Build OM 617 benz in a jeep cherokee with AW4
 

Hi all this is still underway, So I am starting in the middle. Putting a Normally aspirated MB 617.912 from a 1976 MB 300D with a 115 chassis, Into a 1996 Jeep Cherokee XJ 2 door 2wd, with AW-4 Automatic transmission with lockup Torque converter. I am using a Koch adapter kit for the AW4.
I have been wanting to do this for a long time. I originally wanted to make an adapter plate to use the jeep AW4, and torquconverter, adapted to the MB flywheel, flex plate and MB starter. I only got as far as a pilot bushing for the TC. I got hung up on how to modify the jeep TC to take the MB flex plate bolt pattern. I wanted to weld new mount lugs on the Jeep TC, then I got scared because someone said that if you weld on the TC, there is a paper liner in the TC that will burn and cause the TC to fail. So after you weld o the TC you have to have it rebuilt. Then I could not find a place to get the jeep TC rebuilt at a reasonable price. And there my project stalled.
So thanks to Mr. Koch, my project is no longer on the shop floor; it is now in the jeep and running, or was running until today. technically it is still running. BUT
The first part of the build went very well and smooth. except the clearance from the nose piece on the Jeep TC was a tiny bit too tight in the kits flywheel adapter. A little crocus cloth and we were back in business. Fabbed up a set of forward engine mounts using the old jeep mounts with the horn cut out, at least for one. the other was a complete new fab. there should be some pictures.
I used the stock MB down pipe for the exhaust. I took the MB pipe and cut it up into pieces, removed the bits I did not need and changed the angles where necessary and welded the down pipe back up. I still need to add about 18" to the down pipe to get it connected the left over jeep pipe that I cut just in front of the CAT. That all went pretty smooth as well.
The Jeep starter spins the MB just fine. I found a electric solenoid vacuum switch to use as a engine shutdown, that is going to work, but I have not wired it up yet. I also have a momentary on push button and a Ford starter solenoid to run the glow plugs. The engine started up immediately.
The first 2 starts I used starter fluid not the glow plugs. Yes I know that is a NO NO. and I think I really finally learned that lesson. On the second start. the engine started to clatter at idle. then it got worse, and worse. This engine was sitting for 16 or 17 years before I got it, then it sat on my shop floor for another 7 years. The end of the clatter was using a hot soak SeaFoam treatment direct in the secondary fuel filter. That got the injectors to stop clattering.
Unfortunately I was so preoccupied with the clatter and the injectors, and worriying about permanent engine damage from the starting fluid, and the clatter was so loud, I could not hear the flex plate going bad. I had tightened the TC to flexplate bolts plenty tight I thought, but I did not locktight them as I was waiting to make sure I did not have to take the engine out again. Well with maybe 10 minutes of run time on the engine. The TC to Flex plate bolts have come loose. only one was left installed. on their way out the bolts buggered up the Flexplate pretty badly. So that is where we stand today. I need to pull the engine back out and see how bad the flex plate and TC are damaged. I know the TC bolts are shot.
Hopefully I can just re-drill a new TC bolt pattern into the Flex plate without removing it from the engine. and hopefully the TC bolt lugs are not damaged beyond use. I kind of have my doubts on that, but we will see when the engine comes back out.
Below are some pics of the build so far.
Next after the TC/flex plate repair will be getting the Front steering gear and suspension to clear the MB oil sump. The I will have to work on transmission control for the AW4.
I know there are a few more AW4 conversions going on. Does anyone have any news on Transmission control. If anyone is not yet to the TC bolt torque learn from my mistake and make sure you locktight the heck out of those TC bolts even before the first start
overall the build has been fun, frustrating but fun overall.

couple quick thoughts:

1. good on you for throwing the hammer down on the swap!

2. dude, I really hope those mounts in the picture aren't the final product that is holding your engine in. they need A LOT more structural reinforcement.

2. the aw4 transmission has its own control box. it is mounted under the dash kick panel. to re use it, you just need a rpm signal, and a speed signal. you can always dumb it down and go to a 1987-90 mechanical speedo cable with a pulse sensor built into the cable(used for cruise), and find a spot to run a magnetic pickup off your pump drive gear or the like for the rpm signal. you could even use the blue speed sensor in the tail housing of the aw4 for a speed signal, if you knew how to convert it.

Thanks for the reply. Sorry to say yes the engine mounts are going to run like they are for now. The mounts are the same weight/thickness of steel as the original jeep units, although welded and not stamped. Don't forget I am running a stripped down Normally aspirated benz motor which in full running dress weighs 510#'s. The jeep 4.0 that came out weighed 465#'s. I have had the engine in and out of the jeep sitting on these mounts several times, running and not running, in gear and out. I have not had any flex, bend, or shift at all. Granted the loads are not actual driving loads. But this is a 2wd street jeep, not a x-games jumper. This steel was on hand clean and ready to go with zero cost. If I have a problem I will re-engineer when I need to.
Thanks for the help on the trans shifting. I am hoping to be able to get a working engine speed signal from the OEM flex plate, which already has a sender looking at it, and also a jeep road speed signal from the AW4 tail housing. I also thought I needed a throttle position. I will have to figure out a way to get the Jeep TPS to work. my original thought was to pull the butterfly valve out of the jeep throttle body, so there is no restriction, and extend the jeep wiring harness and hook the whole jeep TB unit up to the MB intake. The new MB intake is on the far side of the engine bay from where it was with the jeep engine. That was a pretty long distance to try and adapt, and rig up a aux throttle cable, so the jeep TPS sender would move with the benz speed lever.
As it sits now, the jeep throttle cable fits easily into the MB system, and it still moves in the same direction and all as the old jeep stuff.
I am thinking now it will be easier to make a small braket just to hold the jeep TPS, and a little custom axle to drive the sensor, and somehow get that all in line with the new throttle linkage.
when i get the engine back in i will try and get a pic of the throttle linkage

thanks again for your input

SO if I am to understand you, your new engine weighs more than the original, yet you took nearly all the strength out of the engine mounts?

not to beat you up here, but I am very familiar with the xj mount design. all the force is distributed evenly into the frame rail. yous is leveraging off of a 1" sliver of 1/8" with zero reinforcement. you could take a 2lb sledge and bend those completely off the frame. what would happen if you put a jack under those mounts? could you jack up your truck? look at where the force is applied.

there really is no reason to have it bolted in at the top the way you do, your will fold right at that first frame bend before those bolts ever see any load.

what can I say moneypit. my truck my designs. Thanks for your concerns. I have seen several other engine mount designs for this exact conversion. I have only heard of one design having a problem, and it was redesigned to be a bit heavier than what I am running. one design I saw is very very similar to what I have done, and I did not see that until a few days ago. So 2 independent people came up with almost the exact same solution to the problem.
I am aware that these are not the strongest engine mounts in the world. I am willing to give them a try as they are.
This is a first draft at this conversion. I am planning a 2nd project with a turbo motor after this one, I hope to learn from my mistakes on this one and improve on the 2nd conversion.
As I said. This is a light duty street vehicle, I guess we will see what happens.
I have much bigger problems to fix with the front suspension and steering clearance issues than these engine mounts.

show me. Id be very suprised if they had a giant hole where the support for the mount sits, and no lateral support.

ok moneypit. How about I tell you where to go look for the picture, and you let this subject drop. As I believe I have made my position pretty clear, and you have voiced your opinion well enough. I do see your point, and the comanche mount has had the hole welded over with a bit of plate, which I guess will make it a bit stronger. Regardless, I am still going to run mine as is, until I see some evidence of a problem.
so to see the other mount do search for " comanche" on superturbodiesel.com. just my opinion, but i think the 2 mounts are pretty similar.

trying to help you out, as you obviously have no concept of load. your mounts are nothing like the ones you linked to. good luck with that, I hope your motor stays where you put it, after all, its only 60# heavier than original.:argh:

just a update. I have started driving the jeep. no problems with the mounts so far. I am still just going around and around the block. I solved the steering and track bar problems . That was not too hard. I just have to bite the bullet and jump in. it seems easier to make stuff from scratch that to try and modify pre-existing parts. I did notch the oil pan, I don't think it helped much. the real help for me was to move the steering box. I made a offset drop mount. the pics are not too easy to see, but it seems to work just fine. The mount was made out of 2 pieces of 1/2" plate. I mounted one plate in the OEM spot, then mounted the other piece of plate to the steering box, and then put the box where I wanted it and tacked the crap out of it, removed it all, and drilled and tapped the 2 pieces of plate together, so I can take it apart if I need to. It will take some grinding to get the heavy tack welds off, but it will come apart if needed.
I am very happy that I was able to get the manual steering to work.
I had a little bit of problems blowing water hoses apart at the reducer adapters I made. I switched to steel from aluminum and so far so good.
I have not figured out how to get the trans to shift in " D " but I don't know if anyone else has had success with that either. the Trans shifts manually minus 2nd gear if you just disconnect the trans from the computer.
I still need to get some power to the TC lockup solenoid. I am going to wait to get that after I pass state inspection.
I am chasing bugs in the chassis to prep for state inspection. you have to expect problems when you start with a $100 chassis, So brakes, and exhaust , light bulbs, and wipers. all that little crap adds up to $. Here are some pictures.
If anyone has gotten a AW-4 to auto shift in drive, on either a Cherokee or Wrangler, I am very interested in seeing that. I am going to try and get a signal from the throttle position sensor, but the jeep sensor has 90 deg of movement, and the MB linkage has quite a bit less rotation. I am thinking about a double bell crank set up to get more travel to the jeep TPS. any thoughts on that? from any other applications

Thanks

Keep truckin dude. You're doing fine. I've done several of these swaps, to include this one, and those mounts are fine. I've only seen motor mounts fail when they are allowed to "oil can" due to lack of right angles. This engine is not that heavy, and it makes very low torque. You're good. If it was a 6bt Cummins, I might beef them up a bit. The 6bt is 1100lbs and makes 4 times as much torque.

Thanks DieselGreg. The jeep passed TX state inspection a few days ago. So I am not confined to running around and around the block.
DieselGreg, Do you have a conversion running with an AW4??
I now am having shift point issues. I get auto function in D, but only when the e-fan is switched on, The shift points are all late. I don't have a working TPS ( TPS is just hooked up to the harness but not to the throttle ) and I lost my speedometer I have not been able to get to full highway speeds because of a death wobble when I applied the brakes from about 50mph. On a positive note no bump steer that I noticed, so that means I got the trackbar right.
I need to get a steering damper that does not use the OEM mount location on the draglink. I know they make dampers that use u-bolts to attach to the axle housing and then the draglink. I just need to find the correct size.
I am considering removing the 2" coil spacers, and going back to original ride height as well.
Once I offset and dropped the steering box, that got rid of all the steering clearance problems. (well I do have a death wobble). The wobble is fairly common on the xj's. I had one on my DD xj.

So I need to sort out the wobble, and the speedometer, and I hope to hit the highway.
I ended up with a TinyTach, and that works very well. Also I have a direct reading oil pressure gauge and a electric temp gauge. A nice little black pushbutton for the glow plugs, and a red button to shutdown. I ordered a 3-way solenoid valve from the internet, looks a bit like the one johnnyd had with the 4mm push fittings. But it was vented all the time, I ended up using the stock EGR vent solenoid for engine shutdown, and I drilled a highly calibrated orifice in the shutdown side to ( the smallest drill bit I had) to act as a vent. the hole was a bit big so I closed it up some.
So far it is all working ok. I think the mounts are going to be fine as well. I have to say I am still a bit wary of the reliability, It did not help that the jeep I started with was kind of a POS, that had been sitting for a long long time as a non runner.

I am not sure what to do about the speedo. In '96 it was already electric

The last pic is of the new jeep I picked up 2 weeks ago, it is a '01 w/125k miles all original, no damage. Not sure if I am going dieselize this one yet it has a 5 speed and gets a solid 21mpg on the hi-way already. I need to see how the '96 does first

sweet build hoping to do my Cherokee that way

as a relatively simple solution to your speedo issue, you could revert back to the older style (pre 91) guage cluster. they had a mechanical cable running the speedo. just make sure you get the Tcase drive with it- anything older than 1993 is fine for that part.

Youll need to change around some wires to make the new guages work, but none of it is a big deal.


for your death wobble, sounds to me like your Toe-in is off. I like to set my toe-in around 1/8". (narrower in the front)


And, as a pre-carnage prediction, this is the area your motor mount will fail first. where circled, it will pull out from the body. there is also nothing keeping it from moving upwards.


But Im happy to hear its on the road! swapping a diesel into an xj is a bit of work, its exhilarating when it goes down the road under its own power after sitting in the shop so long.

Edit: I find it interesting that your 4 gear works when your Efan is on. the E fan relay is switched with a negative ground, could that be grounding other circuits in the fuse block?

HI Moneypit. Thanks for the suggestions on the speedo, and the deathwobble. I believe you may be correct on the Toe-in. I need to get an alignment. It does not help the death wobble that the jeep sat for about 10 years. Pretty much all the rubber bushings in the front end are shot, and it certainly does not help that there is no steering damper installed. I feel pretty confident that I can sort out the death wobble with out too much trouble.
On the speedo I really don't want to have to go to a mechanical speedo. This is a 2wd SE model, so no gauges , just dummy lights, and I did not hook them up as I went with direct reading gauges. I think I can sort out the speedo, it also will just take some time ( which I have run out of for a while).
I was surprised that the trans shifted at all in "D". I fully expected to have to make a trans shifter. To get the trans to shift manually when the shift lever was moved, and then have a push button on the lever to activate the TC lockup. I am even more surprised that the trans is shifting and the speedo is not working.
To get the E-fan to work, I just jumpered a switch onto the bottom of the Fan relay on the back side of the electric junction box. So yes it does work by grounding that one wire. I forget the color. Most all of the electronics are working. For some reason the radio will not keep its memory any more, and it did for a while. And the front windshield washer is not working, but the rear is. That is all I can think of at the moment.
I still think the mounts will be fine. I have hit some pretty good bumps at speed already, and they are steady steady, with no signs of movement at all. You will be the first person I tell if they fail.
sorry I got a go

The merjeep saves the day. I just got home from work; gone a month. the Dakota was a no start, NO spark. I guess been sitting in the salt a bit too long. I started trouble shooting, I got a computer code about a defective autoshutdown relay, then I was checking all the electrical connection, and the oil pressure sender fell apart in my hands. So the Dakota is DOA at least for a bit.
I put a fresh battery in the merjeep and she fired up immediately; I mean rite now immediately. The merjeep has been sitting unstarted untouched for almost a full year. so there is something to be said for a computer less everything else LESS Mercedes diesel converted jeep. It might not be the most comfortable vehicle without AC or power steering, but the thing starts and runs every time so far. This engine sat for over 16 years before I bought it; and it fired up then as now. Immediately.
I will get a fresh state inspection sticker on the jeep tomorrow and put it back on the road until I can get the Dakota sorted out or the Kubota jeep finished. Most likely the Dakota.
But you gotta love the MB they run forever