Le Jeep – The 1985 Jeep Cherokee Diesel

The 1985 Jeep Cherokee Diesel

After decades of super cheap gasoline, people in the ‘70s and ’80s began suffering the slings and arrows of outrageous fuel prices. Wait a minute… why does that sound familiar? Anyway, gasoline quickly went from $0.35 a gallon to $1.12, and then even higher. Diesel jumped from about $0.23 per gallon to nearly a buck and then higher. It started with a Middle East oil embargo in the early ‘70s when we were still mostly buying Detroit road barges that just barely broke into double-digit miles per gallon. Talk about being caught with your pants down! Prices marched upward as the ‘70s passed into the ‘80s. Detroit scrambled to design more fuel-efficient vehicles and the import auto manufacturers got a surge of business.

The fuel economy crisis was addressed in many ways and you probably already know part of that was adding thrifty diesel to the car and truck lineups. Unfortunately, there was a lot of corporate stumbling around in the process, the Olds 350 diesel being a notorious face-plant, but there was one rig that stood out in a good light. Thirty-eight years down the road, still stands out… the Jeep Cherokee diesel.

Economy and Performance

The Jeep Cherokee XJ platform was introduced in 1984 in two guises, the top-line Wagoneer and the Cherokee, which was offered in several trim levels. They shared the same inline-four or 2.8L V6 powertrain choices and lightweight unibody construction. A Cherokee was under 3,000 pounds and even the top-line builds like the Wagoneer were only 3,200 pounds or so. Lightweight is conducive to a good economy and gives whatever engine is used the best chance of offering decent performance. The best part of the XJ line is that it also was faithful to the Jeep heritage by offering excellent stock off-road performance.

Resplendent in its original Garnet Red paint, Rick and Paulette Riley’s Cherokee model 7800 Pioneer four-door was the middle trim level in the Cherokee lineup. The Pioneer Package had a list price of $1068 for ‘85. Production records show only 1,527 of these were built in ‘85. This Pioneer is enhanced with the addition of the Sport Aluminum  Wheel option ($374).

Development of the XJ had started in the late 1970s but was on a slow track due to the red ink running all over AMC (who owned Jeep). The development of the new Jeep was speeded up by the addition of Renault as a partner. Renault of France first acquired a 22 percent share in AMC in 1980, later increasing it to 46 percent. Renault didn’t have much of a footprint here in the States but in Europe, it was a powerhouse manufacturer. There was an immediate infusion of European capital and engineering thrown into the development of the XJ and while it makes some grind their teeth, Renault added a number of technical improvements to the design. Reportedly, they also ran more than a little roughshod over their AMC and Jeep corporate partners.

The 2.1L turbo diesel is mostly aluminum and weighs in at about 300 pounds, ready to run, but for such a small engine it fills the engine compartment. It sports a 5-main crankshaft and has an overhead camshaft driven by a belt. The intercooler mounts just to the right of the radiator in a small housing. They are known by European car buffs as the Douvrin engine because they were built in northern France outside a town of that name from 1977 through 1996. A joint venture between Renault and Peugeot, the Douvrin gas engines powered a lot of European cars and light trucks in the ‘70s, 80s, and ‘90s, and a few here in the USA. The diesel variant was in production over the same period. The compression ratio was a high 21.5:1, necessary because of the indirect injection. The precombustion chamber was the Ricardo Comet V style, ubiquitous in the ‘70s and ‘80s. The diesel used a 3.38 x 3.5-inch bore and stroke, the bore being reduced and the stroke increased from the 2.0L gasser. Some of the latest variants in Europe made 91 horsepower due to turbo improvements and pump tuning.

The Cherokee was an immediate hit! For 1985, an oil burner was added to the available options and it came from across the pond in the form of a Renault 2.1L inter-cooled turbo diesel. It was available in all trim levels, including the Base, Pioneer, Chief, and Laredo, as well as the upscale Wagoneer. It could be had with any of the drivetrain options, a manual 5-speed or 3-speed automatic, and with full or part-time four-wheel drive. With the manual trans, you could enjoy 29 MPG, and the automatic delivered 23 mpg (both EPA combined ratings). The automatic diesel delivered the same EPA mpg as the manual trans gas 2.5L four.

The Renault Diesel

Europe was small-engine centric and thrifty diesel was common there in the ‘70s. As a result, they bridged the gap and made small diesel sprightly, if not sporty.  Renault J8S in the XJ. The gassers ranged from 1.9 to 2.2L displacements and they have often been praised for their output and durability. The 2.1L diesel came naturally aspirated or turbocharged but its service history is a little more problematic.

The Garrett T-2 turbo was a wastegate on the J8S-814 and a small intercooler was mounted. It operated at a max boost of 7-8 psi and the Cherokee application included a boost gauge.
A Bosch VE pump is familiar stuff to many. It delivered more than enough juice for the 2.1L diesel.

The 2.1L (126 ci) in the Jeep XJ was called the J8S-814 and it differed from the other J8S diesel in the small details, such as accessory mountings. There were also separate variants designed for either longitudinal or transverse mounting. In Jeep CJs for the Euro market, a similar J8S-800 engine was used. The J8S-814 produced 85 hp and 132 lbs-ft.  When the compact Jeep Comanche MJ pickup debuted in ’86 as a Cherokee derivative, it also had the diesel option but was only offered with a 5-speed.

The Garnet Red Mesa pattern cloth-insert seats were a $44 option over the standard all vinyl seats in the Pioneer Package. The interior is well laid out and very comfortable. The automatic is a 3-speed Model 904 Torqueflite with a lockup converter… essentially bulletproof, though the lack of overdrive is glaring when looked thru the modern point of view. The Riley’s Cherokee also has the optional Selec-Trac (NP229 transfer case), which offered a choice of rear-drive only, or all-wheel drive for the highway with a center differential and viscous coupling to lock it. Selec-Trac  Trac Cherokees also had CV-jointed front axle shafts to reduce vibration in all-wheel drive. Standard axle ratios were 3.73:1. It’s got AC and a decent sounding AM/FM radio with multiple speakers. The rear seat is folded flat to offer an impressive amount of cargo space.

In North America, besides the Jeep, the J8S powered the Winnebago Centauri, Phasar, and LeSharo compact motorhomes. It was a lot overmatched in the motorhomes. They did their best but constant flogging in a 6,000-pound motorhome was enough to give it a relatively short life. The diesel’s weak links showed up in hard use, typically with the head gasket and head bolts, and it had a tendency to crack pre chambers when allowed to get hot. The head gasket issues were solved about the time Jeep ceased using the engine.

Living With Le Jeep

At first glance, it’s easy to think, “2.1L… gotta be a toad!”  Surprisingly, they are not, though they are not hotrods. They are high reverse but when they come up onto the wastegate turbo, they buzz like a bee in a can. Rick Riley owns the ’85 Pioneer Wagon in the photos and has driven 2.8L V6  versions from the same era. “I think the diesel is just a bit faster,” he says.

Surprisingly, period magazine tests bear that out. A 2.8L V6 powered XJ 4-door delivered a 19.8 second 0-60 with 3.73 gears in Four Wheeler Magazine tests. A four-door diesel with 4.10s delivered 17.31 seconds. A 3.73 geared diesel 2-door gave a 20.1 second 0-60. All were 5-speed manuals. To compare, an ‘85 2.5L 4-cylinder gasser managed 19.8 seconds with a 5-speed. None of these times are blisteringly fast but it shows there was not much to choose between them… except in the fuel economy department.

Yeah, the 2.1L whupped the gassers hard in the economy department. Four Wheeler reported a 28 mpg combined average for the diesel with lead-footed testers behind the wheel and 16-20 mpg, or less, for the gassers, either four or six. Riley reports 28-30 mpg averages for his automatic ’85 and has seen 35 a couple of times when using a feather foot. Drivers of J8S-powered cars in Europe report 50 mpg.

The Legacy

By all reports, the J8S served well in the Cherokee, even though it didn’t sell particularly well. Yeah, the Olds 350 was still casting a dark cloud in the mid-’80s.

The Cherokee is generally responsible for keeping Jeep and AMC alive long enough for the company to be bought by a more financially healthy host… namely Chrysler Corporation… in 1987. Had AMC-Jeep been running in, or at least near to, the black, it would have put them in a very good market position. The XJ line was class-leading at its debut but short budgets slowed some of the advancements needed to keep it there.

The 2.1L Renault was offered in North American Spec Jeeps through ’87. In ’85, it was an $1124 option (compared to $300 for the V6), so it took a little while to pay off the difference via operating costs. The available production records are incomplete but indicate  329 diesel-powered XJ-based Wagoneers were built in ’85 and 3,343 2 and 4-door Cherokees. European spec Cherokees were offered with the engine to 1994. From 1990, the tweaked Euro spec J8S-890 version was offered with a variable nozzle turbo and delivered 91 hp.


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