Converting 99 TJ to Diesel?

S

socal_rob

New member
Can anyone offer any pointers or thoughts on converting a 99 Wrangler TJ to diesel? I've read up on it a bit and it sounds possible. Has anyone here done it? I also read that Jeep was planning (pre-economical meltdown!) to offer a diesel engine upgrade kit for YJ/TJ, etc. using the same diesel engine they once offered in the Liberty.

At this point, I'm not terribly concerned about the cost. I know it will be expensive, so I don't need to be dissuaded on that point. I'm more curious to hear from some of you more experienced grease monkeys what I'd be getting myself into from a feasibility standpoint. Also, what kind of performance issues (good and bad) might I encounter? Finally, my primary goal is to fuel it with biodiesel as the fuel is readily accessible where I live.

FYI, my TJ is a 99 Sport w/ RE 5.5" Long Arm lift, D44s, ARB front and rear, 35" tires.

Thanks!

-Rob
 

One of my friends bought a bread truck with the 4bt cummins for $2,500 and swapped the whole drivetrain over into his yj. If you can weld and fabricate it's no worse than any other engine swap. He kept snapping rear axles but after upgrading the only real downside on the trail was how heavy the front end was. On the road he got 30+mpg.
 
You do not want to use a bio diesel on the KJ diesel engine. You will end up replacing all the injectors and possibly the injection pump after a little while of dumping bio diesel on it. I've seen a lot of the 5.9 and 6.7 cummins and the italian diesel used on the KJ's fail due to the use of bio diesels. The older (Pre 05) 5.9 cummins seems to hold better than the newer ones when bio diesel and farm grade diesels are used. The Wrangler 2.8 diesel has been out since 2007 but not here in the U.S. . The plan of releasing the JKs with this 2.8 has been an ongoing rumor. The plan is there, they just don't know if it's going to meet the U.S. standards and that's why they are trying this in the export market only. If the JK's does make it with a diesel, it will be the 3.0 mercedes powertrain thats currently in the new gc's.
 
Hey Rob,

The only thing you might have a real problem with is emission laws. The TJ was never offered with a diesel in the US because it would be classified as a light duty diesel truck. So check your state laws first. You might have a easier time with converting an early YJ (which are hard to keep running as stock anyway). Search this forum and you'll find some other info. My .02 has always been that the Cummins 4BT is too heavy and makes too much torque for the Wrangler / CJ. Other, smaller engines might be a better choice. Volvo, Mercedes, Isuzu, and Toyota all made good small diesels. Watch out for the Japanese ones - they might turn "backwards". One other site to check for info is jeeps2diesel - many successful conversions there. A diesel Jeep would be awsome... Something I've always wanted to do. Best of luck - John
 

I have a 98TJ with a Cummins 4bt engine. I am using the AX-15/231, but I swapped axles to D60 front and a Sterling 10.25 rear, detroit lockers in both, 38.5" tires.
There are several other engines you could use that are about the same size, but lighter. The 4bt weighs about the same as a fully dressed big block. I only own diesels and have tried bio-diesel and WVO extensively with mixed results. I have come to the conclusion that after all the modifications, trouble shooting, variances in quality, replacing prematurely failed parts, etc. etc. I have gone back to regular diesel, but thats just me.
What was said about the legality of swapping a diesel into a chassis that never had one is very true in some areas. So check it out before you start spending money.
 
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