I have an '87 Jeep Cherokee 4x4 with the I6 gas engine and AW4 automatic. The engine has over 350,000 miles and I was planning on rebuilding it as a stroker before I build it up for off-roading. After reading around on the net, I found that it's not recommended to tow heavy loads with a typical Jeep. Me and my wife plan on buying a Cabin Cruiser boat in the 21 to 27 foot range in the near future and I would like to be able to tow it with my Jeep rather than having yet another vehicle just to tow the boat, plus I would like to have some fun with the Jeep wherever we take the boat (probably mostly around Lake Michigan and Lake Barkley in Western Kentucky). So I figure I could take the money I was going to spend on my stroker and transmission rebuild and put it into a diesel swap. I already have a Dana 44 front and Dana 60 rear full-float pulled from a '79 F-250 to put into the Jeep, so that's taken care of (I could use some help on choosing the gear ratio though, they're currently 4.10). Basically what I'm looking for is either a straight six or V8 diesel that'll fit in my Jeep along with a matching transmission and t-case that can handle off-road abuse, tow a 27-foot Cabin Cruiser, and get decent highway mpg if possible (I currently get 15 mpg so anything higher would be great). I've done some research and found that the I6 engine that's currently in the Jeep weighs in at about 515 lbs and that a recommend V8 gas engine swap is the GM small block V8 (LS1) so anything close to those specs would be great. I'm new to diesels so any help would be appreciated. I do all of my maintenance and repair work on my vehicles so I view myself as mechanically literate but I've never owned or worked on a diesel, I do understand the basic operating principals though. I would prefer an automatic transmission but my daily driver is a manual so I know how to drive one and would be open to putting one in the Jeep, I would just prefer an auto for off-roading. Also, the front axle's differential is on the drivers side, something to keep in mind when recommending engine, tranny, t-case setups.

Thank you for all your help and/or comments in advance

 

https://www.dieselbombers.com/diesel...des-om617.html start here with this site and there are others to check out to just put jeep engine diesel swaps in the search at the top of the page on the right

 

Let me answer you some questions.

I do have the stock 2.5L TD built in '99.Torque is the same as the 4.0, only shifted 2000rpm lower.
When I go on a step hill with ease- the 4.0 already has to hit the pedal.

Towing?:
Towing is limited in europe due to safety regulations to 4630kg that is 10200lbs.
I only towed a boat so far with around 8000lbsand some trailers loaded with wood. That engine is built for towing! You don't recognize the trailer
during normal driving.
It still uses the AX15 manual tranny-no problem at all.

mileage:
25mpg with ease, 28mpg when you go like grandma(with 225/75 R15 tires and a 3.73 gearing)
but- if you hit the pedal once- you will be in the low twenties or less....
If you think about a Diesel conversion, go for it- if the towing weight is within your weight limit!

 

My vote is to go with the OM617 Benz engine. A 4BT would be cool ,but would probably cost more and you may have to beef up the front end. The OM617 would not weigh the front end down too much. Just my .02


John

 

yeah, the OM617 looks very promising, I'm just worried about it's ability to tow and the ability of it's transmission to handle towing also. The 4BT's torque is insane (355 lb-ft ). It does way about 230 lbs more than the 4.0 I6 in the jeep though. Could that weight be compensated with stiffer springs in the front, or would it cause stability issues on and off the road?

 

4BT > OM617

 

I really like my OM617 in my cherokee, but I wouldn't even try to tow such a large boat with it. I wouldn't feel comfortable towing anything that large with a cherokee no matter what motor it has. The benz motor is a nice choice for the cherokee because of the uni-body. The 4bt needs a stronger platform imo.

 

To tow anything that big you need gobs of torque - like what is available from the 4BT. However, like FTE said, even with the torque and HP to pull it, a Cherokee would be a poor choice - at 3500 lbs curb weight they're just too light and don't have sufficient braking power for towing that big of a load.

The extra 230 lbs of the 4BT is no problem - a heavy duty bumper with a winch can weigh that much and people put them on Cherokees with no problem all the time. For a uni-framed vehicle like a Cherokee, you need to limit the torque somewhat or seriously beef up the front uni-frame. At 355 ft/lbs torque a 4BT is going to tweak and twist the front end more than it was designed to handle. You can box the uniframe with 1/8" plate steel to stiffen it up and get it to hold up - IF you have the metalworking skills and tools (plasma cutter, mig welder, grinders, drills, etc.)

For a 21-27 ft boat, what you need to do is trade the Jeep in on a diesel Excursion or Suburban. Something with enough weight, towing capacity, AND power to do the job.

IMO, If you're stuck on the idea of a Jeep and a 4BT, find an early to mid-80's Wagoneer with a blown up 360 V8 and swap a 4BT (or even a 6BT) into it. The old Waggys have a full frame and are robust enough to handle the torque and they're a heavier vehicle with bigger brakes more suited to towing the kind of load you're looking at.

 

You're jeep cherokee is already old and it would be better if you buy something new. But if you really need to replace some of your jeep cherokee parts, then you go here > jeep cherokee parts list for all models.