The Jeep Cherokee XJ is an grand example of rock-solid American engineering. It may have been a compact unibody SUV, but it was also a bonafide, go-anywhere off-roader, especially with the right mods. There was just one thing missing—it never got a decent diesel version.
Thankfully, there’s a diehard community out there that has rectified this oversight. Enterprising swappers are pulling out old Jeep engines and dropping in diesel-burning donks for more power, more torque, and better fuel economy. They’re creating mashup vehicles from some alternate universe where American vehicles have the same breadth of engine choices as the average European hatchback.
You might look at the engine bay of an old Jeep and think there’s plenty of room for activities. That’s true. But while they can fit a mighty diesel, pulling off a swap is a real feat. I got the lowdown on what it takes—straight from the people that are involved in oiling up these beautiful old XJs.
Benz The Knee
Diesel swaps can be very appealing for a vehicle like the XJ Cherokee. They tend to offer abundant torque, as well as improved fuel economy relative to similarly-sized gas engines. That’s a particular boon when you’re driving a bulky, unaerodynamic vehicle that tends to suck down a bit of gas. [Ed Note: The true benefit is the fuel economy, as the 4.0 AMC straight-six has more torque than anyone could ever need. -DT].
“But wait!” you holler. “There was a turbodiesel XJ!” And you’d be right. Few Americans remember the 2.1-liter Renault Douvrin J8S, with its wheezy 85 horsepower and 132 pound-feet of torque. That’s because it was only sold for two short years. Europe got it a bit longer, along with a later engine from VM Motori.
Ultimately, though, the Renault engine wasn’t fitting for American tastes. Nor were the wheezy 2.5 L and 2.8 L gas engines from the model’s early years. The Cherokee’s U.S. legacy is instead intimately tied with the brawny, reliable 4.0-liter AMC inline six. Up against an engine of such pedigree, any diesel swap has to bring quite a bit of performanceto the table to justify its own existence. That is, however, very achievable with the right engine.
[Ed Note: As Lewin mentions briefly in a caption later, there was actually a 2.5-liter VM Motori Turbodiesel — the VM 425 — offered in the XJ in Europe. It’s actually a great engine, making about 114 horsepower and 205 lb-ft of torque. For a 3,600 pound Jeep XJ, that’s really not bad, and what’s more, it’s a dead-simple diesel engine with a mechanical fuel injection system.
I own a vehicle with the VM 425 — a 1994 Chrysler Voyager minivan. It weighs about the same as the XJ, and I have to say: The diesel is fantastic. It never feels slow, it gets excellent fuel economy, and it never dies.
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Well, I should be specific: It never dies in the minivan. In the XJ, the VM 425 is known to be an absolute pile. Why? Because the XJ’s cooling system was designed with smaller, less-powerful engines in mind, and as such, it only offers a single, short, wide cooling opening behind that grille. As a result, XJs tend to overheat, and when that happens to the VM 425, it cracks cylinder heads.
Yes, I said heads. This inline-four has four separate cylinder heads. And they’re not cheap to replace. -DT].
I decided to reach out to Jospeh Peterson, owner of Doomsday Diesel, for the scoop. His company specializes in producing parts for diesel swaps in all kinds of models, including the venerable XJ. We last spoke to him about diesel swaps into the Toyota fleet, and he was kind enough to share his knowledge about the Jeep side of things, too.
As far as Jeeps go, Joseph reckons the XJ Cherokee and the MJ Comanche are the most popular targets for diesel swaps. “Out of all Jeeps, I see the most demand for MJ/XJ parts,” he explains. “They spanned from the 1980’s to the early 2000’s, which means there are tons of recipients out there, and they’re also much more affordable compared to any Wrangler.”
Cheaper vehicles are often more appealing as project vehicles, but it comes down to design factors, too. “A major perk of the MJ/XJ is that no matter which engine they came with, the unibody structure is the same where the motor mounts bolt on,” Joseph says. “This allows me to create a motor mount system that works universally for all MJ/XJ’s, regardless of the engine they came with.” Beyond that, they’re also make life easy for the DIY wrencher. “The MJ/XJ is incredibly easy to work on with a hood that will open to ninety degrees and a front clip that will unbolt in under 15 minutes.”
[Ed Note: It’s worth noting that pre-1987 Jeep XJs/MJs (this was before the 4.0) have significant differences in the front clip/transmission crossmember. -DT].
They’re flexible, too. “The fact they came with an I-6 means they have long enough engine bays to accommodate almost anything,” says Joseph. “But, since they came with an optional 4.0L putting out up to 190 horsepower, owners usually want the same or more power.” Indeed, the AMC does a plenty good job of things; not just any diesel will do better. Joseph notes that this eliminates smaller, lower-powered industrial engines like the Kubota V2203 from most customer’s wishlists.
So what are people dropping in? “I have two ‘Doomsday-oriented’ options for those wanting reliable mechanical diesel power,” Joseph explains. “For the budget-minded, the Mercedes OM617 is perfect… [they’re] cheap and plentiful.” It’s an older diesel that first debuted in 1974 with mechanical injection. That makes it a simple candidate for swapping into just about anything, with minimal fuss around wiring and engine computers.
Now, it’s not a powerhouse out of the box. Stock, the OM617 it originally put out 79 horsepower and 127 pound-feet of torque. However, Mercedes eventually upped the power over the years, with turbo models pushing out to 123 horsepower later in the engine’s run.
Indeed, it’s forced induction that really lights this engine up, making it a good contender for Jeep use. “I developed a full, bolt-in kit for the OM617,” says Joseph. “Customers who don’t want to downgrade on power will absolutely want to get my turbo upgrade kit and update to the Dieselmeken 7.5mm injection pump.” He states that this setup will achieve around 40 horsepower more than a stock AMC 4.0, while offering better mileage to boot. “This is one of few swaps that can actually pay itself off if you both put on enough miles per year and find a cheap enough donor engine,” Joseph explains.
There are other options if you’re craving more, however. “For those wanting ‘all the power’, the Mercedes OM60x-series gives the best bang-for-the-buck,” Joseph says. “These newer engines can offer more valves per cylinder, smoother and quieter operation, way more power, and ten to twenty percent better fuel economy!” You can fit a wide variety of these engines, too. “The five and six cylinder variations both fit without a problem,” he says. “I offer a complete conversion kit that allows use of any OM60x engine, as well as turbo upgrades.”
Stock, these later OM60x engines put out power in anywhere from 130 to 180 hp or so. If it’s big numbers you’re shooting for, though, this is a route you’ll want to explore. Joseph notes that making a reliable 600 horsepower is possible with the OM606, for example. He notes that the Merc engines also rev relatively high for diesel engines, and they’re well matched to stock Jeep gearing. “Both the 617 and 60x are some of the highest revving production diesels of their times, governing out at over 5200 RPM!” he says. However, you’ll want to tread lighter than that if you’re looking for fuel economy. “They like to operate around 2600 RPM for the best mileage.”
There are a good number of Jeeps getting around with Doomsday Diesel parts under the hood.
The Other Germans
If you’re not a fan of the three-pointed star, or you just can’t find an engine in your area, fret not. There are other popular options. “If folks aren’t afraid of wiring, the VW TDI is a great option,” says Joseph. He notes that Whitbread Performance offers transmission adapters to pair the Volkswagen engines with the 4.0-liter transmission in the Jeep. “The 1.9L & 2.0L can easily make enough power to motivate the MJ/XJ while returning the same or slightly better mpg than the Mercedes,” he explains. “The main perk of the TDI is its tiny size and light weight.”
The TDI range is quite varied, and it’s a popular swap into a variety of models. We’ve particularly seen them as popular choices for swapping Ford Rangers thanks to their dimensions and performance. The older 1.9-liter ALH engine isn’t huge on output, with the turbodiesel four putting out 89 horsepower and 155 pound-feet of torque. However, you can step up to the 2.0-liter BHW for a much juicier 134 hp and 229 pound-feet of torque out of the box. The newer CJAA ups that even further to 140 hp and 236 pound-feet respectively. Whichever way you go, all of these engines can be further boosted for more output if you know what you’re doing.
However, if you’re truly flush with cash, you can ball out on a donk from BMW. “For those not scared of wiring or dollar signs, the N57 and M57 can put out ridiculous power while returning incredible mpg,” says Joseph.
They’re great engines if you can lay your hands on one, and unlike a lot of BMW engines, they’re considered pretty reliable. The six-cylinder M57 was built from 1998 to 2013, and put out 148 horsepower and 221 pound-feet of torque in its lowest 2.5-liter turbocharged trim. Later models went as high as 282 hp and 428 pound-feet of torque in its highest state of factory tune. The newer N57 inline-six dropped in 2008, with its lowest power version having a healthy 201 horsepower and 317 pound-feet of torque. Meanwhile, the bonkers tri-turbo version from the 2012 750d will deliver 375 horsepower and 547 pound-feet of torque. That’s plenty to motivate your off-roader, right there.
Doomsday Diesel doesn’t currently offer parts for these swaps, as Joseph notes that they’re very expensive if they can even be sourced in his area. That doesn’t mean you’re on your own though. Canadian manufacturer Turbo Diesel Conversions produces a range of transmission adapter kits for Jeeps, including the mighty M57 diesel. PMC Motorsport from Poland also manufacturers such an adapter.
I spoke to PMC Motorsport, who were happy to tell me all about the benefits of these BMW engines. So why are they so popular? “One of the most popular swaps is the M57 because of its availability, the low price of the complete engines, its durability to operate even with frequent use at high revs and yet relatively low combustion, and its compact size,” a representative told me. I’m not quite sure what they meant by “relatively low combustion,” I think something might have been lost in the language barrier. I think they mean fuel economy, which is a strong point of the M57. Owners of duly equipped BMWs report achieving highway economy approaching 40 mpg at times, which certainly ain’t bad for such a powerful engine.
It seems like in Poland, it’s not hard to come across one of BMW’s lovely diesel sixes. They told me it was “not an overly complicated swap,” noting that difficulty is very much dependent on the individual. They pointed out that some people will find the body work challenging, while others might struggle with working with the intake or electronics. Modern BMWs can be very finicky, so take those words with a grain of salt, of course.
Obviously, the choice of engine swap comes down to many factors. Often, it comes down to availability over all else. It makes sense that Europeans might find it easier to come across a BMW diesel, for example, while Americans will find VW TDIs and Merc engines more plentiful by comparison. Beyond that, it’s all about the challenge of making a given engine fit in the bay and actually run properly.
This European XJ had the 2.5-liter VM Motori diesel, but it was swapped out for the BMW M57. It looks great on a 3″ lift with 33″ tires. Plus that modern diesel purr under the hood!
How Hard Is It?
As an experienced individual in the diesel swapping world, I asked Joseph the real question. How hard is this to actually pull off? He told me the truth—none of these are a drop-in deal. There’s always work to be done. Diesel swaps may be attractive, but they’re not for the faint of wrench.
“Every single engine mentioned will present clearance challenges with the oil pan, axle, suspension, and steering,” says Joseph. “Even the VW TDI, despite being little, [it] still wants to sit where the drag link and track bar are.” The simple fact is these engines weren’t designed for the Jeep engine bay, so things tend to foul on ecah other. “The solution is typically to convert to a rear sump pan,” says Joseph, noting that he makes his own to suit the popular OM617 swap. Beyond that? “A lift is generally required to give you back some up-travel, since taller bump-stops will be needed,” he says. “Custom drag links and track bars can provide gobs of extra clearance.“
You’ll also want to take account of the gearbox. “All of my kits require a 4.0L transmission,” he says. When it comes to the smaller-engined Jeeps, they’ve got weaksauce boxes that can’t handle a real motor. “The four-cylinder transmissions were pathetically weak, dying even behind the 123 horsepower from the [stock] 2.5-liter engine,” Joseph explains. Long story short, Jeep threw the AX5 transmission in a lot of the smaller-engined models, and stuck with it for many years—even though it sucked. “While I can appreciate doing things in a budget conscious way, I don’t believe in doing things that I know will fail and cost even more money to fix versus doing it correctly the first time, hence why I don’t support the AX5.”
It’s much the same story over at PMC Motorsport. Like Doomsday Diesel, the Polish company only produces adapter kids for the AW4 automatic and AX15 manual gearboxes. It appears Turbo Diesel Conversions follows the same logic as well with its M57 adapter kits.
Joseph also advises proper research and preparation before you get into such a swap. “For the typical MJ/XJ owner wanting to diesel-swap, it’s important to first do your homework and save your money,” he says. It might be attractive to grab a cheap engine from the junkyard and just wind it up to eleven, but that’s not always a recipe for success. “Don’t go out and haphazardly buy parts with the intention to just ‘turn up the fuel screw’,” he advises. “All of the engines mentioned earlier require specialized tuning and/or part upgrades to reliably put out more power.”
If you’re putting all this effort in, it also pays to make sure you know what you’re going to get when you’re finished. Unlike some wheezy old Toyota trucks or Ford Rangers, the Jeep Cherokee could be had with a pretty solid engine from the drop. Simply put, the stock AMC 4.0 is pretty good for what it is. If that’s what you’ve got under the hood, you’re going to want to make sure what you’re dropping in is actually an upgrade.
“The biggest mistake I see with MJ/XJ swaps is people thinking the stock diesel engine will be powerful enough compared to their 4.0L, only to be severely disappointed after the swap,” Joseph says. “The happy MJ/XJ diesel owners you see are ones who planned ahead and saved up for the fueling and turbo upgrades.” That obviously adds a layer of expense. But the thing is, an engine swap is costly anyway. If you’re going to spend the money, it makes sense to do it right.
Beyond that? The final tip from Joseph is an important one—you need to get your plumbing right. “Never use barbed fittings and hose clamps for engine oil lines,” he says. If you blow one off without noticing? You’re out of luck, and your engine is toast. It’s not worth the risk. Don’t go with cheap knock-off parts, either. “Use name-brand rated hose and fittings,” he advises. “Blown hoses are the highest cause of dead engines that I’ve seen in the diesel swap world.” You don’t want to trash your new diesel rig after you’ve done all that hard work, after all!
What People Want
It’s interesting to see that there really are dedicated XJ owners out there chasing the diesel dragon. After all, it’s easy to see why someone might diesel swap an old asthmatic Toyota or Ford Ranger. In contrast, the XJ has seldom been seen as lacking for power/torque. If you bought one with a 4.0, it generally did the job. However, diesel still has its charms, and one can understand the pleasures of all that torque and that glorious fuel economy (this is key, as the XJ sucks gas) if you’re driving one of these on the regular. Plus, owning an engine swapped Jeep is just kind of special. I’d like one.
The fact is that you can build a really cool diesel XJ if that’s what you want to do. The old Jeeps are out there, the swap parts are out there, and there’s a diesel engine lurking somewhere that just wants to thrust you down the road. All you need to do is stump up the time and money to make it happen. Let me know when you do. I bet it’s rad.
Image credits: Doomsday Diesel, TDConversions.com, PMCMotorsport.com, BMW, Mercedes, VW, ReInvent The Wheel, eBay, The Green Goblin via YouTube screenshot
I got over 330whp from my 1.9 ALH TDI motivated by a larger pump and an HY35 from a Cummins.
I like diesel because it is the gearhead engine. Easy to play with things and not have to retune the ECU to constantly fight knock. Diesel’s don’t have to worry about knock. Just add fuel until you see black, then back it off a bit until it clears up. Done.
Want to run the engine without an intake? No problem. Want to run it without an exhaust hooked up? No problem. Want to delete the turbo and drive it without tuning anything? No problem. Upgrade the turbo to something bigger and want to drive it? Tune whenever you get around to it.
My favorite is being able to run boost before you need it. I retuned my TDI when I had the smaller turbo to keep it under light boost during cruise. Makes it so much more responsive compared to a gas engine that either runs boost and has no fuel economy, or has to wait for boost when needed. Compound turbo diesels can idle at 15psi all day long.
Diesel is just begging for tinkering while a gas engine with all it’s fancy O2 sensors/throttle blades/MAF sensors/etc simply *don’t* like tinkering as much.
I like diesel.
Joseph seems like a good guy.
How much worse is the fuel economy in the 4.0 for a properly done engine swap to make economical sense?
My XJ (4.0, 5 speed, no lift, stock tire size, with a roof rack) with a mostly stock (upgraded injectors) engine that is running well gets about 14 mpg in town and 18 on trips.
I have been eyeing a diesel swap for a long time for the fuel economy benefit, but mostly for a cooler running engine.
The cooling setup on XJs really isn’t great…
My XJ (4.0, 5 speed, no lift, stock tire size, with a roof rack) with a totally stock 230k mile engine which is running well gets 17-18mpg around town and 21-22mpg highway.
What are you doing wrong?
The only time I see this making sense is if something happened to your 4.0 and you need a new engine. Seems like a lot of money and time to replace what is an extremely capable motor.
Except overhauling or replacing a 4.0 is cheap and easy, much cheaper and easier than a diesel swap.
I would be FAR more inclined to build a 4.2 stroker with an AMC crank and some decent pistons. Even with adding an Edelbrock head, it would probably be less trouble.
Reading this article kept making me think back to my mom’s W123 with the turbo OM617 tuned to deliver (an estimated) 250hp and 450lb/ft of torque. It was an absolute hoot to drive when boost hit, and made it to around 400,000 miles (the odometer died at 382,000 miles) before spraying the transmission all over the road and ending up at the auto recycler.
With that said, I can’t see going through the trouble to refresh, adapt, and install an OM617 in an XJ when the 4.0L is already sufficient stock in stock form and can be modded pretty easily for a reasonably low cost.
There is a guy on the Comanche club forum who recently finished his M57 swap into his MJ. It’s wonderful, he is in Europe so those engines are plentiful there.
This is why I have the dream of finding a 2WD manual Comanche and swapping an S54 inline 6 from a BMW e46 M3 into a Comanche. The bell housing pattern for the S54 and M57 engine is the same so the adapter to the AX-15 manual should work. I’m confident the S54 would return better fuel economy than the ancient 4.0L.
Better fuel economy maybe, but not that much better. 4.0s are really not bad on efficiency and some folks report 25mpg or higher.
I don’t see how 25 mpg is remotely possible with a 4.0
The BEST tank I have ever gotten in my XJ on a 100% highway trip was 19.5
Granted, I do have a roof rack, but I checked my mileage before and after the rack and only saw about a 1 mpg drop when I added the rack. Everything else on my Jeep (that would affect mileage) is stock or stock equivalent.
Anyone claiming above 20 mpg seems suspect to me.
I get 21-22mpg highway every single time in my 94 and 95 HOs, and about 19-20mpg highway in my 89 Renix Comanche. All 5spd 4wd.
This is going 70-80mph with absolutely no special hypermiling driving, so a 4ish mpg improvement seems very possible if you slow down a little and try slightly to hypermile, especially in a 2wd XJ.
Hell, I’ve gotten like 22mpg in my F150, it better be possible to get 3mpg better than that in a way smaller and lighter XJ.
2.5 XJs were advertised with a quite optimistic 24 city/33 highway when they first came out for ’84.
I also just remembered that David averaged 17mpg highway on a long road trip in his J10, which has a 258. I would hope that an EFI 4.0 in a much smaller vehicle would be more efficient than that.
“Some Geniuses Are Turning XJ Jeep Cherokees Into The Perfect Diesel Off-Roaders By Using BMW Engines”
Taking the most reliable component of an XJ and replacing it with a modern BMW engine sounds a lot more like madness than genius.
“I think they mean fuel economy, which is a strong point of the M57. Owners of duly equipped BMWs report achieving highway economy approaching 40 mpg at times, which certainly ain’t bad for such a powerful engine.”
Really? 40 mpg highway in a brick? That’s almost double the stock 4.0. Is that with a tune that’s also going to pass any emissions regulations?
Not 40mpg highway in a BMW-swapped XJ, 40mpg highway in a stock BMW sedan. 30mpg would be a miracle in an XJ.
The M57 and follow-on diesel are actually pretty reliable (I have one in a 740LD).
As for emissions rules, sorta depends on geo and year of truck. Some states, for pre-95 vehicles, do the tail sniffer. Some are emission-exempt after 25 years. Some do tail sniffer and OBD readings. In my state, a pre-95 vehicle would be subject to the tail sniffer if it’s registered in one of the 4 counties that requires emissions; a post-95 vehicle would have to have a clear CEL and have an engine available in a vehicle the same MY or later than the car was made (IE, I can transplant an engine from a 2005 BMW into my 1999 4Runner, but I cannot transplant a 1983 Merc diesel into that same truck).
I’ve been looking at doing a TDI swap into that 4Runner, but I don’t think it’ll ever pencil out. Turbo would be nice when driving at 10,000 feet altitude, though.
I have a Mercedes W123 with the OM617A. It’s a fine engine I guess, but I couldn’t imagine spending thousands to put it into a newer Jeep. I can’t see doing this over an LS3 swap. There is a good reason people swap them into everything.
You’d do this instead of an LS3 swap because
1. An OM617 will last a lot longer, and is a lot less dependent on electronics, than an LS3.
2. Fuel economy will get better with a diesel instead of worse with a V8.
3. I know people LS swap XJs all the time, but they are CRAMMED in there and they look awful to work on.
But I think it’s just wrong to replace the mighty 4.0 with any other engine anyways, so I wouldn’t do either swap.
Here is something I didn’t know until more recently, the Jeep AW4 transmission is the same A34xx transmissions. Closest to the A340H but very similar to the A343F in my Land Cruiser. Very tough transmissions for reasonable power outputs.
Indeed and the AX-15 manual is basically an R150 that Toyota used in a ton of vehicles as well. Great transmissions that handle some abuse.
For the people questioning the point of TD swap: torque.
Also, for example in certain Nordic Yurp jurisdiction the XJ seems to be a perfect candidate for barely legal activities:
– old enough that emission requirements are marginal or easy to fulfill with a newer, ”cleaner” engine
– 4.0 base engine is large and powerful enough that the ”large” I6 or V8 diesels can be swapped in without too many administrative hiccups. Probably heavy enough as well
– it is relatively easy to boost the thing to make silly hp without too many outside clues
– available, not stupidly expensive
– dinojuice in various forms costs 7-8 usd/gallon, but the rudolf-method is way more efficient
Lifted rusted 600hp nox-deathbox, what’s not to like?
Finally, DT: thanks for explaining the technical reason why the VM lump has such a (relatively) bad reputation, even though it has been used (relatively) succesfully in demanding applications; boats, work vans etc.
One more – the 4L is HEAVY, so swapping a heavy diesel motor isn’t a major change in vehicle dynamics compared to if you were starting with a V6
The 4.0 is not that heavy. About 450hp for a long block, which is lighter than an iron small block V8 but heavier than an aluminum small block V8. It’s also significantly less than the ~600lb for the OM617.
How much better mpg are we actually talking? I can’t see this being worth the hassle unless you’re doing a lot of highway miles
It’s not uncommon for diesel swaps to improve fuel economy by 50% in some cases.
I buy that.
And I guess most of these happened here in Europe. With the gasoline costin almost 2€/l and diesel a bit less, operating thirsty gas powered car easily costs 10+k€/year. So halving that cost quite quickly comes beneficial.
I’ve got 86 RRC with 3.5V8. I’ve been pondering OM605 swap, but don’t really have usecase for it. If we drove it only, it would cost cool 12t€ on fuel only. And we only drive like 30tkm/year these days. And I calculated that conservatively with 20l/100km, I think it really drinks around 25l/100km.
I put a GM 6.2 diesel in a Grand Cherokee and would see 25 +/- mpg regularly. That was with a 700R4 trans with OD and 3.07 gears.
I find it funny that Doomsday is showing pictures of an OM606 on the page for the OM617 swap.
I was originally going to give Lewin shit, until I clicked through and saw he literally pulled the images from their product page.
I have seen multiple 4BT conversions, one or two TDI VW’s, but those were in a Toyota Truggy and A Samurai Crawler. I cannot really say I have ever seen a Merc Diesel in a Jeep. I suppose if it works reliably, it would be fine, but old Mercs, especially hopped up turbo versions seem less likely to be more reliable in the end. I also recall plenty of 70’s diesel car basically not rusting because of the massive amounts of oil they leaked all over the undercarriage.
I was thinking about the 4BT all the way through the article. I hear they’re heavy though.
4bts are heavy, about 300lb more than the stock 4.0. More importantly, they’re wide. I suspect this is the reason I have never seen a 4bt XJ.
A 4.0 barely fits between the frame rails of an XJ, and 6bt/4bt blocks are really really wide for an inline engine. I haven’t measured, but I think it’s literally wider than the frame rails.
A 4bt also makes only 105hp, and barely more torque than a 4.0.
I kind of agree with David, had both an XJ and WJ with the 4.0L. These engines are NOT short on torque and are stout, reliable units. Both of mine were at 190,000 plus miles with no more than plugs and oil. I can understand the fuel economy benefits (I was at 16-17 mpg overall on both) but not at that cost.
16-17 from a box on wheels is pretty decent. I see plenty of the HO 4.0’s with auto’s getting far less. the 5 speed with OD however might be close to 16 in a wrangler.
Maybe I was at 14 – been a lot of years.
I get ~18 city, 21 highway in my 5spd HO XJs. I have heard of some folks getting as high as 25.
I think the auto really destroys the fuel economy of these cars.
Yeah I get 14-18 in my Renix MJ depending on the sort of driving I’m doing. 267k miles and it runs perfectly after I did all the recommended tuneups. I like the 4.0L, don’t really see much benefit in swapping it out.
Everyone take a shot. 😛
If you’re of legal drinking age, of course.
Hah! We should just brand it. It’s basically a series now.
Area Man agrees!
XJs are getting so hard to find in my area as the cash-for-clunkers thing put so many of them in the junkyard, and rust is taking the rest. 23+ years of road salt is hard to survive.
Yep, I bought a well used ’89 XJ in 2001 for 1k. Cleaned the interior and patched it up, resprayed in dad’s driveway. Drove as winter beater and DGAF car. Hit a patch of ice and a guardrail, grafted on an ’88 Wagoneer front clip and drove for another year. Got 1k as a trade on a 1999 WJ in late 2004.
In the US, I still don’t see why anyone would diesel swap a Jeep when the AMC 4.0L is dirt cheap, has lots of aftermarket support (including very spicy stroker and forced induction options), and is bulletproof. Yes, gas mileage isn’t great, but if you’re running 37″ tires on stock gearing, a diesel swap isn’t going to magically fix that.
Diesel averages $0.40/gal more expensive than regular gasoline across the US, so unless you’re making biodiesel at home, you’re really going to have put on the miles before the diesel milage argument makes sense (again, focusing on the US here, the calculus may be entirely different in other parts of the globe).
Don’t get me wrong, a Mercedes diesel looks cool in there, I just don’t see the practical application when the venerable AMC 4.0L came in these from the factory.
I agree. Places where diesel is the go-to fuel the swap may be more cost effective. If I had an XJ I would think that rebuilding a worn out 4.0 would be the best choice.
Most of the time it is to reduce electronic issues. Specifically Nebraska river Runners. For some reason the diesels with snorkels tend to run under water better.
You can eliminate 90% of the wires going into an xj engine bay if you don’t mind lights on the dash, which I can’t imagine those folks do.
Yeah, I was wondering this. Diesel is typically a $1 more per gallon where I live. The 16 mpg average o get in my MJ with the 4.0L is fine. I make up for it by driving my Austin Healey Sprite which gets like 27mpg.
It’s cheaper or equal in UT and CO the last few months.