Diesel YJ Flat Bed Truck

[dieseljeep]

This project is a bit far off, but I got a free YJ that has been wrecked. It has 2.5L with manual transmission and the NP231 was broken in half during the wreck. A motor mount is broken, bunch of little stuff has been broken and the hard top was broken, including some rear damage.

My plan is to save the frame and stretch it and save the front half of the tub and use the rear half to make a trailer.

I want to do a diesel swap, but I'm not sure which one. I have a TJ with a R2.8 Cummins and I really like that engine, but I kind of want to go 4BT or Kubota or TDI or something and I want to probably run a 3/4 ton manual transmission, a doubler t-case with a Dana 300 (4:1)/NP231 (I'll have a spare one once I swap mine out on my TJ) and I'm not sure for the rear axle, but I think it was damaged.

I am pretty much stealing this guy's build on a R2.8 forum I have posted on looking for specific info on that engine.

I may not go snorkel (it's obviously not a TJ), and I like a more minimal bumper.

This build is not my focus, but any comments and considerations are welcome. I just have tractors I've got to get fixed and my TJ needs gearing in the rear and t-case and suspension work and whatever else I decide to add eventually. The TJ is my DD, but when it is done, and from some mods I want to do on my truck, then I want to get into this.

I may start on the trailer first. So any suggestions, let me know.

 

[Chris]

Very cool! I've been thinking a lot about buying a YJ since they are so cheap and then swapping in an older Chevy 350. With carbs it would be an easy swap, and my guess is I can do it on the cheap.

I'd love to swap in an R2.8, but those things are just so expensive that I don't want to get in over my head.

 

[dieseljeep]

Just depends what you want. I would never go back to gas after having diesel 4x4s and equipment and for the price of a brand new, rare in US diesel engine, the R2.8 has a lot to offer, even if it's not the best diesel ever. It is small and cast iron on cast iron, with sleeved cylinders, so it's not bad, but chain timing and weak bottom end and higher cooling requirements, is kinda unfortunate.

All of those engines I've mentioned previously, once rebuilt from a reputable builder will have you near the R2.8 price and the R2.8 is almost as easy to install as the 4BT, wiring-wise. The Kubota is easy in theory, but you gotta change up the piping and turbo stuff and tune it, just to make it more streetable. 4BT really needs to be tuned once it's ready for being fun on road and off and those blocks are going for like $4k used and often need to be rebuilt. Also the 4BT needs lifted and the whole front end redesigned to handle the weight. However I must admit that I really want a 4BT or similar engine if I can get one. I did have a source for one for like $1,500, but I'm sure it's gone by now. I kinda think that with good motor mounts and body mounts and springs, the YJ could handle the 4BT pretty well. There's almost no penalty in MPG for the added displacement either, in fact having more will give much much better results than too little.

As far as gas engines go. V8 is obvious, but they don't really shine until they're revved up and when I'm off road I don't want to be revved up, but I'm not going for the, "I think I can jump it", type experience. I like to go through obstacles very slowly and spin as little as possible. Not to mention that they guzzle the gas so you're always thinking of refueling and gas cans. It's the worst fuel to deal with as well.

That's what I've ran into before, when I need to refill some gas cans. They literally won't hold more than a gallon or so in that state and you gotta wait until it gets really warm to bloat the cans again. Gas destroys the Nato fuel can (these plastic cans are so thick they barely budge) gaskets as well (pressure not a material issue per se), so you end up using stale gas if you don't spill it everywhere and in a carb injection system, you may have trouble starting up with stale gas. We don't have that problem in our diesel tractors, even if the fuel is growing algae.

I've filled up gas cans in the winter and then on a warm day and like an idiot, stood over top the can while removing the top and been sprayed in the face with gasoline. Though hilarious, it does suck while your nostrils are filled with fumes and your eyes are burning.

Now would I keep a gas engine in a vehicle, Absolutely. They are fine, but there's no way I'm going through the effort to swap one into a vehicle that wasn't designed for that engine. It's a pita in my experience, so if I'm gonna do it, it's gonna be a diesel. The diesel WILL NOT SAVE YOU MONEY either. It's just the low end torque, fuel economy, engine life and reliability, fuel characteristics, non-flammable fuel, etc. And it's not really the fuel economy, rather the extended range. But off-road they're basically better in almost all scenarios of gas counterparts. There's a lot fewer issues that can get you off the trail and to a trailhead as well. Busted radiator, non-issue. Blown head, cracked block, messed up injection, air system, exhaust, sensors, etc. You might limp out but none of those matter which makes buying used such a problem, because those don't matter until you've tested a loaded engine.

There's too many great engines already in many great 4x4s to go through that effort and then you can get all the other stuff like easy to find parts and stuff you get for gas engines.

If it's a specialty situation then I really would rather tow a gas powered 4x4 on a long trip with a diesel powered truck.

With this YJ starting off with a 2.5L, it didn't really start life with anything other than an engine swap in its future. If you go with V8 or whatever, I can certainly understand, but to me I'd find a 4.0 or go with another vehicle all together if I'm staying with gas. Part of me thinks the Grand Cherokees are almost better choices, just because the small engine was the 4.0 and the 5.2 or larger is very handy. Sucks that wasn't the Wrangler option. It also sucks the Grand Cherokees were unibody, but those were the times.

I'm not sure I could argue with a 5.2L YJ from the factory. I'd just buy more gas cans and stretch the frame to swap in a bigger fuel tank.

 

[Chris]

I'll be honest, my only issue with the 4BT (aside from how much it weighs) is how loud it is. I took a ride in a TJ with a 4BT swap, and with the top and doors off sitting at a stop light, it practically rattled my fillings out and I was sick of it after 10 minutes.

I'd like the best of both worlds. A quieter diesel (like the new ones), but also one without all the emission bullshit that eventually fails. I'd also like an older diesel that is easier to work on with less stuff too break.

There's so many diesels out there that it's hard to pick which one would be right.

I'm with you on swapping in an engine, but do you think a 350 with carbs would really take that much effort to put in a YJ? Novak and AA sell all the adapters, and the wiring would be minimal at best.

I'll have to look into it more, but it seems like it could be way easier than putting let's say a Hemi or a newer LS engine into a TJ. Maybe I'm wrong.

 

[dieseljeep]

I don't think adding a 350 would be hard in a YJ, TJ, or CJ, it's just that all of those projects require so many little brackets and additions that when you're "finished", the end results are little things that will break more often and fewer people can help you. And I see it as, I can either find something from the factory that's pretty much exactly what I want or in the case of diesel, it's not really there, unless you want to drop $50k and now the emissions stuff will have to be removed for probably another $2k. Not to mention the cost of taxes and insurance. But you can probably find a JK with with the pentastar in it with low miles and it'll be 80% of what you want with very little work. I think I kinda like the JL a bit more than the JK, but I've never really messed with a JL. Still a Rubicon used for a JK isn't gonna be cheap and the JLs are so new, they aren't gonna be cheap. And there's other pretty good vehicles out there that Toyota makes that are pretty darn reliable and capable for a similar price point.

The 350 has other advantages as well, since you can get so many parts and accessories that are from some OEM and just use the best and most common that you can get almost anywhere. I still think it's all a headache, until you've done a few installs and probably a few installs of the same engine and every single time you'll probably do something slightly different. I would guess that even after 100 swaps, you'd still be making changes. The other issue I have is that I just don't like Carburetors. I just don't have luck with them. Seems like I'm always screwing up the choke or something and flooding the engine, or some part gets the tiniest particle of dust, or the ethanol in the fuel destroyed some line or something (had it eat a hole in a steel gas tank). Or a fuel shut-off solenoid malfunctions, something pulls a spark plug wire or something happens to the distributor, etc. I've even rebuilt carbs and distributors and immediately had faulty parts that wore out super quick. I've spent so many wasted hours on this stuff, that I really don't care for it.

Yeah I've heard the 4BTs are crazy loud. My 5.9 Cummins in my truck is, for one an inline 6, which is probably better balanced and then surrounded by sound insulation, but it's still kinda loud when you're outside. The 4 BT is just so tough, once it's setup. If something isn't quite right, they're pretty expensive from what I can tell to fix if you don't do it yourself and done know all the nuances. That's why I tend to want to get a new engine, swap it in and then get hundreds of thousands of miles on it and when it's done, pull it out and take it somewhere to be fixed properly and do it all over again. 4bts aren't the 6BTs though, which are just naturally a bit easier on everything, but obviously they are too big for a Jeep. Well unless it's the size of a Gladiator. I would suspect with some work, the vibrations could be dealt with. Sound IMO is harder on these Jeeps, because they're already so small and you just don't have great places for sound insulation I would think.

Kubota would certainly be very cool on paper, but I'd want one with a bit more displacement, because I would imagine that once make 2x or more HP than it was originally designed for that maybe there's be engine life issues, not to mention, you don't really know if the engine was worn out before you got it. I've been watching Grant's build closely, but I'd love to do a build with one of these if time and money, well money were no object.

VW TDI is high on my list. If a guy at work will finish a couple swaps before I get around to working on this, this may be my path, because part of the issues are integrating the electrical stuff. If my buddy figures this out, then I'm not too worried. Displacement is a bit of an issue though. I really want something that can have 300+ ft lbs, partly just because I want the gearing of a 3/4 ton manual transmission, but those are so heavy and bulky for no reason on a smaller engine and there just aren't many options that are easy. There's a way to get some gearing from a Toyota type transmission and build an AX-15, but I've yet to see exactly how to do this. I really want a 5 or higher 1st gear with a diesel motor (maybe all motors). 5.15 is somehow possible, but I don't know what parts to get nor have I pulled a manual apart and swapped out countershafts, gearing, input shafts, output shafts, bellhousings, etc. Using an AX-15 instead of a 3/4 ton transmission could save 100 lbs and some drivetrain length, which for an entire build adds up.

And then there's the R2.8 and the size and the ease of install makes a fair amount of sense. The emissions equipment it has is almost a wink and nod away from removal out of the crate, though that's probably $1,500 worth of waste just to get that engine to your door. EGR is an absolute negative for the build, and the DOC imo is a risk to use off-road, but honestly I think all catalytic converters are risky off road, though I'll still run them. I've also seen them light up a field and melt a vehicle down too.

But yeah small block is certainly a good option for a swap, but it's harder for me to justify since there's stuff out there kind of similar and I just don't go out passing people (for one I can't do that anymore). I like going slower and I like exploring more than going fast and tear through obstacles. But yeah that's probably not conducive with a 4BT unless I can find some really good sound deadening insulation.

 

[Chris]

I think my other issue with the 4BT is weight. They are heavy as hell. That Kubota that Grant has going, I wonder if that's going to be enough to really keep that TJ at highway speeds?

Not that the TJ is a great highway vehicle to begin with, but I'd like to know I could at least keep up with highway speeds if I need to.

Having owned a hell of a nice JK Rubicon, I ended up getting rid of it because it just wasn't me. It drove like a dream, was quiet as hell, and had more power than you'd need in a Jeep. However, it was inherently complicated, which must mean the JL is even worse. Not that that doesn't have it's perks, but if you like working on your own vehicles, the JK and JL are a mistake in every sense of the word.

I know what you mean about the carbs, they can be finicky. However, I guess if it was just a vehicle for cruising, it wouldn't be so bad. I'm not sure how much I'd trust a carb to go off the beaten path in though.

 

[dieseljeep]

Once I re-gear, I think my TJ will be very nice on the highway for a Jeep. It's not bad, but many those 3.07s just aren't enough for mud tires, roof, rack, winch, etc. Before the rack you had to look down more often to make sure you hadn't drifted up to 80+mph. I wasn't even running a front sway bar then either, so it was incredibly sloppy with turns, but that torque will fool you. You don't speed up quickly with low hp/high torque, but you tend to slowly drift to higher speeds. I'm also waiting to put on my black magic brake stuff when I swap in the 3.73 axles with ARB lockers for the TJ. I think that's really gonna make that drive really well on the road after that. Off-road, has got to wait until I pick up an Atlas. It's way too fast off-road. At a minimum it needs to be half the speed it currently can do and I think 3.73 and 5:1 will make it good enough. If I can figure out how to get the AX-15 5.15 first gear, then that's gonna happen. The gearing looks great for a 5.15 AX-15. Should be able to take off in second without any throttle and the 5.15 will be very handy with a trailer or on gravel/rough roads. And a 96 crawl ratio gives me a bit of a smile.

I think Grant will end up getting the Kubota to where it'll run the highway pretty well, but I'm not so sure it won't require a bit of black smoke at times. I think he'll likely end up with a slightly bigger turbo and enough fuel, which I would guess isn't injected as finely as common rail, and before the turbo spools up, I'm guessing he'll be a bit sooty. Hopefully my gut feeling is wrong, because I bet he wants a pretty clean burning engine.

That's why I would want as much displacement as possible. If I were looking for a Kubota, I'd really want to look for the biggest piston version and then try and find a way to stroke it. If one could get close to 3L and then stroke it to around 3.2L, I think one could get a nice reliable 180ish hp/360ish ft lbs. However that's gonna put you in a price beyond the R2.8 and if you did that work to a R2.8, which does seem to be out there as an option, you'd be reliably around 225hp/450 ft lbs, which would be exciting in a Jeep, though excessive.

I'm with you on the new Jeep stuff. It feels like Legos or something to me and there's so much stuff that has no benefit the way it was done electronically vs a simpler way. I'd much rather have a properly setup TJ, YJ, or CJ. Those just look so much better and have a timeless look and feel. The new stuff mostly just blends into the crowd, but I think they do a better job with the sound and how loud all the earlier vehicles were. The sound insulation is frustrating to me, in that I would really like to make it super quiet, but getting there requires me to do stuff I don't like doing to a vehicle. Also once the doors or top come off, you're incredibly loud. My method has just been to wear hearing protection. I run some Bluetooth Rugged Radios stuff and can plug into radios and stuff that makes it much easier to communicate, though I'm still working through bugs in my setup.

The wife kind of wants one of the 4-door Jeeps, but for what it is, I lean toward either an FJ, TRD-Pro Tacoma extended cab, Chevy ZR2 with Duramax extended cab (I almost bought this, but instead ordered a R2.8 and Axis kit), or maybe a short bed 3/4 ton diesel with some type of extended cab.

I do wish I had the time and money to thoroughly build a Jeep exactly how I wanted it, even down to the wiring and removal of pretty much all relays in the system. I wonder if maybe a tub could be made integrating sound deadening stuff with fiberglass/composite mats to bring down tub weight, reduce interior noise, and heat transfer kind of thing. Unfortunately that would just be an incredibly slow and expensive process. I did some work in college with a bunch of people and it was incredibly tedious to design and build something that still needed major refinements.

 

[Chris]

I think if I were going to buy a 4-door vehicle similar to a Jeep, I would just get the Chevy ZR2 at that point. Being a truck it's more practical.

I still look at Wranglers as being a recreational vehicle, and one that should be as simple as possible. My JK felt like an SUV. Not that that's a bad thing. It was quiet, quick, and extremely well mannered compared to the TJ. However, it no longer felt like a Jeep to me. There's so many JKs and JLs on the street that like you said, they blend in.

I want the Wrangler to be something I feel comfortable wrenching on, which is why I am now pretty much dead set on CJ, YJ, and TJs.

Another interesting diesel swap on the YJ Forum is that CRD engine from the Liberty. Did you see that one? He's done a damn good job putting that thing together. I've never driven a CRD Liberty, so I'm not sure how that will feel in a Wrangler, but it's a cool swap nonetheless.

When it comes to diesel swaps though, I think the R2.8 is probably the best bet. It's expensive, but like you said, if you went the 3.2 Kubota route, you'd probably end up costing the same or more, at which point it doesn't make any sense.

The real question with the R2.8 is can you easily get parts for it if you needed to?

 

[dieseljeep]

I've seen Mike's build on the TJ forum, which is super cool. Haven't seen the YJ, but though an insanely cool build, it's just too much for me I think. I'd be trying to design 1,000 brackets and move on to too many rabbit holes in a project that big.

I do think R2.8 parts will be available, to some degree, just because it's everywhere else in OEM vehicles besides the US due to emissions laws. Cummins does have some trouble with some part numbers, but they supply a variety of rare engines in general so they should be able to get some parts.

Aftermarket for the 2.8 is probably better than I expected, but still not as plentiful as something obviously abundant like a small block 350 or something.

I feel like CJs, YJs, and TJs are more like UTVs, eventhough I think they're the most true form of SUV. Most "SUVs" are just cars with a lift kit or in the bigger varieties, just a truck with a dumb body kit. The convertible nature certainly puts Jeep apart, but you gotta look a bit to tell the difference between the new Wranglers, Liberties, Cherokees, etc. I like trucks a lot too and this journey to make everything feel like a car annoys me with trucks too. I just need a basic seat, good mirrors and AC would be a bonus. I do like 4 doors on the trucks though. Being able to have passengers really expands the limits of a truck with a good backseat.

 

[Chris]

I always concerned a true "SUV" to have a body-on-frame. So basically a truck with a different body. The 4Runner and Tacoma for instance show how a truck and an SUV should be. Mostly the same frame, but different bodies.

Unibody vehicles should just all be called crossovers in my mind.

I've got a 2003 Tacoma TRD double cab, and I love that thing.

Here's a picture of it:

I like the earlier Tacomas because they are small enough to still go places, but still a truck.

You'd be surprised how big the back seats are in that too. I have no issue fitting both kids car seats in it.

 

[dieseljeep]

I didn't realize Toyota made the Tacoma's bigger. I definitely would like a small 4 door truck. I can't understand why someone would want a half ton or sub half ton the size of a 3/4 ton.

The unibody and everything is very limiting too, but Jeep probably understands that 99% of the new models sold will very rarely be used off road. They make them fairly capable in OEM form though.

 

[Chris]

Oh yeah, look at the second generation Tacoma starting in 2005. It's massive compared to the first gen Tacomas. Side-by-side it becomes apparently obvious.

And that's my issue with them. For the size of the newer Tacomas, I'd rather just have a full size truck which would be way more capable anyways.

I agree with what you're saying about the unibody. It's definitely more efficient, and unless you're towing or doing some real off-roading, the unibody is the path forward for them, just like IFS.

Just be careful with unibodies. I've flexed them off-road, and the entire body will contort causing things to bend, and your doors will never shut the same again.

 

[dieseljeep]

Yeah I always look at half tons and my 3/4 ton sucks in a few ways but dominates most half tons. If you're easy on the throttle low 20s is pretty easy to get and it's so much nicer towing. I tow stuff that could easily be towed by a half ton but those engines really drop in MPG and those engines are so wound up, where my engine and brakes aren't affected at all.

Also when I'm going downhill I get a lot more naturally engine braking as well. And at work we noticed the half tons really dropped off with their hauling capability. Just a few years ago we used a half ton like a 1 ton. Now we don't get anything smaller than a 1 ton and we go through transmissions and the engines, though rated higher aren't doing what the large displacement engines used to do.

Reluctantly we use the diesels because of how they haul, but they're in the shop a lot due to emissions equipment. My pre-emissions diesel is a great engine and transmission and same axle as the new ones. I feel like an old man hating on all the new stuff, but early 2000s seems like there pinnacle of vehicles in many aspects.

 

[Chris]

Reluctantly we use the diesels because of how they haul, but they're in the shop a lot due to emissions equipment. My pre-emissions diesel is a great engine and transmission and same axle as the new ones. I feel like an old man hating on all the new stuff, but early 2000s seems like there pinnacle of vehicles in many aspects.

I was thinking the same thing as well. After 2006 (which is coincidentally the last year of the TJ) is when things started getting really complicated.

I too sound like a curmudgeon with how I hate on new stuff, but really it's just because I hate how they've sort of locked us out of doing most of the work to them ourselves. They've made newer vehicles inherently complicated (albeit way more efficient) for the DIY mechanic.

Hell, look at this article I saw the other day on the new Ford F150 interior:

Spied: 2021 Ford F-150 gets a big touchscreen, digital instrument cluster

The next F-150 is joining the big screen club, and based on these spy photos, it looks like its cabin goes even further into the digital realm than the competition.

www.autoweek.com

Basically your entire dashboard is a huge screen. Imagine what happens when that thing has an electronic problem

I always thought of trucks particularly as being rugged and tough. Now it just seems that they're the opposite.

Don't get me wrong, I'm sure that thing will drive so smooth you won't even know it's a truck, get good MPGs, and be way more efficient than a 90s F150 (or similar), but it's just not the same in my mind.

 

[dieseljeep]

Ok. I've been kind of on the lookout for a VW Jetta or something with a TDI in it. One issue I have with this route, is that I do want this to have some pretty good low end torque and unless I go with something like a compound turbo setup, I'm not sure of the best way to go about this other than multi speed transfer case and essentially using a lot of gearing. I have thought maybe on running 33s and maybe 4.56 gears, AX-15 and doubler t-case. Along with trying to push maybe 160 hp from the TDI, I would imagine I'd be able to drive around pretty comfortably.

On the other hand....

Well a buddy has the drivetrain of a mid-90s 1 ton Ford with the 7.3L diesel (I'm not sure if this is the powerstroke or international my dad has an international and it's a good truck). If I could even make this fit which I don't know the dimensions, I'll have to actually turn the Jeep into a 1 ton to handle all of this weight, but I'd get really nice torque in probably a 5,500 lb vehicle. At this point, I'd probably buy a 4 door YJ tub (or figure out how to make one) and just commit to the size of something like a Gladiator, but flat bed and 1 ton axles and suspension.

 

[ranchoazulcolstrip@gmail.]

I was thinking the same thing as well. After 2006 (which is coincidentally the last year of the TJ) is when things started getting really complicated.

I too sound like a curmudgeon with how I hate on new stuff, but really it's just because I hate how they've sort of locked us out of doing most of the work to them ourselves. They've made newer vehicles inherently complicated (albeit way more efficient) for the DIY mechanic.

Hell, look at this article I saw the other day on the new Ford F150 interior:

Spied: 2021 Ford F-150 gets a big touchscreen, digital instrument cluster

The next F-150 is joining the big screen club, and based on these spy photos, it looks like its cabin goes even further into the digital realm than the competition.

www.autoweek.com

Basically your entire dashboard is a huge screen. Imagine what happens when that thing has an electronic problem

I always thought of trucks particularly as being rugged and tough. Now it just seems that they're the opposite.

Don't get me wrong, I'm sure that thing will drive so smooth you won't even know it's a truck, get good MPGs, and be way more efficient than a 90s F150 (or similar), but it's just not the same in my mind.

We have a 16 ecodiesel and it does everything I need (pulls a 75 20' camper and my flatbed). I also have an 03 5.9 HO dually. At 67 MPH, I'm getting 22 mpg unloaded.
The 16 is on its 4th EGR cooler/valve setup! <80k miles! I also have a 92 YJ Renegade with all original parts (including top) which is really starting to have gaps! I love everything about it except the open diffs. When things go bad, LF & RR will get you stuck everytime!

 

[dieseljeep]

I always concerned a true "SUV" to have a body-on-frame. So basically a truck with a different body. The 4Runner and Tacoma for instance show how a truck and an SUV should be. Mostly the same frame, but different bodies.

Unibody vehicles should just all be called crossovers in my mind.

I've got a 2003 Tacoma TRD double cab, and I love that thing.

Here's a picture of it:

View attachment 115538

I like the earlier Tacomas because they are small enough to still go places, but still a truck.

You'd be surprised how big the back seats are in that too. I have no issue fitting both kids car seats in it.

My wife just ended up getting a 2014 Toyota Tacoma TRD Pro Baja Edition double cab. It's not too large either. I almost bought an imported mid 90's Hilux, but she didn't want it. I'm thinking I'll convert the 2014 to a Hilux when the engine dies.

 

[dieseljeep]

We have a 16 ecodiesel and it does everything I need (pulls a 75 20' camper and my flatbed). I also have an 03 5.9 HO dually. At 67 MPH, I'm getting 22 mpg unloaded.
The 16 is on its 4th EGR cooler/valve setup! <80k miles! I also have a 92 YJ Renegade with all original parts (including top) which is really starting to have gaps! I love everything about it except the open diffs. When things go bad, LF & RR will get you stuck everytime!

I had a buddy with the EcoDiesel and I really would like one of those, but they're so pricey if you can find one. I should I bought my buddies, but I wanted the bigger backseat than he got.

The EPA stuff on the newer stuff worries me A LOT. It's a PITA at work. The EPA stuff is garbage and kills the engine life WAY too early.