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Hi All, first post. New to Comanches but not Cherokees. Bought my 97 XJ stock in 05 and it's now a wrinkled, caged, one ton, rig on sticky tires.

 

Current daily driver is a 1980 Mercedes 240D 4spd. Lowered 2", 2.88 diff swapped for the stock 3.69, pump tuned and timing advanced. Yes, this is a 64hp/100tq motor and I'm guessing I may have added 15% to that on the high end with those mods but... it makes peak torque at 2400rpm and is a sweet highway cruiser. Gets 35mpg on my 60 mile round trip commute. It is rusty though... and a little too far gone to save. So, I have decided to combine my love of unibody Jeeps, manual transmissions, and mechanical diesels and swap the motor into an 86 2wd 5spd longbed. I am hoping that swapping the motor into a vehicle slightly less aerodynamic but a little lighter will keep my fuel economy number right about where it is now.

 

Back in December, a friend and I turned and burned from CT to TN and back in 28hrs to get the truck. It supposedly ran, but I never even bothered. The driver floor is rotted through but there is not a speck of rust anywhere else on the truck.

 

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I was able to acquire a motor to use for mock up from a local guy. Pretty much just a long block left exposed to the elements for years. This allows me to keep driving the Mercedes in the meantime. Using the Koch MercedesDiesel4x4 adapter kit.

 

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Next up, I adapted the Jeep alt bracket to the Mercedes alt bracket. My goal through the whole build is to use as many factory Jeep components as possible. With the alternator, it also simplifies wiring.

 

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This past weekend, a few buddies came over and we got the 2.5 out and mock up motor bolted to the transmission. The first issue I ran into was firewall clearance with the exhaust manifold. OM615 diesels use the same bolt pattern and port locations on the head but have a center dump so I ordered one on ebay. I used the passenger side stock Jeep mount unmodified and tried to do the same with the driver side but it wasn't possible due to clearance issues with the injection pump. I modified the stock bracket to move the mount back about 2".

 

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Next up is front oil sump clearance issues. A big bonus to using a 4 cylinder rather than 5 cylinder (and a 2wd rather than 4wd) is that it appears I will be able to notch the front side of the oil pan, modify the tie rod, and build a new trackbar and then maintain stock height. I want a 100% stock appearing truck and was very opposed to lifting the truck like most do in order to gain clearance with these parts.

 

After that, cooling system and exhaust. Will keep the pictures coming. Thanks for reading!

 

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More progress today. Got oil pan, trackbar, and ZJ tie rod all modified to all work together. Trackbar uses stock Moog poly bushings at both ends. Stock mounting points have not beedn altered which is a huge bonus. Next up is exhaust and cooling system.

 

Oil Pan

 

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Fabricated trackbar and heated/bent ZJ V8 tie rod

 

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Fit at full compression

 

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Fit at ride height

 

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Trackbar mount

 

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15 hours ago, kansashogan said:

Dang, you had to take a big chunk out of the oil pan! Looks really cool, though.

 

Yes, unfortunately I did. Rough math says I lost about 1 qt of capacity in the sump. Not much to be done to avoid it though, and have seen 5cyl swaps with even more removed.

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Fan shroud and exhaust done this weekend. All 2" pipe, straight through muffler from Amazon.

 

Shroud sucked. Not my finest work. But, I think it will work well.

 

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2" downipe. Don't think I could make another one fit this well again to save my life.

 

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nice work on the fan shroud.... like where your build is going..


Thanks! It did turn out better than I thought.

Couple updates tonight. Coolant crossover and K26 617 turbo. Have a friend with a 617 parts car with a shot turbo... planning to hack off cyl #5 from the manifolds and adapt everything else.

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Supper cool, would love to do a diesel swap. I’ve herd of guys doing 1.9 TDis but that just seems to small. Excited to see how this goes for you.

I’m pretty sure the 1.9 TDI makes more power in stock form than the om616, and the 1.9 has a decent bit of aftermarket support with higher stage tunes that can be used.


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Yeah, TDI definitely makes more power than a 616 and would likely get better fuel economy. I didn’t consider because of how cheap and simple the 616 swap is.

Updates from this weekend: fuel pump delete to fuel sending unit - Mercedes diesel has a lift pump at the engine. Took Darren’s advice and got some real motor mounts.

Steering, trackbar, and coils are installed and jack stands moved from chassis to front axle. Needs brakes and swaybar bushings before the front wheels go back on. Few odds and ends final fitted and a few things painted. Needs a new slave cylinder installed and heater hoses figured out.

Not much left after that until motor is pulled from the car. Which is going to be a sad day. Flywheel should be back from machine shop this week.

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  • 3 weeks later...

Lots of progress in the last couple weeks. Friday 3/22 was the last day for the old Mercedes. Sad day, but I discovered the rust underneath was even worse than I realized. It was time.

 

Modified flywheel with MercedesDiesel4x4 adapter.

 

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Buddy and I had it out in about 90min.

 

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Flywheel installed. Surfaced and balanced to zero.

 

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Modifications to upper oil pan to fit stock Jeep starter.

 

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There she is, in all her glory.

 

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I did not realize until I tried to bolt the adapter plate to my engine that the oil filter housing interfered. After some thought and researching a few options, I chose to just relocate the factory filter.

 

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Throttle cable bracket also fabricated and functional, no pics. Nothing special, extends Mercedes bracket to proper location to use the Jeep pedal cable. Glow plugs are now powered with a momentary switch on the dash that operates a typical starter type solenoid.

 

Got it running Saturday and the vibration at idle is intense. It seems like the idle is lower than it should be for some reason, not sure why it changed since it idled OK in the car last week. Little concerned about flywheel balance as there is a lot of speculation about internal/external balance on these motors. Nathan Koch who owns MercedesDiesel4x4 advised me to neutral balance so that's what I did... not ready to jump to that conclusion yet though. I will turn up the idle and get a few miles on it.

 

 

Left before it's ready to drive (aside from sorting vibration issue):

Vacuum shutoff solenoid

Accessory belt

Install cooling system parts and fill

Clean up wiring a bit

 

Plan is to take it on the trailer for VIN verification Friday morning and get it registered Friday afternoon.

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Machine shop checked, Mercedes flywheel is neutral balanced... just like the one in the Jeep.

Called Brown Dog. Started laughing as soon as I said the word diesel. Said they’ve been there and done that - nowhere near enough rubber for what I need.

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Test drive tonight!!!

Cooling system isn’t doing much. Only idiot light that never came on but hot radiator top and cold lower hose. Will pull thermostat tomorrow and run again.

Needs alignment, will do that tomorrow.

Once those things are done, it’s ready to put some miles on.

Powermaster starter cranks like a champ. Super happy with it.

Mounts pictured significantly reduced vibration but I don’t see them lasting long. I think I’m going to adapt the stock Mercedes mounts.

5spd is smooth and fun but 3.55s aren’t going to cut it. 3.73s in 5th would put me identical to where I was with the Mercedes in 4th, will have to give some thought to those or 4.10 especially with a whirly boi in its future.

It’s loud. No headliner and muffler doesn’t muffler as much as I’d hoped.

Going to be fun turning this into a comfortable DD over the coming months.

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Very close to DD status.

Before doing a complete configuration change on the motor mounts, I decided to try stock Jeep mounts. They didn’t change much, but... I found the motor side bracket was touching the unibody side bracket and took significant force to pry apart. Pulled bracket, sliced in half, bolted each half back up, tack welded in neutral position... BAM! Vibration that’s about 15% over what it was in the donor car.

That made a huge difference in driveability.

Slip yoke bushing a seal are shot, tomorrow’s job.

Stereo working with 4 new speakers
Sweet headliner (fatigue mat, idea stolen from ComancheClub)
Lots of misc interior assembly
LED instrument lights
H4 conversion

Needs tires balanced
Have bolts to replace door pins
No dome lights
Rebuild manual steering box w fresh grease

3.55s and .85 OD are useless. 3.73 would put me identical to where I was rpm/speed wise in the Mercedes. I think that’s going to need to happen, even with a turbo.

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In CT, anything 25 years and older requires only VIN verification if it was registered out of state. No safety inspection on anything. I got the VIN verified and transferred the reg from the Mercedes to the truck. The title from TN didn’t even mention fuel type. I know, we have it easy. Don’t have much else going for us in this state :)

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