Dodge’s Diesel Trucks Were Nothing Before Cummins

Has there ever been a more American marriage than Dodge and Cummins? The trucks are called Rams now, but the coupling remains a strong one. The engine manufacturer has offered variety of different diesels over the years, with the beloved Cummins 6BT winning legions of fans since it first appeared in the D Series trucks in 1989. But the Cummins was not Dodge’s first attempt at building a diesel pickup. Dodge had at least one, and maybe two false starts before that!

Dodge’s journey into the diesel world has been quite unlike its Big Three rivals. Both Ford and Chevy have pursued their own diesel programs over the years; Ford in particular has had the most success with its in-house designs. Dodge, on the other hand, has primarily looked to outside partners. It’s done wonderful things with Cummins over the past three decades, but before that, it had much less success buying in engines from other sources.

Yes, prior to finding its current diesel life partner, Dodge’s trucks relied on engines from Japan and even Britain. Let’s look at its super-obscure first attempt, and its more well-known effort amidst the fuel crises of the 1970s.

60s Diesel Obscura

Chevy’s godawful diesel C10 is often cited as the first major American pickup with a diesel engine. However, Dodge might just have beaten it by a full decade. It’s actually so obscure that it’s difficult to find definitive information on just where and when its first diesel pickup was available. What we do know is that around 1962, Dodge offered a Perkins 6.354 diesel engine in certain models of the D Series truck. But could you get it in a pickup, or just the larger commercial models?

For a straight six, The Perkins engine had a massive 354 cubic-inch displacement, or 5.8 liters. The engine was seen in Dodge’s heavy-duty trucks, too, but its time in the D Series was short. It was primarily available on the Dodge Diesel PD500 and PD600, which weren’t really pickup trucks so much as conventional cab trucks for coach builders. The engine was good for 120 hp and 260 pound-feet of torque in those applications.

However, there is at least one W300 out there featuring this engine. If you’re unfamiliar, that’s the four-wheel-drive version of the D Series. As covered on Sweptline.com, that truck currently has a bed, but was originally equipped for pulling horses. Thus, it’s not clear if this was an early qualifier for the first American diesel pickup, given it wasn’t really a mainstream offering.

[Mercedes’ Note: Perhaps even more obscure than the ’60s Dodge Perkins diesels is when International Harvester launched a compact, thrifty diesel engine at roughly the same time. The folks of IH saw the growing popularity of diesel in the medium-duty market and decided to offer diesel engines as options in its C-Line of the early 1960s. These, like the ’60s diesel Dodges, appear to be outrageously rare. – MS]

I’ve also found one other example of a W300 that the owner claims as having the Perkins engine. My research suggests the Perkins diesel may have been a special order option. That is, you could have one if you really wanted one in the W300 and D400. In any case, the Perkins diesel wasn’t marketed for pickups in any way that I’ve seen, and the D Series quickly moved on. It wasn’t really a serious attempt by Dodge to establish diesel engines for mainstream pickup trucks.

The First (Real) Attempt

Cut to the 1970s. The first gas crisis struck, everybody went buck wild over gas line, and was freaking out about the cost of fuel. Diesel seemed to be the ideal solution. A diesel engine could provide good torque and much improved fuel economy over a gasoline engine, and at the time, diesel was cheaper to boot. To take advantage of this, Dodge just needed an engine.

At the time, Chevy had a bunch of engineers fumbling around with a gas V8 to make it into a diesel, but Dodge decided to grab something off the shelf. Chrysler already owned 15% of Mitsubishi, so tapping the Japanese automaker for a diesel engine made perfect sense.

Dodge ended up selecting the Mitsubishi 6DR5. The 4.0-liter (243 cubic-inch) naturally-aspirated inline-six featured in Mitsubishi’s Fuso trucks and even forklifts in a low-power version, but now it would star in the Dodge D Series, too. In the American pickups, it ran a 20:1 compression ratio—typical for a diesel—and offered 105 horsepower and 169 pound-feet of torque. To make it suit the pickup application, Dodge simply created an adapter plate which would allow the Mitsubishi engine to bolt on to manual and automatic transmissions that used the LA V8 bolt pattern.

The diesel was available on a wide range of models right from the drop. Initially, it could be had in the D150 and D200 pickups, along with the W150 and W200 four-wheel-drive versions. You were out of luck if you lived in California, though—Dodge didn’t offer the diesel there. In 1979, Dodge brochures indicate a wider rollout, with the D100, B100, B200, and B300 also able to be optioned with the Mitsubishi diesel.

Whether any D100s or B Series vans ever got the engine is a question I haven’t been able to answer, however. Various anecdotes around the Internet state that the option was dropped for 1979, which could have happened after brochures were finalized and printed. I have just one hint that a diesel B Series van actually got built, and that’s the fact that numerous parts sites list a “Diesel Glow Plug Relay” for the 1979 Dodge B300. It could just be a regular relay that’s mislabeled or something, but it’s a tantalizing hint as to what might be out there.

The engine ran well enough, lacking any major reliability issues or headline problems. That’s unsurprising, given it was an established design. Nevertheless, Dodge’s first proper diesel truck suffered in the marketplace. It was seen as underpowered and thus unsuitable for an American market pickup. Dodge also didn’t make a big hullabaloo about the diesel option. Where Chevy had plastered its new diesel option across all its brochures, and most of its passenger car fleet, the Dodge diesel option was more of a footnote in marketing materials.

Contemporary sources note this fact as well. In the June 1978 edition of Motor Trend, the outlet noted that “All the press on General Motor’s 350 V8 diesel tends somewhat to shade the fact that Dodge has also introduced a diesel in their light truck line for ’78.” The outlet devoted three pages to a review of the 1978 Dodge W150 Power Wagon with the Mitsubishi engine. It noted the truck was “quite a handful to drive on city streets and in many off-road situations,” putting the problem down to the wide gaps between ratios of the four-speed manual. The outlet noted the 3-speed automatic was probably a better choice.

First gear was strictly a stump-puller, with a top speed of close to five miles per hour. The remaining gear ratios were widely spaced so that the engine dropped to almsot an idle when switching to the next gear up, while downshifting created a reverse problem—you’d catch the lower gear near peak rpm, which made it almost useless.
Bob Kovacik, Motor Trend, June 1978

In the magazine test, the truck achieved a 0-60 mph time of 27.0 seconds. Again, the poor ratios of the manual were claimed to be at fault here, with an automatic model expected to be much faster. Typical pickups of the time weren’t fast, but they’d generally get to 60 mph in under 20 seconds without too much trouble. It’s a hilarious statistic, given the Dodge Lil’ Red Express pickup was, in 1978, the fastest American production vehicle with a zero-to-6o mph time of just 6.7 seconds by comparison, by virtue of its big V8 engine and a loophole that allowed it to run with no catalytic converters.

Starting the truck was a little more complicated than gasoline models, too. The normal procedure involved turning the key to the On position, before hitting a small red button to fire up the glow plugs. There was also a “fast idle” control could be activated which was linked to the accelerator pedal mechanism to help; presumably, you could just lean on the pedal for the first few minutes of running instead.  Motor Trend also noted the “heat valve” lever could be activated to restrict flow through the exhaust manifold, which the author believed to aid starting in lower temperatures. However, this may have actually been a device for boosting the output of the heater in low-speed running in cold climates, according to one forum poster.

Motor Trend also offers our best insight into the fuel economy of the engine; the diesel did not appear in the EPA’s 1978 fuel economy document, nor the 1979 edition either. The magazine managed to coax 19.1 mpg out of the diesel pickup during a mix of highway, city, and off-road driving. It contrasted this positively against more typical figures of “10-12 miles per gallon” for similar gas-powered trucks. Beyond that, the main other detail that came in for credit was the truck’s hill-climbing ability, thanks to the low-revving torque of the diesel engine.

This Dodge dealer film states “Big news for 1978: Diesel power!” In context, though, it comes up 3 minutes and 50 seconds into a four-and-a-half-minute presentation. Most contemporary materials seem to bury the diesel engine in this way. 

A rare example of the Dodge pickup with Mitsubishi diesel power.

Contrasts

It’s interesting to contrast the Mitsubishi diesel to the Oldsmobile diesel V8 that Chevy was putting in hundreds of thousands of cars and trucks. The Mitsubishi engine was more reliable, and lacking only 15 horsepower compared to the Oldsmobile unit. It was further down on torque, delivering just 169 pound-feet compared to the 220 pound-feet of the Olds. And yet, the Mitsubishi was seen as seriously underpowered and slow, while the Oldsmobile was mostly hated for its self-destructive lifestyle. At such low outputs though, the extra 15 horsepower and 51 pound-feet of torque probably made all the difference.

Fundamentally, the Mitsubishi diesel failed to connect, and sales were poor. Hardly anyone was looking for a diesel Dodge, and when they pulled the plug, nobody paid much attention. In the end, Dodge abandoned the Mitsubishi diesel after barely trying to sell it in the first place.

In the long run, it didn’t hurt the company too badly. It let Chevy ruin the reputation of diesel power for a few years, before bursting back into the market with Cummins power to great success. Today, we take high-performance diesel engines for granted, so it’s always interesting to reflect on what a massive flop they were when they first hit the pickup scene. Sometimes, patience is the key.

Image credits: Dodge, Perkins, coldwarmotors via YouTube Screenshot