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10-3-TJ 07-05-2012 11:35 PM

As the title suggests I am assembling the parts to put a Cummins 4BT in my 98 TJ. I Have been reserved in starting a build thread just because I don't want this thread to become one which is started and then all of a sudden it just magically stops.

I look forward to sharing the information which I have learned and intend this thread to be a guide for people who also want their JEEP to roll some coal.

A little background on the Jeep first. I bought my TJ bone stock three years ago for 5K from a grandfather who was saving the Jeep for his grandson. As life would have it the grandson wanted NOTHING to do with Jeeps because they are loud, ride like log wagons and bad gas mileage. Personally I was happy the kid had a terrible opinion because I got the Jeep for a decent price.

I couldn't wait to start turning the wrenches on the Jeep which my wife named Oscar because of the forest green color and she thinks that the Jeep makes me grouchy when I work on it. The first on the to do list was a Rough Country 2.5 inch suspension lift with the 3/4 inch poly spacer, Advanced Adapters slip yoke eliminator, Tom Woods drive shaft ,stinger front bumper from TKH fab and 33x12.50x 15 BFG muddterrians on Cragar Soft 8's.

The Jeep has been pretty much this way until about the last year when I upgraded the rear Dana 35 to a Ford 8.8 limited slip and a front Dana 30 high pinion which is Aussie locked. Also re geared the axles to 4.10s. This pretty much brings the mod list to current minus small things like cab lights, and Raptor lining the tub.

Approximately 5 months ago my stock 4.0 engine has been making some killer sounds. The lifters are crazy noisy ( which I know is common) I have been getting a very bad knock on the rear two cylinders. It was suggested by a couple guys at work that I was hearing piston slap. I dunno though they couldn't explain what piston slap was.. Also the engine has been running junky and honestly I was tired of chasing problems with the engine. I would get one issue fixed which led to another.

I contemplated doing a stroker and V8 and have been running through many pages of information on everything. I finally made my decision on a Cummins 4BT diesel. I will be very honest, the diesel is not the cheapest engine swap to do but for what I wanted the Jeep to be in the long run, the diesel was best choice.

I contacted Jeff Daniels Jeep ( and spoke endlessly with Dan and Sean. Both Dan and Sean own the company and are EXTREMELY polite, personal and educated in putting Cummins in YJ's TJ's and even JK's. I was very impressed with both of their knowledge bases of the Cummins engine and Jeeps.

Dan found this engine for me.

This engine is from a bread truck and is 80,000 miles fresh from a Cummins Recon. The engine has an H1C turbo and is non-wastegated.

10-3-TJ 07-05-2012 11:49 PM

The 4BT has a VE pump which was rebuilt during the recon as well as the injectors. I plan on running a high mount turbo using either from a 6bt 5.9 exhaust manifold and cutting off one exhaust port on each side or buying a new one from Steed Speed although Steed's are a bit pricey.

Dan from Jeff Daniels jeeps has absolutely everything you would need when putting a Cummins in your Jeep. From engine mounts, crankshaft rings and cam shaft rings which will allow me to use all the stock gauges including the tach. Fuel pump check valve which will utilize the stock Jeep pump basically as a lift pump to assist the 4BT's engine driven fuel pump. The check valve will pop and will recirculate the fuel back to the tank via an additional fuel line which enters the fill tube close to the tank, to prevent splash back. The 4BT's fuel pump does not require an additional pump. This is just the way I chose to do mine
There is an additional way to do the fuel pump using only the 4BT's pump however that involves drilling a hole in the stock fuel pump and running a piece of stainless tubing as a pick up tube. I didn't go that route because I just put a new OEM fuel pump in which I couldn't stand to drill a hole in!!

Anyhow I will have more pictures and information coming soon. My engine and pieces will be shipping from Jeff Daniels Jeep either Monday or Tuesday of next week. I am shipping the engine using a local freight company R and L shipping. For a 1200 pound pallet from Pennsylvania to Ohio was $350 bucks NOT BAD AT ALL!!!

10-3-TJ 07-05-2012 11:53 PM

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More pics of Oscar

10-3-TJ 07-06-2012 10:35 AM

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Here are a couple more pictures of the 4BT

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The person i bought the motor off of had already taken the time tio clean and paint it. One more thing i dont have to do.

10-3-TJ 07-06-2012 11:09 PM

I talked to Dan and Sean this afternoon and the 4BT will ship on Wednesday and will arrive to me Thursday. Now starts the scary part, pulling my jeep apart!

jeepin82 07-06-2012 11:15 PM


Originally Posted by 10-3-TJ (Post 13824416)
More pics of Oscar

The Look out in Maysville at Bigrock off road!

Ive been there many times. I live in Washington Court House about 1:45 min from big rock!

10-3-TJ 07-07-2012 10:36 AM

Jeepin82, you are right. That was taken last weekend at Big Rock.. I live about 2 1/5 hours north of Big rock. It wasan easy drive down. We spent five hours at big rock and saw maybe only a 1/3 of the trails. My buddy who went with us took his stock 2011 JK which didnt do to bad. We are going to plan another trip ounce I get the diesel in. Are there more techinical trails at Bigrock? everything we found was either easy or CRAZY steep and looked like they were four wheeler trails.

zortfellow 07-07-2012 11:39 AM

So big rock is cool I'm deployed now but I live in Cincinnati on the east side so not to far

10-3-TJ 07-07-2012 02:42 PM

Big rock is fun for what its worth. I enjoyed it. I only got to see about a 1/3 of the entire park. Bigrock advertises that its nearly 2K acres. There is so much to see and drive that its hard to judge what other trails are out there. The main trails are basically gravel rock and dirt trails which led to crazy steep drop off's. Steeper than i would ever venture into. When you go make sure you have all day to spend cause time will fly.

10-3-TJ 07-07-2012 04:22 PM

Just got done ordering a Daystar one inch body lift from and ordered a transfercase linkage from advanced adapters. I have heard that guys running a body lift get a bind in the shift linkage for the transfere case. And for 30 bucks i feel its good insurance.

10-3-TJ 07-07-2012 04:28 PM

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10-3-TJ 07-07-2012 04:32 PM

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Here is the picture of the shift linkage and the previous photot is of the body lift. I like the daystar because it completely replaces the entire stock jeep bushings

sandboxphil 07-07-2012 06:52 PM

SUBSCRIBED! :thumbsup:

zortfellow 07-07-2012 11:56 PM

Yeah I'm thinking I'm a fire fighter so I would just use my 48 hours of drive out in the morning camp over night thanks

10-3-TJ 07-08-2012 03:55 PM

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Okay so R&L Carriers based out of Wilimington Ohio will be picking up the engine on Wed. And i will have it Thurs.

I have some options on how i can run my turbo. Currently the stock setup is a low mount turbo manifold with a rear mount. So basically the turbo mounts on the rear of the manifold and on the bottom. This stock setup will push my down pipe into the firewall. My options are to cut and weld my firewall to make the down pipe fit, which i am not oppossed to, just takes longer.

My second option is to purchase a used 5.9 6BT manifold, cut off one port on each side and weld it shut. Then flip it and use it as a high centrr mount. I have no prices on used 6BT manifolds. There are plenty people who run this setup and have zero problems.

Third option is from a company called Steed speed performance. They are a Canadian company who cnc mills 4BT manifolds out of stainless. As yoy can imagine they are pricey. About 620 here are some pics of their manifolds

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