Diesel engines are known for making big torque right off the line, and their overall fuel efficiency and simplicity make for long, reliable running. As such, it’s surprising that more Jeeps haven’t been fit with oil-burning engines. Many Jeep owners run their vehicles off-road, where repair facilities and fuel stations are non-existent. Additionally, a diesel’s high relative torque would make turning large tires at slow speeds a cinch.
Americans’ general distrust of diesel is an anomaly not shared with the rest of the world. In 2002 we drove a Jeep Grand Cherokee WJ equipped with a 2.7L turbocharged common-rail diesel I-5 supplied by Mercedes-Benz. We liked its smooth performance and improved fuel economy, and we weren’t surprised to learn it was a very popular vehicle for Europeans, who are typically U.S.-averse when it comes to cars. The same platform was also available with a 3.1L VM Motori I-5 turbodiesel, while its little brother, the Jeep Cherokee XJ, could be had on the Continent with a 2.5L turbodiesel I-4. And today, every Jeep available in Europe can be optioned with a diesel engine, including the contemporary Renegade, Wrangler, and Cherokee.
While our shores have been relatively bereft of Jeep diesel options, there have been a few notable domestic-market production models, as listed below. Which is your favorite?
1956-1965 Jeep M676/M677/M678/M679
Technically speaking, this Jeep isn’t a production vehicle, since it was only manufactured for military use. But this variation of the legendary Jeep Forward Control is still a notable vehicle. It used an obscure Cerlist two-stroke, inline-three diesel engine that produced a reasonable 170 lb-ft of torque from 170 cubic inches, or 2.8 liters, of displacement. Although it was less powerful and slower than the gas I-6 installed in the civilian Jeep FC-170, it was much more reliable, partly due to diesel’s inherent durability and partly to the mechanical simplicity afforded by a two-stroke engine.
This Jeep M677 Forward Control is a military-only model, featuring the FC170's platform, a crew-cab body, and a very unusual diesel engine.
1961-1968 Jeep CJ-5/CJ-6 Perkins
The first civilian Jeep diesel on offer (that we can find, anyway) was the 1961 Jeep CJ-5. A rare option for that year was the Perkins 4.192 diesel engine.
As the name suggests, this inline-four diesel displaced 192 cubic inches (or 3.1 liters), and it enjoyed a healthy 58 hp and 143 lb-ft. Offered until 1968, later Perkins developed up to 65 hp, which was good for a top speed that mirrored that of the gas I-4 model and fuel efficiency of up to 30 mpg, exceptional for any vehicle of the era, much less a trucky off-roader. Around 2,000 were produced, and luckily, rarity doesn’t breed value in this case, as the price premium for a Perkins is insignificant.
The Jeep you see here belongs to Jon Stoltzfus of Pennsylvania, and it acquired only 13,000 miles on a Pennsylvania farm before being parked in a barn for 15 years. It was dragged out of the barn, painted, rewired, and put up for sale. Jon bought it from the original owners seven years ago. It’s more or less like he got it here, but Jon added a Newgren low-profile three-point hitch, Jeep PTO, and Newgren saw, along with a front weight and chaff screen. It has the optional ventilating windshield.
1981-1985 Jeep CJ-10
This one’s another stretch, but since the Australian-market Jeep CJ-10
eventually spawned an America-bound aircraft tug model, we’ll include it. The CJ-10 featured a 3.3L naturally aspirated diesel I-6 sourced from Nissan, producing 90 hp and 138 lb-ft. The CJ-10 got the rest of its bones from the contemporary J-10 fullsize pickup, featuring that model’s proportions but with Jeep CJ styling. It’s an odd look, for sure, and with fullsize-truck curb weight and compact-car power output, this is a model that we’ll enjoy as a fun piece of history, not a daily driver. Nevertheless, it still enjoys that old-Jeep dependability, amplified by its reliable diesel powertrain, and as such, it made an excellent low-speed aircraft tug used by the United States Air Force. That model carries the CJ-10A appellation.
This very rare CJ-10 survivor belongs to Steve Hendricks. It’s a 6,700-pound GVW unit with the 3.3L diesel and automatic. It’s wearing Wrangler half doors because the stock doors were still under restoration at photo time and needed some hard-to-find repair parts.
1985-1987 Jeep Cherokee/Comanche
The Jeep Cherokee and Comanche XJ have a loyal enthusiast following, but their available Peugeot-designed 2.1L turbodiesel I-4, not so much. Its 85 hp and 132 lb-ft were dwarfed by every other XJ engine, including the much maligned carbureted 2.5L AMC I-4. Since the 2.1L diesel is derived from a 2.0L Peugeot gas engine, its reliability suffered as well. With less torque and substantial reliability concerns, the diesel engine’s usual advantages weren’t on display in the XJ. Luckily for the world, it was replaced by the much better 2.5L VM Motori diesel engine for export markets in 1994. Unluckily for us, it was never sold in the United States.
2005-2006 Jeep Liberty CRD
After the departure of the Cherokee diesel, America went nearly 20 years without enjoying an oil-burning Jeep. That losing streak ended in 2005 when the Jeep Liberty became available with a 2.8L inline-four manufactured by VM Motori. The engine made 160 hp and 295 lb-ft of torque, and they were EPA-rated at 19/24 mpg city/highway. The high torque output and slightly improved fuel efficiency made them attractive options to some, but others were turned off by the noisy, clattery diesel. It wasn’t sold in California or New York, and it was discontinued after two years on the market due to emissions noncompliance. Still, it sold in reasonable numbers, and it enjoys a devoted enthusiast following, of which we’re a part.
Our Jeep Liberty CRD project vehicle routinely saw fuel economy numbers in the high 20s.
2007-2009 Jeep Grand Cherokee CRD
Immediately after the demise of the Liberty CRD, Jeep made amends with the Grand Cherokee CRD. Powered by a Mercedes-Benz 3.0L common-rail turbodiesel V-6, its 198 hp and 371 lb-ft gave it more than enough muscle to go off-roading and tow family toys. At the time, we called it the best midsize SUV
money could buy, and while in hindsight we may have been a bit overzealous with that distinction, it was nevertheless a uniquely capable take on the Grand Cherokee name.
2014-present Jeep Grand Cherokee EcoDiesel
The vehicle that arguably convinced Jeep that America was ready for a diesel Wrangler is this, the Jeep Grand Cherokee EcoDiesel. Bringing VM Motori back on board, the EcoDiesel enjoys 240 hp and 420 lb-ft of torque thanks to the engine manufacturer’s 3.0L turbodiesel V-6. We’ve got almost nothing bad to say about the EcoDiesel, with most of our complaints centering around Jeep’s unfortunate air-suspension tuning off-road. In terms of the engine, we’ve got nothing bad to say. Our long-term Grand Cherokee Overland
got amazing fuel economy; had impressively low levels of noise, vibration, and harshness; and performed well on the highway, off-road trail, and while towing.
Sources: The FC Connection, OffRoaders.com