Diesel engines have long struggled to gain popularity in the U.S., primarily finding favor in heavy-duty trucks. The fallout from Volkswagen’s 2015 Dieselgate scandal only worsened diesel’s image, restricting it mostly to commercial and towing applications.
Despite the stigma, diesel engines remain prized for their fuel efficiency and ability to generate substantial torque, making them essential for towing and long-haul work.
Outside of the mainstream consumer market, diesel technology has advanced and proven remarkably durable. This article highlights some of the most reliable diesel engines ever sold in the U.S., backed by performance data and real-world reliability records.
1. BMW M57: German Power with Longevity
BMW’s M57 3.0L inline-six diesel engine, found in models like the 335d and X5, is a strong performer known for both smooth operation and reliability. While emissions systems like the EGR and DPF can create issues over time, the core engine is capable of running for hundreds of thousands of miles with proper care.
Common problems include leaks, failed thermostats, and crank damper issues. Regular highway driving helps keep the emissions systems healthy. Though not the cheapest to maintain, especially in older BMWs, the M57 remains a solid, long-lasting diesel choice when maintained diligently.
2. Volvo D5: Scandinavian Strength
Volvo’s 2.4L D5 diesel, used in models such as the S60 and XC90, is based on a solid closed-deck design that can easily handle high combustion pressures. With routine maintenance, including timely timing belt replacements and attention to oil consumption, these engines can last well over 200,000 miles.
Common failure points are related to auxiliary systems, including electric cooling fans and fuel lines. The D5 balances decent power with fuel efficiency, and its solid block design lends itself to impressive durability. Volvo’s engineering resulted in a reliable and refined diesel for family cars and SUVs alike.
3. VW Group EA827 TDI: Economical and Dependable
The VW Group’s EA827 diesel engines, particularly the 1.9L and 2.0L TDIs, are among the most widely used diesels in U.S. compact cars. Found in models like the Jetta and Golf, these engines are efficient and rugged. Though the early 1.9L is noisy, it’s long-lasting with simple maintenance.
The more modern 2.0L added 16 valves and better performance but introduced more emissions complexity. Frequent concerns include EGR valve and timing belt issues. With the right care, these engines routinely exceed 300,000 miles, offering great fuel economy and low repair costs—when maintained carefully.
4. Cummins ISB: The Heart of Ram Trucks
The Cummins ISB inline-six diesel, used in Ram HD trucks since 1998, is known for exceptional torque and bulletproof reliability. Available in 5.9L and 6.7L versions, these engines can surpass 350,000 miles easily.
The 5.9L engine is especially praised for its simplicity and longevity, while the 6.7L added emissions controls that introduced some complications. Owners should watch for issues like VP44 injector pump failure and turbocharger vane sticking.
Despite these, Cummins’ durability and consistent upgrades keep these engines among the most trusted in heavy-duty applications and long-distance towing.
5. Ford Power Stroke 6.7L: Built In-House, Built Tough
Introduced in 2011, Ford’s in-house 6.7L Power Stroke V8 turbo-diesel engine powers Super Duty trucks like the F-250 and F-350. Its aluminum heads, iron block, and six-bolt-per-cylinder design contribute to its strength.
Early models had issues with ceramic ball-bearing turbochargers and Bosch CP4.2 fuel pumps, both of which were addressed by 2015. Current versions produce up to 1,200 lb-ft of torque. Common concerns now include head-gasket and EGR valve failures.
With those addressed, this engine is known to deliver reliable power and longevity, making it a cornerstone of Ford’s heavy-duty truck lineup.
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6. Toyota 1HD-FTE: Diesel That Won’t Die
The 4.2L inline-six 1HD-FTE diesel, mainly used in Toyota’s Land Cruiser and Hilux, is a legend of durability. Though never sold in U.S. passenger vehicles, it is widely known globally for surviving harsh conditions and clocking hundreds of thousands of miles. Its relatively low power output belies the engine’s robustness.
Routine maintenance, such as valve clearance checks and timing belt replacements, is essential. Its mechanical fuel injection and simple emissions systems keep repair complexity low. Emissions-related issues like EGR clogging can occur but are manageable. It’s considered one of Toyota’s finest diesel efforts.
7. Duramax LB7/LBZ: GM’s Diesel Game-Changer
The 6.6L Duramax V8 diesel, developed jointly by GM and Isuzu, marked a major advancement in diesel performance. The LB7 (2001-2004) and LBZ (2006-2007) variants are especially prized by diesel enthusiasts for their robust design and minimal emissions restrictions.
With forged internals and advanced fuel injection systems, these engines can achieve over 500,000 miles. The LB7 had early injector problems, while the LBZ was more refined and powerful.
Minimal EGR complexity in the LBZ contributed to its reliability. These engines continue to power Silverado and Sierra trucks with strength and dependability.
8. Navistar 7.3L Power Stroke: Ford’s First Diesel Legend
The 7.3L Power Stroke V8, designed by International Navistar and used in Ford trucks from 1994 to 2004, has become legendary for its toughness. Known for lasting over 500,000 miles, the all-iron engine employed HEUI fuel injection and required minimal maintenance.
Common issues include camshaft position sensor failure and leaking up-pipes, but they rarely result in catastrophic failure. Its mechanical simplicity and durability earned it a devoted following, and many of these engines are still on the road today. The 7.3L is widely considered one of the most reliable diesel engines Ford ever used.
9. Mercedes OM60x Series: Built to Last
The OM601, OM602, and OM603 series from Mercedes-Benz built on the brand’s legacy of diesel reliability. These modular inline-four, five, and six-cylinder engines were used in models like the W124 E-Class. Although more complex than the earlier OM617, they maintained remarkable durability.
Many have crossed the million-mile mark. Known issues include cracked cylinder heads and bent rods, particularly in early OM603 engines. However, with proper cooling and maintenance, these engines are known to run for decades. Their longevity continues to make them a favorite among Mercedes diesel fans around the world.
10. Mercedes OM616/OM617: The Diesel Benchmark
Designed by Ferdinand Piëch, the OM616/OM617 engines are often considered the most reliable diesels ever made. These inline-four and inline-five engines powered Mercedes sedans like the W123 and W116 through the 1970s and ’80s.
With simple mechanical fuel injection and tank-like construction, they frequently exceed 500,000 miles—with some reportedly surpassing 4 million. Their minimal electronics and straightforward design make them easy to maintain.
While aging has caught up with most of these engines, they remain a testament to Mercedes’ engineering prowess and remain popular among enthusiasts seeking indestructible vintage diesel cars.
Despite public skepticism and regulatory pressures, diesel engines have built a legacy of rugged reliability in many applications. From early mechanical designs to more complex electronically controlled models, these engines prove that with good design and regular maintenance, high-mileage performance is entirely possible.
While emissions systems remain a weak point in modern diesels, the core mechanical components in these engines are often incredibly robust. Whether used in passenger vehicles or heavy-duty trucks, the best diesel engines combine economy, torque, and longevity in ways that few gasoline engines can match.
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