#99cherokee

Over the years my 4.0 has started to show its age and I've pondered the idea of doing a Mercedes diesel om617 swap. Well now my 4.0 is done and I bought a Mercedes 300D donor car as well as swap parts from Mercedesdiesel4x4 to adapt an ax15 to the om617 engine. My Xj came with an automatic aw4, which in its current state is in even worse condition then my 4.0. Over the years I considered a manual swap so I had a general idea of what parts I needed...However, its coming time for me now to make a choice on an ax15. There's a few for sale and Id like to make the best choice. What I need to know is are newer model ax15's at all controlled by the jeeps computer? Or can I pick up any one of them, bolt it up to my om617... and be on my way? Obviously an auto has much more interaction with the ECU and I even read that the 97+ model XJ's are much harder to convert from auto to manual. It seems to me as though those difficulties only really apply to someone who is keeping the 4.0 and In my case although mine is a 99, I will not have a 4.0 interacting with the ax15 and instead an 84 om617 turbo diesel.

The ax15 swap parts should be the last pieces to my puzzle for the om617 swap. What challenges will I face trying to make an ax15 work in my 99 XJ that was originally auto....or will I face hardly any as I am mounting it to an om617.

Some info I would like to put out there for people helping me are that for starters the jeep starter is still used with the swap. I will still be using the np231 transfer case which would indicate to me my speedo will work. I have an adapter for the oil pressure gauge to work and I will be able to modify the alternator so it works with the jeep wiring harness too. I'm imagining that the key is turned, starter spins, om617 comes to life and the computer reads nothing because the 4.0 isn't there. the key will fallback to the running position and my gauges will work, alternator will be charging and ill go on my way. (I wont be incredibly bummed if the tach doesn't work but I will attach the cps and see what happens)

Let me know what you think. All ideas brought to the table are appreciated. I've done a lot of reading on this swap and now the only thing tripping me up are some threads I read the other night explaining that the auto to manual swap on a 97+ Xj is much harder. Will I run into those problems?

SatiricalHen

The only wires coming out of an ax-15 are for the reverse lights. No computer interaction since you tell it when to shift and not a computer. Not sure how you're going to make the 99 alternator work since it is externally regulated by the ECU. Could use a GM one wire alternator or a Renix alternator since they're internally regulated. I believe the speedo and tach may go through the ECU too.

tinytrax78

no matter what ax15 you go with you should get a external slave bell housing

SatiricalHen

I've converted an internal slave ax-15 to an external slave. I'd recommend trying to get an external slave if possible because it's harder than just swapping the bell housing. You have to get a bearing retainer plate off of an external ax-15 which are hard to find and a little pricey.

#99cherokee

Good point with the alternator. I had planned on making a bracket to keep the jeep one but I did a little research last night and found lots of people use a 90's saab 9000 alternator as it has a built in regulator and is a direct bolt on to the Mercedes. I plan to keep the jeeps wiring harness in tact and to even give it power while the om617 is running. I'm hoping the gauges such as speedo and tach will follow suit. I could be wrong but I think the ECU gets all its info from the speedo gear in the transfer case and since I'm still using the jeep transfer case I think it would read info to the gauge cluster if the ECU has power. I've never tested this theory but I'm imagining in a perfect world it would work. If not I can always get aftermarket gauges. As far as the tach I'm thinking there's more to it since its an auto originally....maybe the CPS wont be enough on the communication end after the transmission swap is preformed.

Good thoughts on the GM one wire, definitely a great option. Looks like ill have to trick the NSS and then wire reverse lights.

XJwonders

If u need custom cables for that engine swap. Think of me.

#99cherokee

External slave all the way. the best looking ax15 I've found so far on CL is from a 97 wrangler. I heard the only mod I would have to do to it would be to "clock" the transfer case. I guess on wranglers they have the transfer case angled up a bit. Correct me if I'm wrong though.

XJwonders

That's right. The holes on the transmission tail housing are located slightly higher to allow the clocking of the t case. You can be inclined to elogonate the holes a bit to allow the transfer case to be clocked slightly lower to clear the floor pans.

#99cherokee

I would be curious if my transfer case drop would be enough to compensate for the different clocking on the wrangler ax15. Thanks for the offer with the cables. If not for this project I'm sure I need some for my Power Inverter project.

5-Speed

I had a Wrangler trans in my XJ. No need to "unclock" it for the XJ at least with a 231 t-case. There is an ear on the t-case that you can cut off and it will clear the body just fine. Done 2 of the Wrangler trans swaps in XJs so far and both worked out fine.

XJwonders

Cool. Never knew that.

5-Speed

Yep, I found out accidentally. I ordered a new AX15 and they sent me one for a Wrangler instead of a XJ. The t-case was fine before I swapped trans but after I swapped it, it hit the body. After a bit of searching, I found out it was actually a Wrangler trans. So it was either pull the trans back out and have them swap it, or modify the t-case to work. One angle grinder and 5 min later, all was good.

Edit - Here is what needs to be removed.

tinytrax78

heck if its clocked up enuff it would be a good time to put in a flat belly skid (tummy tuck) on

cleenrob

gauges in a 97+ can be a bit tricky if its a non-chrysler engine of the same generation. you have to retain the jeep ecu because it uses a complex signal over a CAN-BUS(or CCD-BUS i dont remember which) to tell the gauges what to do. the signal cant be replicated with out the jeep ecu and senders. the tach will be even trickier, youll likely have to get some type of crank signal emulator( i belive dakota digital would be the place to look)

personaly id build a custom mecedez-compatible gauge cluster to keep it simple
feel free to pm me, i did a different engine swap but the knowledge is still applicable to the diesel

#99cherokee

Been a little bit since my last post. I pulled the 4.0 out and have had more time to think. Mercedesdiesel4x4 is where I bought my adapter plate to mount the ax15 to the om617. They require that you get an ax15 with the 3/4inch input shaft. After a little research I found that the ax15 from 1992-1999 has that length input shaft. My concern is that although somebody may claim to sell me one from 1997 how can I be sure? Can I literally just get a ruler and measure it or is this something that isn't that easy? And one more thought to run through my mind was that I am curious whether I need a different shifter linkage for my transfer case and if so, what years are best or are they all the same for Cherokees with ax15's.