86 MJ flatbed 2.5

[jeeper_chiefb]

I picked up this truck for around-town parts runs and to keep my Ram 2500 parked. I've never seen a Comanche with a flatbed and I'm hoping to use the bed for axles, tires and such for my jeep projects.

 

TBI 2.5L, AX-5.  At some point in life it was converted 2wd to 4wd with a cable-actuated Dana30 and a 207 t case. It ran like crap, barely idles, power steering leaks, valve cover leaks, but it was only 1500$ on FB marketplace.
 

[jeeper_chiefb]

I began engine troubleshooting by installing a new fuel filter and fuel pump. That worked for one short drive.  I replaced the Idle Control Valve, as well as most of the wiring to clean grounds. Another short drive and it died, no start. I kept throwing parts at it such as a crankshaft position sensor and ignition module, and it drove again.... about 4 miles. 

Finally I took it to TimBukThree Automotive in Westcliffe, CO who works on CJs, YJs, XJs and MJs regularly. He found the ECU was failing and replaced it. It runs great now.
 

 

[eaglescout526]

ECU failing huh. That’s a new one. 

[jeeper_chiefb]

I've put just over 2k miles on it since replacement and it's been great.

[jeeper_chiefb]

The 29 year old interior definitely needs some help to improve the comfort.  The sagging bench seat was the biggest problem.  I pulled it out and vacuum years of grub from the floor.

 

Also put in a new starter.

 

 

 

[89 MJ]

I hope you pulled up the vinyl flooring too to check out the condition of the floors. I don't think I've ever seen a truck with the vinyl floor that didn't need floor work. Looks like a pretty good truck though. 

 

Also, what makes you think that it was two wheel drive originally? I believe that 86s still had the NP207 and the cable actuator on the front axle could have just been to delete the factory CAD stuff. 

[GonzoTheGreat]

21 hours ago, eaglescout526 said:

ECU failing huh. That’s a new one. 

I lost a remix ECU once after doing some welding on the rear bumper. Battery was disconnected, but ECU was not. I learned the hard way to unplug the ECU next time. I bet someone did some welding on the flatbed while it was attached to the vehicle. 

 

The Comanche looks great! What a good deal! I bet it will make a great run-around-town truck. 

[jeeper_chiefb]

On 6/18/2025 at 9:54 AM, 89 MJ said:

I hope you pulled up the vinyl flooring too to check out the condition of the floors. I don't think I've ever seen a truck with the vinyl floor that didn't need floor work. Looks like a pretty good truck though. 

 

Also, what makes you think that it was two wheel drive originally? I believe that 86s still had the NP207 and the cable actuator on the front axle could have just been to delete the factory CAD stuff. 

Yes, the drivers floor pan is rotted out and I've ordered a replacement floor.  On the to do list to weld it in.

 

The previous owner told me it had been converted from 2wd, but he didn't say he did it.  A VIN check confirms it was originally a 2wd truck.  I plan to replace the front axle and transfer case with upgrades.

[jeeper_chiefb]

2 hours ago, GonzoTheGreat said:

I lost a remix ECU once after doing some welding on the rear bumper. Battery was disconnected, but ECU was not. I learned the hard way to unplug the ECU next time. I bet someone did some welding on the flatbed while it was attached to the vehicle. 

 

The Comanche looks great! What a good deal! I bet it will make a great run-around-town truck. 

Good to know.  I may one day weld-on frame stiffeners and I will be sure to unplug the ECU to do so. 

[89 MJ]

That sounds about right for the floors. 

[jeeper_chiefb]

I've had some old Corbeau sport seats that I took out of my YJ and I recently learned they make a brackets to install them in a MJ.  So I ordered a pair and they bolt right in with no problems at all.

 

 

[jeeper_chiefb]

I'm working on the console, but so far I've modified the automatic shifter bezel with a leather shift boot and added the switch pod for future needs.

[89 MJ]

Is that a 97-01 XJ console? 

[jeeper_chiefb]

Yes, it is a late model XJ console.  I made some mounting tabs to attach to the floor.  I've also ordered a replacement ash tray and I plan to adopt the hand brake for parking.

[jeeper_chiefb]

I added some headache rack bolt-ons in the form of a cargo area light bar, flashing recovery light, Hi-lift jack and a tiny crane from Harbor Freight to save my back. Also gave it some E-track and stake pocket tie downs, as well as made a small vice mount for stake pockets.  I plan to add a few more utility lights and some storage solution on the flatbed. 

[jeeper_chiefb]

It works pretty good for hauling a dirt bike or two.  I plan to make some wheel chocks for a more secure fit for the front tires.

[89 MJ]

What's with the other Comanche in the background?

[jeeper_chiefb]

This is a MJ I picked up from a local friend with the intent to build into a buggy.  It is nothing but a shell and now just sits as yard pollution because I don't have time for it.

[jeeper_chiefb]

I also have this beater XJ and built YJ.

[89 MJ]

Plenty of toys then! That MJ should make for a good someday project. I really like that YJ! I'm a big fan of those.

[jeeper_chiefb]

I’ve replaced a few things under the hood but I think the best change was the replacement idle air control valve. Still needs a valve cover gasket and more wire organization. 

[jeeper_chiefb]

It runs good but doesn't really drive as well as it could.  The 2.5L needs to use every bit of every gear and I feel a gear change would benefit the most.

 

I found these axles on marketplace that were in a XJ, so with little work they will find a new home in my MJ.  Currie 9" axles with 4.88 gears and lockers front and rear.  Also came with wheels and 33s, so I'll be lifting the MJ too.

 

The rear has these wedges welded on that I have never seen before.  Any one know the purpose of these plates; flush with the bottom of the axle tubes?

 

 

[neohic]

Dang! 9” front and rear is a lot of axle for that little 2.5. Definitely an upgrade. 

[jeeper_chiefb]

Over the weekend I got the old Dana 35 pulled out and converted the 9" from XJ to MJ.  

 

I plan to remove the load sensing valve and install an adjustable proportioning valve to use with my new rear disc brakes.

[jeeper_chiefb]

The stock front 4.10 Dana 30 looks to be in good shape, so resell should be easy. It's coming out starting tonight.