86 Diesel MJ to VW TDI conversion

[Raven]

I beg to differ. Fuel economy is one of the reasons to do any diesel conversion. An example is one of my old land cruiser station wagons. It averaged 12mpg on the highway. About 9mpg in city and about that offload. When converted to a diesel I was getting about 26-28mpg. Much longer range and better torque to just let it idle over obstacles off road. I don't rock crawl. Prior to swap on the highway with a 50 gallon long range tank full of petrol is about 600 miles. After my diesel swap 1300 miles on a tank of diesel give or take 150 miles. There are other reasons to go with a diesel swap but these are my own. Recouping costs isn't something Id be interested in as I would be very content on the finished product. You just don't do these conversion to recoup any of the costs. 

[johnj92131]

Filled the fuel tank for the first time since January 30, 2019 today.  Took 20.976 gallons.  Odometer say I traveled 982 km since January 30 fill up.  Applying my GPS verified correction 111.7 means a real 879.1 km or 546.27 miles   That is 26.04 mpg for this tank of mostly around town short driving. Cost of diesel was 3.999 per gallon, $83.88 at the pump. 

Comes out to $.1535 per mile for fuel cost.

 

 

[shelbyluvv]

That's simply amazing. I know when I drove around to load it on the trailer it had a ton of low end grunt and didn't take much throttle to make it move. I'm damn impressed with the truck. I'd love to own that one some day.

[Guy with a Jeep problem]

outstanding build can you post pics of the coolant hoses. Thank you 

[TDI_MJ_17]

So some of you may know, John has passed away. I am his Grandson and have been blessed with the Comanche to live on! 

When i got it, it had just shy of half tank, drove it around a little longer and filled it up. it took 20.8 gallons, came out to ~27 MPG with the GPS correction. 

I have been dealing with coolant temperature since ive got it, spoke to the builder and was advised not to exceed 225 with the TDI. It is consistently getting hotter then that, so ive ordered up radiator, thermostat, and the works to make it an open cooling system. Those parts should be in tomorrow afternoon.

On the drive home tonight, we lost the throw out bearing. 

 

 

On another note, the peeps at O'riellys got a kick out of the truck. Every employee was outside checking it out.

[TDI_MJ_17]

On 1/1/2020 at 7:43 AM, Guy with a Jeep problem said:

outstanding build can you post pics of the coolant hoses. Thank you 

They are a combination of hoses, Matt had made a good part of the upper and lower rad hoses out of metal, cut/bend/weld to where they needed to go, connected with short runs of rubber hose. The tank on the fire wall seems to be set up just like factory

[Pete M]

8 hours ago, TDI_MJ_17 said:

On another note, the peeps at O'riellys got a kick out of the truck. Every employee was outside checking it out.

 

better get used to that.  it'll happen more and more.  

[TDI_MJ_17]

Well, It was a fun night of repair. Got the transmission ripped out of it Saturday morning and replaced the throw out bearing with a new Cast Iron unit made by National. Got everything back together without much of a hassle.

While having in my stall at work decided to take on the coolant temperature issue, replaced the radiator, thermostat, and flushed all of the coolant out. Noticed it had the expansion tank and a fill neck on the radiator, assumed that was not the best way to have things, so got rid of the expansion tank and mounted up a new universal over flow reservoir of the radiator. Filled it back up with the some fresh G05 coolant, drove it home and never got passed 205 degrees coolant temps!! Yeah! 

Get home and found a bunch of steam coming out, poped the hood and two hoses in the rear were pin-hole leaking under pressure 

Tomorrows project will be breaking down all of the hoses such as heater core, oil cooler, etc and getting them all replaced some fresh rubber. 

Down the line i plan to get my friends over at CE Auto Electric supply help me clean up all the wiring on the truck with a set of custom built power and ground cables, and a custom relay box. I used their customer cable builder to upgrade the power wires on my XJ and they made very quick work of my order of 1/0 AWG cables!! 

[Minuit]

Sounds like this MJ is in good hands. We all really liked your granddad around here, and it's good to see it passed on to someone who will continue to do it justice.

[TDI_MJ_17]

Alright! It was a good day with the Comanche. Got the coolant lines for the heater core and for some of the TDI's required components, such as the oil cooler, port on the back of the head, etc. Not a HUGE accomplishment, but they are all brand new and don't have any pin holes in them, so that's a plus 
It is now running at a comfortable temperature, 186* to 210*. 

 

Just wanted to share some of my future plans for the TDI-MJ on this post before my work week starts.

Next thing i want to try and tackle would be the interior, as it is BEAT. The carpet i am able to source new from OC AutoCarpets ( https://www.ocautocarpets.com/product/1163/1986-1992-jeep-comanche-reg-cab-full-floor/ ) The Dash is in really good condition, but i would like the Cluster to be converted to the USDM version. I was considering doing the 97+ conversion for the interior, but i think with some time, money and effort i will be able to modernize the interior to make it pretty comfortable and unique. Some modernization would include a tablet style radio so i can run TorquePro to monitor that TDI, be able to run navigation, and play music as well. To complete the interior i would like to have the seat, door cards, and headliner re-upholstered, likely to be an at home project.

 Second big thing on my list would be back under the hood in the engine bay. It is not supposed to be a show truck by any means, but i would like to have some better wire management. I plan to remove most, if not all of the wiring and get it better organized and make sure the truck is not carrying any wiring that it does not need. At that point i will plan and design a new wiring harness and fuse box with CE auto electric. While in there, i will also relocate the battery to the bed and use a power block under the hood for any power needs, which that alone should really clean up the engine bay, which is really athletically pleasing but it also helps with diagnostic if ever needed. 

Last but not least for large projects would be getting the trucks dents dings and scratches taken care of and getting the truck painted. There is not much in the plans for this stage of the build yet, but not a whole lot to figure out here, just a color and single tone, or two tone, etc. 
Any color ideas that stand out to you guys that match the idea of the build? Trying to make it look like the definition of a "grandpa truck." I was thinking white would look really good, especially with a topper on it, i am looking for some other ideas as well and would love to hear from you all.

[Pete M]

if you want old-school looks with bluetooth, Minuit is adding AUX ports to the old radios and then you just need to add a bluetooth dongle to it and BAM you've got it all.    I'm rockin' a '92 XJ unit in my '06 Liberty.  

note the charging cable for my phone.  since I needed to add in a USB charger in the dash for the dongle I choose, I got a double-outlet and now I can charge while I rock out.

 

[TDI_MJ_17]

No real updates to give on the comanche. Added Boost and Pyro guages on to the A Pillar. Just been driving and loving the truck, although, can't seem to keep coolant temps at a reasonable level. for my short drives its ok, but if i need to take it on long trips, i will have to do something. i think I'm gonna redo the fan situation with a larger PWM fan set up with Arduino, and possibly a bigger XJ radiator, not sure yet. Need to study the AHU Cooling system and see what it wants and compare it to the MJ.

Only other "problem" to report is, while trying to merge into traffic, first gear has to be granny shifted, i don't know whats happening but if i try to rev it out, it falls on its face and starts missing really bad and smoking, like something is wrong with an injector and its starts sticking or something. Not sure what thats all about, so for now just granny shift it. All other gears rev out fine, even under high boost (22.3lbs according to the map sensor)  and high load. 

For now, just gonna continue driving and loving the truck!

[A-man930]

7 hours ago, TDI_MJ_17 said:

... i think I'm gonna redo the fan situation with a larger PWM fan set up with Arduino...

 

Very intrigued; please be sure to update frequently on how this goes.    

[TDI_MJ_17]

On 8/11/2020 at 8:05 AM, A-man930 said:

 

Very intrigued; please be sure to update frequently on how this goes.    

I sure will, could probably make a whole other thread on it. ill be teaching my self a lot during that, so it will be sometime before that happens.

[TDI_MJ_17]

Hey Guys, its been a while! Just wanted to share some updates for everyone who has been following along since my grandpa started the thread.
 

Towards the end of 2020 the MJ was just NOT happy with driving, AT ALL. So after some investigating and getting it towed to a place i can work on it, i began the adventure. 

 

My suspicion was that the stock head bolts didn't like hitting 30+ PSI of boost and stretched the bolts and warped the head. Tore it down and as suspected, the head had a couple thousandths variation in it, off to the machine shop you go! sorry, didnt grab a picture of the head stripped down before the machine shop!

 

 

 

 

 

Waiting on the machine shop left a couple weeks of down time, so i have been using the down time to try and tidy up the engine bay because it feels very busy. Ordered power distribution blocks, head studs and a new radiator! 

Amazon had this radiator for the 2.1l MJ listed at $180, much cheaper then what i paid for my mishimoto in the xj, and i must say i am pretty happy with it as far as quality goes, we will have to see how performance goes.

 

 

Amazon still has yet to send me the ARP head studs and wiring accesories, so until i get those i am building a fan shroud for the 16inch electric fan i run, identifying factory electrical MJ parts, planning the changes to the wiring and trying to decide if it is worth the hassle to get AN fittings and lines to move the fuel and oil filters out of the engine bay.  

 

This relay/switch had a bunch of added wires to the top post, assuming its for the starter and/or ignition.

 

 

 

 Had no idea the TDI used dual valve springs.

 

 

 

 

My 1999 XJ daily until i get the MJ back up and running haooy again

[jdog]

The wires on the relay are fuse links for various items in the jeep. The relay itself is the starter relay. The radiator looks good.

[TDI_MJ_17]

12 hours ago, jdog said:

The wires on the relay are fuse links for various items in the jeep.

There were maybe 3 other misc leads on that top post that i believe belong to the VW stuff mostly because the condition of the wires don't match. 3 looked newish and the rest looked 20ish years old 

[envirogisgirl]

Hi John, 

 

 Fellow offroader here, Its been a few years since your last post. How is the truck running? I am curious if you experienced any issues with the new motor and if you would refer the shop?  Ive a somewhat similar path with a project & am discovering that TDI engine shops are not on every corner in San Diego. Let's talk. Thanks!