In 1982, Mercedes-Benz unleashed its most reliable car ever, the 190E. The 190E resulted from Diamler's £600 million project to produce the bulletproof W201 and set the foundations for the W124. The 190E became the C-Class we know and love today, while the W124 was renamed the E-Class in the early '90s. Mercedes-Benz of the '70s and '80s regularly touted the phrase 'over-engineered' when marketing their products. A Greek taxi driver, Gregorios Sachinidis, proved this by taking his 1976 Mercedes-Benz 240D over 2.8 million miles!

However, today a Mercedes-Benz product has a 35.87% chance of requiring major repairs during its first ten years of service; this places them average among fellow luxury car brands. Adding further fuel to the fire is maintenance costs. For example, a product from Daimler will cost consumers around $15,986 during its first ten years in action, regarding maintenance and repairs.

Updated August 2023: We have updated this article with more reliable and unreliable Mercedes-Benz engines that you should be aware of. Mercedes, being a very old automaker, has managed to churn out some cool, reliable, and fun engines. But there are a few that you should stay away from as well.

Compare that to luxury industry leaders Lexus, who average $7,786 to maintain one of their products over the same period. Let's look at the best and worse power plants housed within a Mercedes-Benz engine bay to explain their fluctuating reputation.

All data mentioned in this list of reliable and unreliable Mercedes-Benz engines were retrieved from reputed automotive websites like CarEdge, Consumer Reports, and CarSurvey.

12 Reliable: 3.0 Inline-Five OM617

Engine Specs

Produced between 1974-1991, Mercedes-Benz loaded their 300D with a cast iron 3.0-liter diesel engine known as the OM617. A five-cylinder engine to replace the outgoing OM616 quickly garnered a reputation for reliability, with many fleet vehicles approaching 620,000 miles as time passed.

Mercedes-Benz produced 2.7 million OM617 power plants over 17 years to cement the five-cylinder's stubborn reputation as one of the best diesel engines in the world. A recent testament to Mercedes-Benz's reliability is the 1979 Mercedes-Benz 300TD wagon that went up for sale in recent years. This old Merc crossed the auction block with a whopping 782,000 miles on the clock, thanks to the OM617 housed within.

Reliability Of Mercedes-Benz OM617 Engine

• Problems Owners Report: Timing chain and fuel pump failure due to lack of periodic maintenance
• Highest Mileage Reported On CarSurvey: 272,000 miles

11 Unreliable: 2.5 V6 M272

Engine Specs

Produced between 2004-2017 to replace the M112 V6, Mercedes unleashed the entry-level 2.5-liter M272 V6 found on base-level cars such as the C230 and E230 vehicles. Producing a maximum of 201 hp and 181 lb-ft of torque, the DOHC V6 was your typical A to B power plant, or it was supposed to be.

In the early 2000s, Mercedes-Benz was undergoing a reliability crisis, and the cheaply built M272 engine block only worsened things. Timing chain issues causing premature wear to the surrounding components occurred in as little as 100,000 miles. As a result, permanent check engine lights and misfires are standard on M272-powered cars.

Mercedes-Benz had to fight off a class action lawsuit in 2010 relating to faulty components within the M272 V6 engine. However, worst of all, they even ruined the glorious S-Class with the unruly M272.

Reliability Of Mercedes-Benz M272 Engine

• Problems Owners Report: Oil leakage from cam plugs, frequent breaking of the intake manifold plastic cover, timing chain problems due to balance shaft wear
• Highest Mileage Reported On CarSurvey: 77,671 miles

RELATED: Supercharged Mercedes-Benz C230 Kompressor Jumps Dirt Hill

10 Reliable: 2.0 Inline-Four M111

Engine Specs

​​Mercedes-Benz created the M111 in 1992; the 2.0-liter four-cylinder had the impossible task of replacing the ever-dependable Mercedes OM617. As a result, the M111 found itself in the W124 E200, C200, and CLK200 Mercedes models with a maximum output of 189 hp and 199 lb-ft of torque, as featured on the gutless C200 Kompresser sports cars.

What the M111 lacked in performance, it made up for with reliability. As a result, many C200 models sporting the M111 are still on the market today. Mercedes's little cast iron block has gone on to be considered one of the best four-cylinder engines in the world for its durability and efficiency wrapped up in a tiny package.

Reliability Of Mercedes-Benz M111 Engine

• Problems Owners Report: Head gasket failures, timing chain tensioner failure
• Highest Mileage Reported On CarSurvey: 216,000 miles

9 Unreliable: 2.1 Inline-Four OM651

Engine Specs

Although Mercedes-Benz is credited today with the world's most powerful four-cylinder engine, the OM651 produced in 2008 is the exact opposite.

Mercedes released the 2.1-liter inline-four for its A, B, and low-level C-Class models. The 2.1-liter iteration produced a maximum of 201 hp. The engine's design was, so it could sit both longitudinally and transversely, increasing flexibility. There was also the issue of the Euro 5 emissions standard, which Mercedes was determined to pass. The Euro 5 emissions problem forced Mercedes to fit environmentally friendly fuel injectors; these soon failed on early iterations of the OM651 engine and were hastily replaced with electromagnetic injectors on later variants.

The compact design made the block challenging to work on. Furthermore, it could have been a more reliable Mercedes product, with regular leaks from front valve seals being a standard feature. Unfortunately, the OM651 also fell victim to timing chain failure, just as its fellow cheaply built power plants of the era.

Reliability Of The Mercedes-Benz OM651 Engine

• Problems Owners Report: Frequent glow plug servicing (after every 50,000 miles), faulty fuel injectors, timing chain failures, front valve seal leakage
• Highest Mileage Reported On CarSurvey: 114,000 miles

8 Reliable: 3.0 Inline-Six OM606

Engine Specs

Smokey Nagata had the 2JZ, and Europe had the 1993 Mercedes-Benz OM606 3.0-liter inline-six, capable of 174 hp and 243 lb-ft of torque. It is not quite a performance engine, but the stubborn diesel epitomizes reliability. Mercedes-Benz produced the block between 1993 and 2001, featuring it exclusively in the automakers' premium E, G, and S-Class range. Tuners were also keen to get their hands on the modest diesel engine, taking figures up to 500 hp with the help of a turbocharger.

The OM606 is widely regarded as one of the most bulletproof inline-six engines in the world, provided you change up the glow plugs occasionally.

Reliability Of The Mercedes-Benz OM606 Engine

• Problems Owners Report: Glow plug failure
• Highest Mileage Reported On CarSurvey: 60,000 miles

7 Unreliable: 3.0 V6 OM642

Engine Specs

Mercedes produced the 3.0-liter V6 named the OM642 in 2005, and the six-cylinder successfully featured up until 2018 on the E350D.

The OM642 had two jobs, powering Gwen Stefani's G-Wagon, and tackling emissions standards by replacing the current straight-five and six-engine lineup. The 3.0-liter Mercedes engine was featured in Chrysler products, such as the Jeep Commander and 300C until Daimler and Chrysler parted ways in 2007.

What ruined the engine's reputation was a combination of low-quality gaskets, deteriorating ventilation valves, and of course, the 2018 recall surrounding emissions regulations. Furthermore, the OM642 also sported environmentally friendly Piezo injectors. Sadly, the polar-bear-friendly injectors regularly failed and caused black exhaust fumes on OM642-powered cars.

Reliability Of The Mercedes-Benz OM642 Engine

• Problems Owners Report: Melting of engine-layered plastics due to high temperatures from wear of crankcase ventilation valve, black smoke due to non-replacement of Piezo injectors, manufacturing of fuel flow control valve, low quality gaskets cause oil leaks in the engine block for engines manufactured before 2010.
• Highest Mileage Reported On CarSurvey: N/A

6 Reliable: 4.2 V8 M116

Engine Specs

Mercedes produced the M116 V8 between 1969 and 1991 to win over the American markets. The rigid cast iron block appeared on the longest-running S-Class series, providing the luxury sedan 228 hp mated to a Mercedes-Benz 4G-Tronic gearbox.

The 4.2-liter M116 is also featured on the highly reliable Mercedes-Benz SL420 (R107). In fact, the SL420 is the rarest of its kind. Only 2,148 models arrived with the sturdy 4.2-liter V8 power plant; prices for an R107 SL420 average around $35,238 today. The tried and tested M116 engine in 4.2-liter format was the penultimate iteration of the V8 engine block, which saw replacement in 1991 with the 4.2-liter DOHC M119.

Reliability Of The Mercedes-Benz M116 Engine

• Problems Owners Report: Timing chain issues, camshaft wear, worn-out valve guides.
• Highest Mileage Reported On CarSurvey: N/A

RELATED: Here's Why Mercedes Is Killing All Its V8s

5 Unreliable: 5.4 V8 M273

Engine Specs

The 'performance' variant of the equally poor M272 V6 was a 5.5-liter iteration aptly named the M273. Produced between 2006-2013, the M273 dumped its 5.5-liter frame under the hood of various models under the moniker 500 or 550. A maximum power figure of 382 hp and 391 lb-ft of torque made the block look appealing on paper. However, familiar problems stalked the M273 engine.

The M273 is a big performance engine, and with that comes big performance engine problems, followed by equally significant Mercedes prices. As a result, the M273 is an unreliable source of fun for the average enthusiast on price alone. Issues such as deteriorating dampers in the intake manifold can lead to a complete engine rebuild, while turbocharger failure is also common.

Reliability Of The Mercedes-Benz M273 Engine

• Problems Owners Report: Oil leakage from the cam plug, poor quality of intake manifold plastic level, Timing chain problems, secondary pump failure, overheating due to engine thermostat failure, oil leaks from camshaft magnets for cars with over 50,000 miles
• Highest Mileage Reported On CarSurvey: 77,670 miles

4 Reliable: 2.6-Liter Inline-Six M103

Engine Specs

The mid-80s saw Mercedes-Benz come into its own with the impenetrable W201 190E and W124 models, later known as the C and the E-Class sedans. Both vehicles are considered the most reliable cars ever made by Mercedes-Benz, and both drew power from the equally dependable 2.6-liter six-cylinder M103 motor.

Thanks to its simplistic, over-engineered nature, the humble little block maxed out at 166 hp and 128 lb-ft of torque and could regularly cross over 200,000 miles and beyond. Mercedes-Benz created the W201 190E due to a £600 million project that transformed the company's reputation for robust and dependable motor vehicles, and the M103 was one of its most reliable engines.

Reliability Of The Mercedes-Benz M103 Engine

• Problems Owners Report: Oil leaks, timing chain failure, head gasket failure
• Highest Mileage Reported On CarSurvey: 222,000 miles

3 Unreliable: 1.8-Liter Inline-Four M271

Engine Specs

Arriving between 2002-2011 is the minor M2 engine-coded product. The 1.8-liter M271 found on entry-level Mercs could produce a maximum of 201 hp. The engine lurks beneath the Mercedes-Benz C, E, and SLK models.

The M271 is an early 2000s Mercedes-Benz product and shares the typical unreliable characteristics of the company at the time. Aside from notoriously leaky gaskets, the M271 shares similar timing chain issues to its larger displacement cousins, often leading to a hefty bill when the chain is stretched beyond engine knocking and misfiring, ultimately leading to piston damage, forcing a complete rebuild.

Reliability Of The Mercedes-Benz M271 Engine

• Problems Owners Report: Power loss due to soot on valve stems, engine noise
• Highest Mileage Reported On CarSurvey: N/A

2 Reliable: 3.0-Liter Inline-6 OM603 Engine

Engine Specs

Diesel engines are a mess when it comes to emissions. But we can't deny the fact that a dependable, tough, and fuel-efficient diesel engine will never falter. The OM603 inline-6 diesel engine from Mercedes-Benz is a testimony to the same. People love this motor that had its run from 1986 to 1997. Despite its characteristics to be worthy of being plonked into a G-Class, this robust diesel engine was actually used in various Mercedes luxury sedans like the W124, W125, and W140 Series.

Reliability Of The Mercedes-Benz OM603 Engine

• Problems Owners Report: Injector pump leakage, broken injector pipe holder
• Highest Mileage Reported On CarSurvey: 210,000 miles

1 Unreliable: 6.3-Liter V8 M156

Engine Specs

When we talk about a Mercedes-AMG engine, performance and wild acceleration figures are what come to mind. But the 6.2/6.3-Liter V8 M156 Mercedes engine loses out on its fun factor because of a poor reliability record. This engine is used in various Mercedes-AMG cars from 2006-2015. This engine is high on horsepower and packs performance figures with up to 622 hp. Notable cars that pack the M156 engine include the AMG models sold between 2007 and 2011, like the E63 AMG, the ML63 AMG, the CLS63 AMG, the CL63 AMG, and also the S63 AMG.

Reliability Of The Mercedes-Benz M156 Engine

• Problems Owners Report: Failing camshaft system, corroded intake manifold, malfunctioning injectors
• Highest Mileage Reported On CarSurvey: N/A