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Oscar the TJ gets a CUMMINS

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4bt cummins tj
149K views 545 replies 89 participants last post by  TN-Mike-89YJ 
#1 ·
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.

http://i1223.photobucket.com/albums/dd506/10-3-tj/0524121348.jpg
http://i1223.photobucket.com/albums/dd506/10-3-tj/0524121348a.jpg
http://i1223.photobucket.com/albums/dd506/10-3-tj/0524121348c.jpg

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 (http://www.jeffdanielsjeeps.com) 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.
http://i1223.photobucket.com/albums/dd506/10-3-tj/IMG00700-20120612-1708.jpg

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.

www.jeffdanielsjeeps.com
 
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#28 ·
After getting the manifold cut and welded and the cleaning out the old bolts i moved onto clocking the turbo. Since the engine was originally a low mount turbo i have to rotate the cold side and hot side of the turbo.

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You can see that the discharge port of the turbo is pointing down and need to be 90 degrees from where it is now..

So i was able to remove the cold side and rotate it properly. However the hot side which is the exhaust side is so heavily rusted i cant get it to budge.
 
#29 ·
I have tried penetrating oil for two days, light heat from a torch, smacking it with a dead blow and cant get anything. Anyone have any suggestions. This is one of the last things to sort before i can start taking the jeep apart.

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#30 ·
I am currently soaking the turbo in a solution of Acetone and ATF mixed 50 / 50 . Anyone with ANY ideas would be much apperciated. I cant be the first person to have a rusted compressor housing.
 
#31 ·
Well while i am waiting for my turbo to soak in my mystery solution i started on the crankshaft sensor and cam shaft sensor. Both of these will allow me to use my stock tach.

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#62 ·
#35 ·
Ksilovich.. You make a great point about the turbo up so high. I am also worried about it. I chose the manifold that had a complete 90 bend in it rather than the 45. I had both in front of me and called shawn at Jeff Daniels and he suggested the 90. I like how yours sets down lower. Just have to wait and see what happens. Worst case. I get to cut and weld more on another manifold.
 
#36 ·
I am also thinking about running a snorkel kit for a YJ from ARB. The YJ snorkel exits the drivers side fender. I cant use my passenger side fender cause that is where my 4 inch exhaust is gonna exit. Much like marstache. ( spelling is prolly way off) i was very impressed by his build and love the way his jeep looked with that stak
 
#37 ·
Here are some pics from Jeff Daniels Jeeps webiste of a TJ with a high mount turbo which is identical to mine
 
#38 ·








Agian these are NOT MY jeep.. but just examples of what mine " should " look like when jammed back into the TJ.
 
#39 ·
For anyone looking to put a Cummins in your Jeep check out kssilovich build. It is awesome. I wish mine was going that direction. AWESOME JOB ksilovich
 
#43 ·
JKNATE
Contact Shawn and Dan at jeff daniels jeep and discuss with them what you have and want to do. They sell kits for your JK. On their website the have one or two JK's with a cummins and pictures also. Good luck
 
#44 ·
UPDATES UPDATES UPDATES

So the last couple posts I was waiting for my mystery solution to work its magic. WELL IT DIDNT WORK. So i contacted Stacy and Columbus Diesel Supply told him my dilemma. He told me to bring the turbo on in and he would get it apart. I was very skeptical because i already took it to one shop and they laughed at me.

To my relief Stacy came through and got the exhaust housing seperated. Fast forward to this morning. I attempted to clean and clock the turbo so it would work for my application. Well i am no turbo builder for sure.. some how i got the exhaust housing on crooked and the fan blades where hitting bad!

So again i went back to Columbus Diesel Supply for Stacy to rescue me. Stacy and another mechanic saved my as* . They took my turbo apart again sand blasted my housing and cleaned the center housing and re installed the housing FOR FREE!!!!!!!! I couldnt believe it..

The turbo spins like a brand new one. I couldnt be happier.
 
#45 ·
So feeling that my karma bank was now empty i figured i better go get parts like oil filter, fuel filter , thermostat , front cover gasket and the like. Well luck strikes again. Turns out there is a Cummins dealer about 15 minutes away... I also stopped at NAPA and picked up some cummins beige spray paint in a rattle can.
 
#46 ·
10-3-TJ said:
JKNATE
Contact Shawn and Dan at jeff daniels jeep and discuss with them what you have and want to do. They sell kits for your JK. On their website the have one or two JK's with a cummins and pictures also. Good luck
I'm a long way out before that happens. I'm just a very big fan of diesel engines, and want they offer to our sport. Great low end power and fuel mileage.
 
#47 ·
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Above are the pictures os my engine as i prepare to fix the KILLER DOWL PIN. Sounds so terrible, and certainly can be if this little guy falls into the gears.

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Here is a picture of what cummins came up with to keep the dowl pin where it should be.

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I put some red lock tight on the bolt and sunk it home. Then used a screw driver and hammer to make sure the tab wss securely seated.
 
#48 ·
Then becuase like most guys on here i cant leave well enough alone , I decided to strip and repaint my front cover and crank pully.

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I used a rust preventer primer and two coats of color.

I plan on putting everything back together tomorrow morning and will post more pictures then. The only thing left to do now is find a stainless steel pressure feed line to the turbo and a oil drain line, also have to cut the old drain tube where it mounts to the turbo becuase it hits my exhaust manifold. Prolly gonns start on a down pipe while I have the motor out also.

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#50 ·
Jeepwrangler89, I am trying to get it ready by the Jeep show. Off the top of my head I think the show is Sept. 22ish !?! that gives me a little under two months. I feel like it should be done, but we all know how things go. I am planning on going if its done.

I have nothing but good things to say about Jeff Daniles crew. I believe they are honest, hard working men. We need more USA companies like them.
 
#52 ·
More updates.

I got a lot done this morning. Got the front cover all painted last night and today i pressure wahed the block with degreaser and painted the block. Still have the valve covers to clean and paint and the exhaust manifold to clean and paint.

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