reading to find out…

BMW M20 Engine Reliability

A few concerns arose, the most serious of which were cooling issues characterized by coolant leaks, radiator failures, and thermostat malfunctions.

The BMW M20 engine timing belt and timing chain were both reported to be weak points, with repeated breakdowns.

The issues with this engine were compounded by the recently developed fuel injection system. The problems included clogged injectors and malfunctioning fuel pumps.

To summarize, this is an engine you should avoid unless you have the requisite technical abilities to correct the flaws described, as well as a budget to sustain the repairs.

BMWs using the M20 engine

The BMW E30 3- Series, available as a coupe, sedan, and convertible ran on the M20 engine.

2nd Gen. BMW 3 series engines - E36 Era

Best BMW 3 series engine - E36 Era

Best BMW 3 series engine - M40/42/43

The E36, developed between 1992 and 1999 displayed BMW’s desire for technological innovations. The now famous VANOS system was introduced in this era of the 3-series.

The E36 will make you an expert mechanic unwillingly with faults galore. But that hasn’t stopped hordes of fans switching from Toyota and Honda to BMW enthusiasts for the thrilling drives. This is however one of the best  BMW 3 series engines to modify.

Let’s explore the engines available in this generation…

  • M40 engine 
  • M42 engine 
  • M43 engine
  • M50 engine 
  • M52 engine
  • S50/S52 engines

The first three engines, designated as the M4x series, shared several characteristics.:

  • Configuration: Inline four cylinders
  • Displacement: 1.8-liter
  • Valve Train: Dual overhead camshaft 
  • Fuel System: Multiple fuel injection 

The 316i and 318i 3 series, were powered by the M43 engine, while the 318is and 318ti had the M42 engine.

The M4x series engines also shared a slew of problems, including.

  • Head gasket failure, which led to overheating, loss of coolant, and potential engine damage.
  • Leaks in the cooling system, beginning with the radiator, hoses, water pump, or expansion tank, caused teething heating difficulties.
  • Oil Leaks from gaskets, seals, or the valve cover.
  • Idle Control Valve (ICV) issues occur when the unit becomes dusty or fails, resulting in erratic idle speed or stalling. 
  • Electrical problems related to sensors, wiring, or the engine management system. 
  • Timing belt failure

That settles for a terrible reliability score on these engines.

Best BMW 3 series engine - M50/52

Best BMW 3 series engine - M50


The next batch of engines sharing characteristics was the M50 and M52.

They featured:

  • Configuration: six-cylinder, inline configuration
  • Displacement: 2.5 liters or 2.8 liters, depending on the specific variant
  • Valve Train: (DOHC) design
  • Fuel System: Multi-point fuel injection system
  • Power Output: The power output of the M50 engine varied depending on the specific variant. The 2.5-liter variant produced around 168 to 189 horsepower, while the 2.8-liter variant generated approximately 189 to 193 horsepower.
  • Applications: The M50 engine was primarily used in the 325i, 328i while the M52 engine was used in the E36 3 Series 320i, 323i, 328i

The M5x series reliability was greatly enhanced, which was most likely another master stroke on the inline 6. Although there were still issues with these engines, they were not as vexing. We are looking at the following:-

  • Crankcase ventilation system (CCV) failure – this can lead to excessive oil consumption, rough idling, and increased emissions.
  • Timing chain guides failure
  • Oil leaks from various gaskets, seals, or the valve cover

Overall, these are terrific engines if you can avoid the issues listed above with careful maintenance.

The M50 redeemed the BMW 3 series and remained a superb engine. To date, it is still serving some as a daily driving or project.

Best BMW 3 series engine - S50 and S52

Best BMW 3 series engine - S50


The final batch of engines was installed in the M3 performance vehicle.  Here are some key characteristics of these engines:

  • Configuration: Inline-six 
  • Displacement: The S50 engine has a displacement of 3.0 liters, while the S52 engine has a displacement of 3.2 liters.
  • Valvetrain: Both engines used a dual overhead camshaft, with two camshafts operating the intake and exhaust valves. 
  • Vanos Technology: The S50 and S52 engines incorporate BMW’s Vanos variable valve timing system. 
  • Throttle Body: These engines used an individual throttle body for each cylinder. 
  • Performance: The S50 engine produces around 240 horsepower and 225 lb-ft of torque, while the S52 engine produces approximately 240 horsepower and 236 lb-ft of torque.
  • Redline: Both engines can reach a redline of approximately 7,000 to 7,200 RPM. 
  • Applications: The S50 engine was primarily used in the E36 M3 models. The S52 engine was featured in the E36 M3 3.2

Reliability of the S50 and S52 engines

A couple of problems to report with these engines.

  • Rod bearing failure which leads to engine damage. 
  • Carbon deposits can accumulate in the intake manifold, affecting engine performance and fuel economy. 
  • Throttle body issues, mainly the throttle position sensor failures or throttle plate sticking. These can result in poor throttle response or erratic idle. 

Performance engines are only enjoyable to drive because of the adrenaline they provide. For the majority of these engines, reliability is a far stretch.

Depending on how well the engine is maintained, the S50 and S52 engines may fail you or perform exceptionally.

Caution is advised when picking either of the two engines. 

3rd Gen. BMW 3 series engines - E46 Era

Best BMW 3 series engine - E21 Era

The E46 was introduced in 1998 to 2006 . With a variety of engines, the E46 motors were designed to suit every driving style and preference. From the spirited four-cylinder engines to the powerful six-cylinder variants, these engines were built to deliver an exhilarating driving experience.

Interestingly the six-cylinder engines from this era were more reliable than the four-cylinder engines.

Let’s look at each group separately and pick the gems.

Gasoline Engines

4-cylinder gasoline engines

Best BMW 3 series engine - M43

Best BMW 3 series engine - M43

The M43 engine was potent, efficient, and powerful. Despite being a four-cylinder motor, it possessed a certain charm and character that appealed to enthusiasts and everyday drivers alike. 

The M43 featured:

  • Displacement: 1.8 to 1.9 liters (varied based on model and variant)
  • Valvetrain: DOHC (Double Overhead Camshaft)
  • Fuel System: Electronic Fuel Injection
  • Power Output: Varied across different versions, ranging from approximately 115 to 150 horsepower

Problems with the M43

One recurring problem with the M43 engine was related to the cooling system, particularly the radiator or the plastic components of the cooling system.

Another common problem reported with the M43 engine was oil leaks. These leaks were often found around the valve cover gasket, which could deteriorate and cause oil to seep out. 

Which E-46 3 series was powered by the M43 engine?

The M43 engine powered the 316i model in the E46 generation of the BMW 3 Series.

Best BMW 3 series engine - N42

The N42 engine is a four-cylinder gasoline engine produced from 2001 to 2007. It was part of BMW’s N-series engine family.

This engine featured an aluminum-magnesium cylinder block, which helped reduce the engine’s weight. That improved fuel efficiency and introduced better handling characteristics, which are essential for a dynamic driving experience.

The N42 engine came in different displacements, including 1.8 liters and 2.0 liters, depending on the specific variant and model. It offered a respectable power output, typically ranging from around 115 to 150 horsepower, depending on the model and engine configuration. 

Notable features of the N42 engine

  • Valvetronic Technology replaced the traditional throttle plate with an advanced variable valve lift system. 
  • The N42 engine had BMW’s Double-VANOS system.
  • This motor used a composite intake manifold for improved airflow and enhanced engine performance.
  • Advanced electronic engine management system to control fuel injection and ignition timing. 

The N42 engine had a direct ignition system, which eliminated the need for a distributor. Each cylinder had its ignition coil, providing precise ignition timing and improving overall engine performance.

In terms of reliability, the N42 engine generally fared well. However, there were a few common issues that some owners encountered. Most glaring, is the timing chain system. Over time, the timing chain and its associated components could experience wear, leading to timing issues and potential engine damage. 

Additionally, some owners experienced coolant leaks in the N42 engine. These leaks could occur from components such as the radiator, water pump, or expansion tank. 

Which E-46 3 series was powered by the N42 engine?

The N42 engine powered the 318i model in the E46 generation.

Best BMW 3 series engine - N46

The N46 engine is a four-cylinder petrol engine produced by BMW from 2004 to 2013. 

Notable N46 features

  • Aluminum alloy construction to improve efficiency
  • Valvetronic technology
  • Double-VANOS
  • Multi-point fuel injection or direct fuel injection, depending on the specific variant
  • Electronic engine management system
  • Dual overhead camshaft (DOHC)
  • Variable intake system
  • Low friction design to reduce internal friction. Low-friction piston rings, lightweight components, and improved lubrication systems contributed to enhanced efficiency, reduced wear, and improved power delivery.

Over time, the timing chain and its associated components could experience wear, leading to timing issues and potential engine damage. 

Another issue reported with the N46 engine was VANOS-related issues, such as rattling noises or loss of performance. 

Which E-46 3 series was powered by the N46 engine?

The N46 engine powered the 316ti Compact, 318i, and 318Ci models

6-cylinder gasoline engines

Best BMW 3 series engine - M52

The BMW M52 engine was an inline-six gasoline engine. One of the standout features of the M52 engine is the DOHC configuration and four valves per cylinder. This design allows for optimal airflow, enhancing combustion and power.

But wait, there’s more! 

Some variants of the M52 engine were equipped with Double-VANOS plus..

  • Aluminum cylinder head
  • Sequential fuel injection for improved power output, fuel efficiency
  • Electronic throttle control
  • Double overhead camshaft 
  • Low friction design
  • Drive-by-wire technology for precise throttle response and improved integration with other engine management systems 

Is the M52 reliable?

A couple of issues to be aware of with the M52; the plastic components in the cooling system, such as the radiator and expansion tank, may become brittle and become susceptible to leaks. 

Over time, the crankcase ventilation hoses and components may degrade, leading to vacuum leaks and potential loss of engine performance.

It is not an awful engine if you take care of the problems highlighted above. 

Which E-46 3 series was powered by the M52 engine?

The M52 engine powered the 323i, 325i, 328i, and 330i models.

Best BMW 3 series engine - M54

Best BMW 3 series engine - M54

The BMW M54 engine is a six-cylinder gasoline engine with impressive torque.

The motor had a range of displacements, including 2.2 liters, 2.5 liters, and 3.0 liters, depending on the specific variant and model. 

This engine churns between 170 to 231 horsepower, depending on the model and configuration.

The M54 engine closely resembles the M52 with features such as

  • VANOS technology
  • Sequential fuel injection
  • Electronic throttle control
  • Dual overhead camshaft
  • Low-Friction design
  • Drive-by-Wire technology

M54 engine problems

  • Dual-length intake manifold where the main issue is leakage from the intake’s valve affecting engine performance
  • Vanos Solenoid failure, with each solenoid costing 400 dollars in replacement
  • PCV valve failure after getting clogged up with age and usage
  • Valve Cover Oil leaks from the valve cover gaskets due to tear and wear.

A little TLC is needed to keep a 15-year-old engine running today, but the M54 was a solid build with fewer technical flaws.

Which E-46 3 series was powered by the M54 engine?

The M54 engine powered the 325i, 325Ci, 330i, and 330Ci models

Diesel Engines

Best BMW 3 series engine - M47

The BMW M47 engine is a diesel powerplant produced by BMW from the early 2000s until around 2007, and it became a popular choice for many BMW models during its lifespan.

This engine was not only powerful but the fuel consumption was at a bare minimum. These two traits made it a practical choice for those seeking a balance between performance and economy. 

The M47 engine has advanced diesel technology, such as common rail direct fuel injection, which optimizes fuel delivery for improved combustion and efficiency.

Speaking of power, the M47 engine churns a respectable output, typically ranging from around 115 to 177 horsepower, depending on the specific variant and model. 

Additional features include:

  • Common rail direct fuel injection 
  • Variable geometry turbocharger (VGT)
  • Advanced engine management system

Is the M47 Engine reliable?

One concern with the M47 engine is the swirl flaps in the intake manifold. These swirl flaps, which control airflow in the intake system, can become stuck or break over time. If this happens, it may result in reduced engine performance or potential damage. 

Over time, the timing chain and its associated components may experience wear, leading to timing issues and potential engine damage.

Which E-46 3 series was powered by the M47 engine?

In the E46 generation, the M47 engine was available in the 320d and 330d models.

Best BMW 3 series engine - M57

Best BMW 3 series engine M57

At the core of the BMW M57 engine lies a perfect balance of innovation and performance. This is the best BMW 3 series diesel engine. Let’s take a closer look at its key components.

The M57 engine’s cylinder block and pistons are made of high-quality materials and hence ensure durability and stability even under extreme conditions. 

One of the notable features of the M57 is its inline-six configuration. 

The BMW M57 engine comes in various iterations, each offering a unique blend of performance and efficiency. Let’s explore some of the notable variants:

BMW M57D30

The BMW M57D30 is a 3.0-liter inline-six diesel engine equipped with advanced technology, including variable turbine geometry (VTG) turbochargers; this variant delivers impressive acceleration and high-speed performance. 


The BMW M57T2 is an upgraded version of the M57 engine, featuring improved performance and enhanced fuel efficiency with advancements in turbocharging and fuel injection technology. 

When it comes to reliability, the M57 engine has proven to be a dependable workhorse.

But if you are planning to remap this engine, don’t do it, as this interferes with the core function of the gearbox.

M57 Engine Problems:

  • EGR valve failure
  • Water pump and thermostat issues
  • Crankcase ventilation system clogging, which can lead to turbo damage. Consider replacing it with a modern plastic CCV.
  • Glow plugs for optimal DPF function and regeneration.

Which E46 3 Series Model Featured the M57 Engine?

The M57 engine was available in the 330d model.

Wrapping up

The quest to find the best BMW 3 series engine is just as fascinating as the engines under consideration. One thing is clear, the 3 series is a terrific car – not just any typical entry-level sedan. This is a sedan with character..

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