SilicaRich's Overland TJ Rubicon Build

[SilicaRich]

My grandfather has a 6 speed in his lj, I dig it haha

Happy hunting!

If you like your steep first gear in your NV3550 then you will love the 6 speed and its stupid low first gear. That will probably be the biggest thing I will miss especially with paired to my 241 Rubicase. However, 95% in nearly all offroad situations I encounter with my first gear as is, is extremely useless. Maybe if I did more technical trails I would appreciate it more.

Good news! Found a '79 300SD in Houston at a local salvage yard. Prices are not listed online but so I plan to call today and get a few questions answered. Only concern is that the vehicle has been sitting in this yard already for nearly 6 months so there is a chance she has already been picked through and could possibly have the engine pulled already. Fingers crossed, its a very clean salvage Benz so this could be the diamond in the rough.

 

[SilicaRich]

For those that are curious about the OM617:

Power; 120-125hp, 230-250 lbs/torque *Edit* ~170lbs/torque

Vs my 4.0 Power; 190hp, 230 lbs/torque

Obviously I am getting no power upgrade initially doing this swap, however, these diesel engines like most are easily tweaked for more power and fuel economy. I will likely do put a larger fuel pump and upgrade the injecters in the future. Something not exactly possible for the already exploted 4.0.

Doing a simple Google search, most of these swaps into Jeeps and Toyotas yield between 22-30mpg. This is a relatively broad gap but I would be more than happy and find the swap more than worth it getting 22mpg, major step up from my occasional high of 12mpg with my 4.0. Did I mean the OM617's powerband? Damn near identical to the 4.0 so no regearing required

 

[SilicaRich]

Well the call regarding the '79 300SD didn't go so well. The salvage yard crushes vehicles once they have been in the lot for over 2 months which is quite a shame considering the first glance condition of the car. Hopefully someone got to her before that. Gotta keep hunting.

 

[Jim K in PA]

Double check your numbers on that OM617.950. The HP is correct at ~120, but the torque is listed at 230N-M, which is ~ 170 lb-ft. Quite a big drop from the 4.0. The .952 was the highest stock rated turbo OM617 at 185lb-ft (250N-M).

Upping the power is possible, but not inexpensive. There is no bolt-on larger pump, and last time I checked there was only a couple of places for the custom pump modifications, and it was around $1200 or so to do the job. Larger turbo is needed also.

Then there is the custom oil pan to clear the axle (the OM is a front sump engine), remote mounting the oil filter (to clear the brake booster), adapter bits, etc.

I went through all of this for my LJ-R. I was going to go with the OM617 (had a donor lined up a mile away for $1500 for the whole car), but decided the juice wasn't worth the squeezin'. The best thing about the Benz diesels is they are high speed, so re-gearing is not necessary.

I hope it's what your looking for.

 

[SilicaRich]

Double check your numbers on that OM617.950. The HP is correct at ~120, but the torque is listed at 230N-M, which is ~ 170 lb-ft. Quite a big drop from the 4.0. The .952 was the highest stock rated turbo OM617 at 185lb-ft (250N-M).

Upping the power is possible, but not inexpensive. There is no bolt-on larger pump, and last time I checked there was only a couple of places for the custom pump modifications, and it was around $1200 or so to do the job. Larger turbo is needed also.

Then there is the custom oil pan to clear the axle (the OM is a front sump engine), remote mounting the oil filter (to clear the brake booster), adapter bits, etc.

I went through all of this for my LJ-R. I was going to go with the OM617 (had a donor lined up a mile away for $1500 for the whole car), but decided the juice wasn't worth the squeezin'. The best thing about the Benz diesels is they are high speed, so re-gearing is not necessary.

I hope it's what your looking for.

Thanks for that clarification, bad assumption on my part when reading on Wiki. Honestly, power is not what I am after when it is all said and done. IMO A Jeep is a Jeep and should be driven as such, if I wanted more power I would have bought a muscle car (not to say I don't think Jeep V8 swaps are cool). I read somewhere on PeachParts that it is possible to squeeze another 20-30hp out of these engines stock with some minor tweaking so I will look into that. I want to say it is more or less replacing/rebuilding neglected parts and gaining back factory horsepower rather than getting more than stock if that makes sense. I think the best to do would be to upgrade the injectors and look into an intercooler.

 

[SilicaRich]

https://austin.craigslist.org/pts/d/reduced-2-mercedes-benz-om/6385583446.html

Both were rebuilt, have turbos, and he is willing to sell them separately for $500 each. They are both from mid engine boats but no different than the engines found in automobiles. What do you think? Too good to be true?

 

[SilicaRich]

https://austin.craigslist.org/pts/d/reduced-2-mercedes-benz-om/6385583446.html

Both were rebuilt, have turbos, and he is willing to sell them separately for $500 each. They are both from mid engine boats but no different than the engines found in automobiles. What do you think? Too good to be true?

So I have contacted this seller and plan to meet him sometime when I get back for winter break. At first he was very reluctant to let me hear them run because he was afraid of them running off, but after a little convincing he said alright. I think $500 is pretty fair assuming one of the engines fits the bill, but I might try and see if he will take $450 or a little less.

These boat engines honestly might be better to buy rather than the engines found in the 300Ds. Likely less hours and these engines as is are much cleaner than what I have seen any other donors I have considered. If they are truly rebuilt, then this is a fantastic deal.

 

[SilicaRich]

Some explaining and reasoning

So I feel like there maybe some confusion with where I am going with this build, particularly with the consistent sudden changes with build plans ranging from simple mods, to a Cummins repower, to now a Mercedes diesel swap.

Here is the situation: Given I currently a Geology student in his junior year, I have recently realized I could graduate as soon as next spring, however due to minor constraints and me not realizing how many credits I actually have and not taking advantage of winter/summer intersessions, I could be very well be graduating a semester early next fall (still good from my parents standpoint because that is one less semester they are paying for ). To make myself marketable and actually pursue what I want to do for a living I will be going straight for graduate school for some sort of form of of Volcanology. The other side of the situation, the Jeep gets around 8-9 mpg in the city (would be a little better but NW Arkansas is has its fair share of hills) and 10-13 mpg highway (10-11 mpg when loaded). I simply cannot afford to keep the Jeep since I will be very broke for the next couple of years, meaning I would likely sell the Jeep after I graduate. That is something I don't want to do simply because of the time, money, and passion I have put into this vehicle. The engine swap is kind of my savior at this point reason for such haste. Goal is to have the swap done over the summer while I am at field camp.

Luckily I have a friend I work with that said he would be more than willing to do the swap. He can fab, weld, etc. His main challenge is going to be figuring out how to get my factory AC to work with the OM617, will require modification and a new sandem AC compressor that can pair to the engine. I have also decided to not swap in the AX15 for now to save expenses, luckily the adapter plate for the bellhousing works both with the NSG370 and AX15. As far as donor hunting has gone, I am still interested in the boat engine but wasn't able to look or hear the engine during the Thanksgiving break. Plan is to look at it over winter break. I have also found an '84 300D for sale with 178k miles that is very clean and runs and drives, however the owner says there is a knock. Given it is the OM617, this likely means the engine either needs the valves readjusted or possibly needs a new pump. There is even a chance that the owner simply doesn't know what a clunky diesel sounds like, of coarse there is still the chance of it being something more serious. He is asking $750 it is appealing given the condition and value to part out. It is in the same area as the boat engine so I will likely look at them in the same day.

 

[Mitch502]

I have forgotten if this was addressed, but is there a reason the 4bt isn't being used?

 

[Zeep]

I have forgotten if this was addressed, but is there a reason the 4bt isn't being used?

Hard to make that one fit, without cutting into the firewall. I've seen a build here somewhere. Have to look for the link!

 

[Mitch502]

Hard to make that one fit, without cutting into the firewall. I've seen a build here somewhere. Have to look for the link!

It's a pretty common swap though...or at least a popular one. One can buy a running 4BT bread/box truck for under $3000 most of the time....all swap components are available for purchase.

 

[JeepN95YJ]

https://cincinnati.craigslist.org/cto/d/95-mercedes-e300-diesel/6354484278.html

 

[SilicaRich]

I have forgotten if this was addressed, but is there a reason the 4bt isn't being used?

Brutal vibrations that with absolutely destroy a TJ's frame without any frame reinforcement, heavier than my current 4.0, Power to weight ratio is abyssmal (stock 4BTs have less power than the OM617), completely beefing up the drivetrain, and I would desperately need a regear to suit the powerband.

There is a lot of modification to remotely make a 4BT swap practical that doesn't fit my budget. I would honestly be better off chasing the 2.8 Repower dream once I got all the costs calculated for a 4BT swap. $3000 or less is my target goal to for the OM617 swap.

 

[BulldoginaJeepwithaColt]

Brutal vibrations that with absolutely destroy a TJ's frame without any frame reinforcement, heavier than my current 4.0, Power to weight ratio is abyssmal (stock 4BTs have less power than the OM617), completely beefing up the drivetrain, and I would desperately need a regear to suit the powerband.

There is a lot of modification to remotely make a 4BT swap practical that doesn't fit my budget. I would honestly be better off chasing the 2.8 Repower dream once I got all the costs calculated for a 4BT swap. $3000 or less is my target goal to for the OM617 swap.

Owning a 1998 TJ daily driver from new and having it just turned 20 years old this month I'm looking forward to seeing this swap happen. I have also like the other mods you have chosen as they were similar to mine and you obviously invested into some solid research on your optjons.

Do to some careless motoring through deep water crossings with too fast of speed, I just dropped in my 3rd engine. This "final" swap was an ATK 4.7 Baja Stroker this past February. I also have a Safari snorkel, but it is waiting to be installed.

Being a DD with a lot of highway driving and what not I have always wanted more power and quicker acceleration and I'm finally there.

Besides the engine swap, the best bang for the buck that I did, which was back in 2001 was I added a Borla header and cat back exhaust. I did the cat back first, and honestly did not notice a huge difference on power. It sounded better with a throatier sound and seemed to accelerate quicker. However, after the header install I noticed a lot more torque and the engine really woke up and sounded like a small V8 without that obnoxious Pep Boys fart can sound. To this day I really enjoy running through the gears and curb stomping the skinny pedal and just having fun.

With your future plans of more education that 3K can buy a lot of gas , I wouldn't feel bad about putting this swap off until you complete the schooling. The header could be added to wake your Jeep up in the meantime. If you are only looking for fuel economy, I never noticed an increase if anything I ended up burning more fuel by mashing the skinny pedal after that install and running to the pump more frequently to feed the new addiction !

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[WranglerWideJKU]

Isn’t it 170 lb-ft?


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