Looking for the Most Reliable Diesel Engine?
This is a highly debated topic no matter where you look. Just like any other facet of the automotive industry, everyone has their own opinion based on their own experiences. Ford people claim Powerstroke motors are the best, Dodge people claim Cummins motor is the best and has more POWER!!, Chevy people claim the Duramax motors outperform the Dodge Cummins in the long run (But that’s been a rivalry for centuries). Here we won’t be debating the overall number one motor, but instead, provide our list of the top 10 reliable and capable diesel motors in recent years.
Our List of the Top 10 Most Reliable Diesel Engines
- 6.6L Duramax LB7
This motor was developed by Isuzu and GM back in 2001 and had a strong 4-year run being used in the Chevrolet Silverado HD and GMC Sierra HD being backed by a solid 5 speed Allison transmission. This is known as one of the most reliable motors that puts out 300HP and 520lb-ft of torque from the factory! These motors have been known to last well over the 250,000-mile markers with proper maintenance.
They also were made before the stricter rules on Diesel motors, so they don’t have to deal with Diesel Exhaust Fluid (DEF), Diesel Particulate Filter (DPF), or Selective Catalytic Reduction (SCR) problems. This helps keep the already low maintenance costs even lower, and since these common points of failure aren’t present, it helps to increase the reliability as well. They are also easier to modify with the less restrictive emissions on this motor.
This form may have only had a 4-year run, but it formed the base for the current Duramax motors that are currently released.
Helpful Tip: It is recommended for longevity to have a lift pump installed from such brands as Air Dog. We do install lift pumps as well give us a call today.
- 6.7L Power Stroke
This motor debuted in 2011 and was the first powerstroke motor to be developed and produced by Ford. Carrying the codename “Scorpion” given by engineers due to its exhaust manifold and turbocharger being mounted in the engine’s valley. This has been known as Ford’s best diesel engine yet! Producing 400hp and 800lb-ft of torque in the earlier years, while maintaining exceptional fuel economy compared to previous motors produced. Even every few years Ford kept upping the horsepower and torque to compete with other manufactures, to where the motor today produces 480hp and 1,050lb-ft of torque. They generally had no major issues frequently like the 6.4 powerstroke but usually had issues with emission related components (as every modern diesel does). Nonetheless the fuel economy city has averaged around 14mpg and 18 mpg highway.
While it may not be the top fuel-efficient truck on the road, it makes up for it with its power and reliability for the long run.
- 6.6L Duramax LP5
This is the turbo diesel GM released in 2017 for their heavy-duty pickups, and it’s kept in use today with no signs of being discontinued. This 4-valve V8 motor is running a 16 to 1 compression ratio pushing between 22 and 24lb psi of boost pressure on the stock tune, and upwards of 35 on stock internals for a more performance-based tune.
The fact that in the current tech ramp-up that the automotive industry has been going through, they’re still using this motor means that they made something special. Putting this into their more fleet-oriented vehicles means they have a strong belief in their durability and lifespan. This is still a relatively new engine, but there haven’t been many complaints or faults circling the mechanic circles, which is always promising for a potential buyer.
Even with current emission regulations this motor has proven itself to be reliable with minimal failures. Even the update of the CP4 pump to a HP4 pump, this truly gives anyone confidence in this motor.
- 6.7-Liter ISB Cummins
This is the most powerful Cummins motor produced for light and medium-duty trucks since the 5.9-liter, sitting at 350 hp and 650 lb-ft of torque. It has proven to be more than enough for day-to-day use, with the occasional big haul. These fall well with the other motors in the list, showing signs of 300,000+ miles possible on well-kept motors, this would be a strong contender for the title of “most reliable diesel”.
This model uses the same cast-iron block as the older 5.9-liter version, just with a larger bore and stroke. A 24-valve head allows it to breathe far more efficiently than its predecessor, keeping this inline-six relevant and prevalent in the diesel community. Starting back in 2007 for the earliest version, current upgrades have brought the motor to upwards of 900lb ft of torque! This has turned light and standard use vehicles into very capable haulers.
- VW 5.0L V-10
This may be a controversial entry, but a very memorable one. This 5-liter turbo V10 was in the Volkswagen Touareg and sold for a limited time in 2004 here in America due to emission regulations and was outed as one of the best SUVs you could buy due to its drivetrain and power delivery. However, it is one of the rarest motors to find compared to the 3.0 V6 TDI found in most Touaregs. This all-wheel-drive SUV put out 300hp and an incredible 530lb ft of torque (the same as current-gen Mercedes AMG’s). It was very capable as an everyday driver, and though the repair costs were expensive if anything were to happen since it was built on the Porsche chassis, it would run for a long time rarely with any issues if it were maintained properly.
Though VW has since discontinued this motor in less than a year, it was able to achieve decent fuel economy between 16 city and 20 Highway (for a V10) and had great durability as a vehicle. This motor has been able to reach upwards of 400hp and 650lb ft of torque with moderate upgrades, showing its possibilities. There are examples of it towing equivalent year Duramax trucks, showing it as a real competitor as a daily use hauling vehicle.
6. 7.3L Power Stroke
This would not be a true diesel list without naming one of the most successful diesel motors that even have Duramax and Cummins owners respecting its capability and reliability. The 7.3 Power Stroke was the first diesel to carry the Power Stroke name and replaced the old school IDI 7.3 that Ford had before. This V8 single turbo made 250 horsepower and 505lb-ft of torque, which at the time was one of the highest in its class to produce that kind of power especially if you’re hauling. What it had for reliability it lost in fuel economy with reports of 15 mpg city and 21 mpg Highway. The 7.3 being before emissions that cracked down in 2003 was ultimately one of the best trucks anyone could buy for a family hauler or a farm truck. With also being pre-emissions, it also meant none of the emissions related equipment was installed like a Diesel Particulate Filter (DPF) or Catalytic converter which also means that it was easy to modify without getting into trouble with federal laws.
The 7.3 is still viewed as one of the best diesel engines and has reports of still running today even with 400,000+ miles on the odometer.
- VW 1.9 TDI
The second VW motor to be on this list, and for good reason. This was the commuter diesel of choice for VW from mid-90’s all the way till 2006 due to its great reliability, and phenomenal fuel economy. Originally the 4th generation of Volkswagens produced in North America, started with the ALH engine code. One of the most sought after 1.9 in the family due to its mechanical fuel injection pump which made it easier for some to modify and was in most cases simpler and less prone to fail. Though it only made upward of 100 hp and 177lbft of torque, the fuel economy pushed its popularity when it received an average of 32 to 41 miles per gallon (mpg) in the city and 41 to 49 mpg on the highway. In later years of the 4th generation, Volkswagen replaced the ALH with the BEW engine code which made it no longer a mechanical fuel injection but made a stronger motor internally with rods, Crankshaft, ect. Making the motor almost a bit more powerful and bulletproof in the long run. This proves the power of a diesel as a commuter vehicle. When power or speed isn’t your concern, a small diesel can be a great way to get around affordably and overall makes for a vehicle that is built to last.
Since the only reason they stopped making this motor was due to making a larger variant of it in the later years until 2014, and not due to some major fault or problem it inherently had, it should be said that people still drive Golf and Jetta with these motors in them today (mainly in the Northwest of the states) and are very happy with its reliability and fuel economy.
- Mercedes OM617
The 70’s and 80’s was a popular time for Mercedes-Benz and already being a lead manufacturer for diesel engines for passenger vehicles they produced what is known to be one of the most motors known in the diesel community. This 3.0L 5 Cylinder motor can be found in Mercedes-Benz’s 300D and is sought after for its reliability to keep running and has been claimed to never need to be rebuilt even after putting 1,000,000 miles on it. Being a fully mechanical motor including the fuel injection, this motor produced anywhere from 80-100 hp and 130-160 ft. lbs. of torque. In later years of 1978, Mercedes-Benz added a Turbo to this motor upping the horsepower and torque as well as the fuel economy achieving anywhere from 19mpg in the city and 23mpg on the highway.
Although it may be not the fastest passenger car diesel, It still proves worthy of our list of longevity and reliability. Fun Fact: John Lennon, Former Beetles member, owned a 1979 Mercedes 300TD until he was Murdered on December 8th, 1980.
- 6.2L & 6.5L Detroit 30
This engine doesn’t get a huge spotlight but has been in a wide range of vehicles from the 1980s till 2000. It has been Gm’s backbone with the diesel seen since it first showed up in the Hummer H1, C/K pickups, K5 Blazer, Suburban, Tahoe, and Chevrolet Van if you chose the diesel variant that is. Sitting at the longest-running production in this list, it is still being produced today, almost 40 years later!
More known for its durability and reliability than its power, 190-horsepower and 380 lb-ft of torque still isn’t terrible when you consider it allowed the midsize trucks it came in to achieve mid 20mpg’s. Basic maintenance allows them to soar over the 300,000-mile mark with ease, and if you put in extra time and parts into it, you could get it all the way into the 500hp range! This motor deserves to be remembered.
- BMW B37 1.5 Liter
The only BMW on the list and for a good reason! This 3 Cylinder diesel was infamous for being the successor of the previous N47 that was prone to timing chain failures. This passenger vehicle makes a whopping 94hp and 170 lb-ft. of torque. But makes 24 City and 31 Highway (Not bad for BMW). This motor has proven itself as the high luxury vehicle that is more than capable of having the best of both worlds. Luxury and Fuel efficiency is somewhat unheard of, let alone reliability.
This motor has been reported as one of the best yet from BMW’s line up and most believe it’s their constant competition with Audi and for what it lacks in power it makes up for in reliability.
Your Trusted Diesel Mechanics
One of the overarching themes in this article is “with proper maintenance”. There is a good reason for that, just like your body, you have to care for your vehicle in order for it to perform at its best. Though many forms of maintenance can be done at home, there are some larger fixes that need special attention that are best left for trained professionals to take care of.
If you’re looking for a Portland diesel mechanic you’ve come to the right place. Here at AG Automotive, we’ve been diesel experts for over 20 years, and are very well equipped to handle any form of repair or maintenance you have.