These 6 Diesel Engines Are Practically Immortal and Built to Run for Millions of Miles

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Toyota 1HD-FTE 4.2L I6
Toyota 1HD-FTE 4.2L I6

Diesel engines have long played second fiddle to gasoline engines in the United States, largely confined to trucks and heavy-duty applications. Their popularity further declined after the 2015 Volkswagen Dieselgate scandal, which damaged public trust in diesel’s environmental promises.

Despite this, diesel engines remain invaluable in commercial sectors, where their unmatched torque and durability make them ideal for towing and hauling.

Engines like Ford’s Power Stroke or Chevrolet’s Duramax can deliver tremendous torque, sometimes reaching 1,200 lb-ft, all while maintaining solid fuel economy. In this context, some diesel engines have stood out for their extraordinary reliability and endurance.

1. Ford 6.7L Power Stroke V8: A Modern Diesel Marvel

Launched in 2011, Ford’s 6.7L Power Stroke turbo-diesel V8 powers heavy-duty Super Duty trucks like the F-250 and F-350. Designed in-house, it marked a significant leap in Ford’s diesel capability. Though early models suffered from ceramic turbo failures and Bosch fuel pump issues, these problems were rectified by 2015.

The engine’s six-bolt-per-cylinder design added durability, and with outputs up to 500 hp and 1,200 lb-ft of torque, it remains a powerhouse. When properly maintained, the Power Stroke is known to exceed hundreds of thousands of miles, cementing its place as one of the most reliable modern diesel engines.

Ford 6.7L Power Stroke V8
Ford 6.7L Power Stroke V8

2. Toyota 1HD-FTE 4.2L I6: A Global Workhorse

The Toyota 1HD-FTE, a 4.2L inline-six, is one of the most revered diesel engines globally, though it was never sold widely in the U.S. Used in vehicles like the Land Cruiser and Hilux, it’s celebrated for its bulletproof design and longevity.

Producing a modest 164 hp, it prioritizes durability over performance. Most issues stem from auxiliary components like the EGR system, not the engine block itself.

With regular timing belt changes and valve adjustments, the engine easily surpasses 500,000 miles. It embodies Toyota’s reputation for rugged reliability, especially in remote and demanding environments where failure isn’t an option.

Toyota 1HD FTE 4.2L I6
Toyota 1HD-FTE 4.2L I6

3. Chevrolet Duramax 6.6L LB7/LBZ: GM and Isuzu’s Diesel Success

Introduced in 2001, the Duramax 6.6L turbo-diesel V8 was GM’s answer to Ford’s Power Stroke, developed jointly with Isuzu. The LB7 variant brought modern features like common-rail injection and aluminum heads, though it initially faced injector failures.

These were resolved, and the later LBZ model became renowned for its toughness, incorporating stronger internal components and minimal emissions constraints. It’s not uncommon to see Duramax engines running well past 500,000 miles.

Maintenance issues are minor and typically limited to early fuel systems and EGR components. This engine series redefined diesel reliability in American pickups during the early 2000s.

Chevrolet Duramax 6.6L LB7
Chevrolet Duramax 6.6L LB7

Also Read: 5 Engines That Sound Refined and 5 That Roar Like Lawnmowers

4. International/Navistar 7.3L Power Stroke V8: The Legendary Workhorse

Ford’s original Power Stroke wasn’t even a Ford design—it was the Navistar T444E, a 7.3L V8 built for resilience. Introduced in 1994, it featured HEUI (Hydraulically Actuated Electronic Unit Injection) and robust construction, particularly post-2000 when forged internals were added.

These engines are widely admired for lasting over 500,000 miles with routine maintenance. Built before today’s restrictive emissions regulations, the 7.3L Power Stroke became synonymous with reliability in the heavy-duty truck segment.

Common issues include camshaft sensor failures and turbo up-pipe leaks, but overall, it’s regarded as nearly indestructible—a favorite among diesel truck enthusiasts even today.

Navistar 7.3L Power Stroke V8
Navistar 7.3L Power Stroke V8

5. Mercedes-Benz OM601/602/603 Series: German Diesel Engineering

Built from the 1980s into the 2000s, Mercedes-Benz’s OM601, OM602, and OM603 engines brought modular inline-four, -five, and -six configurations to vehicles like the W124. They carried forward the legacy of the OM617 by offering unparalleled reliability.

Known for running up to and beyond a million miles, these engines were praised for their mechanical simplicity and overbuilt nature. Minor issues like uneven idle or cracked heads on early OM603 models were rare exceptions.

The engines are revered for their endurance, making them highly sought after in the used market. For many, they represent the pinnacle of Mercedes diesel durability.

Mercedes Benz OM601
Mercedes-Benz OM601

6. Mercedes-Benz OM616/617 Series: The Diesel Gold Standard

Developed by Ferdinand Piëch, the OM616 and OM617 engines are often considered the most reliable diesel engines ever made. Used in the W123 and W116 Mercedes models, these inline-fours and -fives could run well over a million miles with proper care.

The 3.0L OM617 even became the first turbo-diesel engine offered in the U.S. in the 1978 Mercedes 300SD. With simple mechanical fuel injection and iron construction, their durability is unmatched.

One W123 taxi in Spain reportedly reached 4.3 million miles. Despite their age, they’re still revered today, though buyers must be wary of wear due to high mileage.

Mercedes Benz OM616
Mercedes-Benz OM616

While diesel engines face increasing regulatory pressure and shrinking market share, their reputation for durability endures—especially among heavy-duty and commercial vehicle users. From the robust Ford Power Stroke to Toyota’s global workhorse and Mercedes-Benz’s legendary inline engines, each powerplant in this list showcases engineering excellence and long-term reliability.

These engines not only withstand the demands of high mileage and heavy loads but also embody the core diesel values of torque, economy, and longevity. Despite declining mainstream popularity, these diesel legends continue to thrive in specific niches, where performance and dependability still matter most.

Also Read: 10 V8 Engines That Keep Running Strong Even After 300,000 Miles of Real-World Abuse

By Annie Linardos

I'm a journalist student and completed my masters in Journalism and Mass Communication. With a strong track record as an intern at Mathrubhumi News and The New Indian Express as a reporter and content writer, I'm creative, motivated, and have a keen eye for the truth and attempting to use the expertise and talents to contribute to the emerging field of journalism. I have also been working as a freelance writer and have the capability of producing interesting and bold articles.

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