Diesel engines never gained the same widespread acceptance in American passenger cars as they did in Europe, primarily due to stringent emissions standards and consumer preference for gasoline.
Their popularity took a sharp hit after the 2015 Volkswagen Dieselgate scandal, which tarnished public trust in diesel technology. Today, diesel is mainly found in heavy-duty trucks and commercial vehicles, where its torque and fuel efficiency shine.
These vehicles, like the Ford 6.7L Power Stroke, offer massive torque figures, making them ideal for towing and hauling while still maintaining reasonable fuel economy in long-haul or work-based usage.
Creating a definitive list of the most reliable diesel engines is tricky due to the many variables involved—owner maintenance habits, climate, and application all matter.
The list compiled considers data from RepairPal and CarComplaints while acknowledging that even engines with minor recurring issues can still be incredibly durable when properly maintained.
Despite differences in reliability metrics, every engine featured has earned a reputation for long-term dependability, especially with proactive care. No engine here is a dud; all are known for logging high mileage and dependable service, even if certain components or emissions systems need occasional attention.
1. BMW M57 3.0L I6: Performance Meets Longevity
The BMW M57 3.0L diesel engine delivered performance and durability in models like the 3, 5, and 7 Series and SUVs like the X5. Known for its smooth delivery and robust internals, this engine can last hundreds of thousands of miles.
However, emissions components—particularly the EGR, DPF, and turbo seals—often require maintenance or replacement. Problems like crank damper failure or cooling system leaks may arise, but the hard parts remain dependable with routine care.
Proper use, such as regular highway driving, can help mitigate emissions-related issues, extending engine life significantly for BMW diesel enthusiasts.
2. Volvo D5 2.4L I5: Scandinavian Toughness
Volvo’s D5 engine, based on its modular gas engine architecture, is an inline-five diesel used in models like the S60 and XC90. It combines a strong aluminum block with iron liners to withstand diesel combustion pressures.
Known for smoothness and torque, these engines commonly exceed 200,000 miles, with higher figures possible through rigorous maintenance.
Key issues include failing engine cooling fans, fuel line leaks, and timing belt failures, the latter of which can be catastrophic. With proper upkeep, including timely belt changes, the D5 remains one of the more resilient European diesel options available in the U.S. market.
3. VW Group EA827 TDI: Economical and Enduring
The VW Group’s 1.9 and 2.0 TDI engines are among the most recognized diesel units in the U.S. market, despite the shadow of Dieselgate. Known for their excellent fuel efficiency and solid engineering, these engines have powered millions of Golfs, Jettas, and Audis.
The 1.9L version is particularly celebrated for longevity, though noisy, while the 2.0L added more refinement. Regular timing belt replacements are essential, and owners should be vigilant about EGR issues and dual-mass flywheel failures.
With consistent maintenance, these TDIs can easily run past 300,000 miles, offering economical operation without sacrificing reliability.
4. Ram HD Cummins ISB: Legendary Inline Six
The Cummins ISB engine, especially in its 5.9L and 6.7L variants, is a legend in the diesel truck community. Used in Ram HD trucks, this inline-six offers brute torque and remarkable reliability.
Originating in the 1980s, these engines evolved with 24-valve heads and common-rail injection. Issues like VP44 pump failure or turbo vane sticking do occur, especially in early models, but the core engine remains almost bulletproof.
With proper servicing and attention to emissions gear, these engines are known to surpass 350,000 miles with ease. They’re a top pick for heavy-duty use thanks to their simplicity and endurance.
5. Ford 6.7L Power Stroke V8: Modern Muscle
Ford’s 6.7L Power Stroke engine, developed in-house and launched in 2011, represents a major leap in diesel engine design for the brand. Used in F-250 and F-350 Super Duty trucks, it delivers up to 1,200 lb-ft of torque.
Early issues, like failing ceramic ball-bearing turbos and weak Bosch CP4.2 fuel pumps, were addressed by 2015. Later models proved much more reliable, with strong head gaskets and improved EGR systems.
This engine thrives on maintenance, and with regular oil changes and cooling system checks, it’s easily capable of crossing the 400,000-mile threshold, making it ideal for power-intensive applications.
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6. Toyota 1HD-FTE 4.2L I6: Built for Endurance
The Toyota 1HD-FTE engine, a straight-six turbodiesel found in Land Cruisers and Hilux models, is revered globally for its reliability and ruggedness. Though not commonly sold in the U.S., imported models have earned cult followings.
These engines routinely reach half a million miles, with timing belt maintenance and EGR cleaning among the most pressing maintenance tasks. Valve clearance checks every 40,000 miles are also advised.
The simplicity of the mechanical fuel system contributes to the engine’s bulletproof reputation. It’s a favorite in off-road and expedition communities thanks to its durability under extreme conditions and low-end torque.
7. Chevrolet Duramax LB7/LBZ V8: GM’s Diesel Workhorse
Chevrolet’s LB7 and LBZ 6.6L Duramax engines, developed with Isuzu, marked GM’s entry into the modern diesel race. Found in Silverado and Sierra HD trucks, the LB7 featured common-rail injection and aluminum heads, while the LBZ improved with stronger internals and fewer emissions constraints.
Though early LB7 injectors and fuel filter housings had issues, these were fixed in later versions. Both engines are renowned for their durability and smooth operation, with many trucks reaching 500,000 miles or more.
Their performance, simplicity, and aftermarket support make them favorites among diesel truck enthusiasts and heavy haulers alike.
8. Ford 7.3L Power Stroke V8 (T444E): Old-School Reliability
The 7.3L Power Stroke, based on International Navistar’s T444E, is one of the most trusted diesel engines ever made. Found in Ford Super Duty trucks from 1994 to 2004, it used HEUI (Hydraulic Electronic Unit Injector) technology and forged internals for unbeatable strength.
Known for running beyond 500,000 miles, especially post-1997 models, it has a loyal following. Its all-iron construction and hydraulic lifters made it durable and low-maintenance.
Problems like CPS sensor failure or up-pipe leaks are manageable and well-documented. This engine’s simplicity and toughness solidify its place as a diesel icon in the truck world.
9. Mercedes OM60x Family: Million-Mile Machines
The Mercedes-Benz OM601, OM602, and OM603 engine family represents a peak in diesel longevity. Used from the early ’80s to 2000, these engines powered models like the W124 and were available in inline-4, -5, and -6 configurations.
Renowned for smooth operation and high-mileage capabilities, many units have exceeded one million miles. The modular design simplified maintenance, although early OM603s had issues with cracked heads and bent rods.
Still, these engines are highly regarded for their indestructible architecture and minimal maintenance needs, often seen in enthusiast-owned W124s and older Mercedes sedans still running decades after leaving the factory.
10. Mercedes OM616/OM617: Diesel’s Gold Standard
Considered the most reliable diesel engines ever made, the OM616 and OM617 power many W123 and W116 Mercedes-Benz models from the 1970s and ’80s. Designed by Ferdinand Piëch, these naturally aspirated and turbocharged engines are known for reaching over one million miles, with some taxis even exceeding 4.3 million miles.
Producing modest horsepower, these engines prioritize durability and ease of maintenance. Regular oil changes, valve adjustments, and fuel system upkeep are enough to keep them running indefinitely.
Although now old, their simplicity, overengineering, and parts availability keep them on the road and celebrated among diesel purists.
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