Better Performance Jeep 2.5TD VM Diesel Engine

I've had a number of messages about the mods i've made to the Jeep Cherokee XJ and its 2.5 VM Motori 425 OHV Diesel Engine to get more power from the engine. First off I am no expert at all but I the pursuit of turd polishing and getting more out of something from its original state.
The 2.5 VM has a terrible reputation amongst some and its loved by others. Its cylinder heads were a nice idea but in practice a one piece head would have been better, but better heads are on the market and the engine can be reliable and perform very well with modifications.
I decided to keep my VM and not swap it out to see what I could do to make it more of the engine I wanted it to be.
In this video I discuss the avenues you can take to get more power from your VM without compromising the mechanical functionality of the engine.
Thanks for following this build and watching and please find the build components below -
/ @workshoptowilderness
Support me on Patreon - / workshoptowilderness
My Amazon Affiliate Store - www.amazon.com...
Follow me on Instagram - / workshopwildernessadve...
Follow me on Facebook - / workshop-wilderness-ad...
Full VM Build Playlist - • The Factory Diesel JEE...
Build Components -
Turbo Materials:
GT2052 (727264-5001S) - www.speeding.n...
Oil Feed - M10x1.0 to 1/8 npt -www.streetperf...
T25 Gaskets (x2) - www.speeding.n...
T25 Turbo Heat Cover - www.speeding.n...
Universal Oil Feed Line - www.ebay.co.uk...
Intercooler Materials:
Universal 2" Intercooler Pipe Kit - www.ebay.co.uk...
Universal One Sided Intercooler - www.ebay.co.uk...
Gauges:
EGT Gauge - www.ebay.co.uk...
Boost Gauge - www.speeding.n...
You will have to source a 1/8npt to 1/8npt Boost line -
Manifold Extension Build Materials:
Manifold Extension Pipe 90 degree (x4) - www.j-spec.se/...
Manifold Extension Pipe Straight x1 - www.j-spec.se/...
T25 Stainless Flange (x2) - www.speeding.n...
Exhaust Wrap - www.j-spec.se/...
Intake Materials:
2" to 3" intake adapter - www.j-spec.se/...
3" aluminium 90 degree bend - www.j-spec.se/...
3" Silicone Coupling for Air Box - www.j-spec.se/...
Universal; Air Intake CLOSED - www.ebay.co.uk...
You will need to find a suitable air intake system as there are many types.
Stainless Exhaust Materials:
2.5" Flexi - www.j-spec.se/...
2.5" 90 degree x1 - www.j-spec.se/...
2.5" Straight - x2 www.j-spec.se/...
2.5" 45 degrees x1 - www.j-spec.se/...
Some materials will require sourcing at the time of construction but this is the basis of the downpipe and the first parts of the exhaust up to the silencer.

[@mrfixit____3651]

I’m a fan of just about anything that has to do with an XJ and polishing TURDS. These 2 things go hand in hand. Also, I’m jealous of your diesel options that we don’t get in America.

[@g-walley-racing8976]

Manifolds and turbo from a zj is a bolt on swap for a lefthand drive, i bought a zj for parts and did this after watching you build yours. Got the mechanical fuel pump from it aswell, very good videos mike. Cherrs from norway

[@jonathanweston2448]

What a tremendously informative video - one that the web has been missing out on for quite some time I feel. Superb!! Well done and thankyou very much!

[@WorkshoptoWilderness]

I've had a number of messages about the mods i've made to the Jeep Cherokee XJ and its 2.5 VM Motori 425 OHV Diesel Engine to get more power from the engine. First off I am no expert at all but I the pursuit of turd polishing and getting more out of something from its original state. The 2.5 VM has a terrible reputation amongst some and its loved by others. Its cylinder heads were a nice idea but in practice a one piece head would have been better, but better heads are on the market and the engine can be reliable and perform very well with modifications. I decided to keep my VM and not swap it out to see what I could do to make it more of the engine I wanted it to be. In this video I discuss the avenues you can take to get more power from your VM without compromising the mechanical functionality of the engine. Sorry about the volume of the engine at 20:58, I messed it up. I'm just saying that I've ran the AMC heads for quite a while and they have been great.

[@efi4tuning]

Hi. My english is not really good. So i would appreciate part list written. Exhaust and intake manifold from other vehicule is ? Tks

[@jamesa7506]

A fine video overview of your awesome jeep my friend! Tinkering with anything you enjoy will always be a labor of love, a diamond in the rough rather than polishing a turd. A great 4x4, an amazing family, and loads of skills, I'd say you're winning the game Mike!

[@Useaname]

I've got a Chrysler Voyager with a 2.5l Motori diesel crd engine. It's great. Never let me down. And very fast considering the weight of the vehicle.

[@051biohaz]

Another great video, Mike…you are a big inspiration to me with the project Jeep, and the old school bushcraft stuff too…finally got my axe shaving sharp and now I’ve gotta build a Jeep..lol. Thanks for the uploads over the years..:)

[@jonathanweston2448]

This should be interesting, I’m half way through building a 2013 M57 engine for my XJ 60th.

[@Robdutton91]

That’s a swap I really wanted to do with mine… then I sold it. Good luck and stick some videos on KZbin when it’s done

[@jonathanweston2448]

Absolutely - I’ve already got the bellhousing mounts and flywheel adaptor, I just need to get the engine mounts made. After that… it’s a case of getting the wiring looms modified to suit each other. Hoping to have it completed by about November, now that I have my JK on the road instead.

[@Robdutton91]

@@jonathanweston2448 take it you’re adapting an AX15 to fit it? And have you got the Jeep flywheel adapted to the BMW crank then?

[@joaoboia7837]

Hi Mike, I sold my 2.5tdi Jeep ZJ but still have a spare blown engine I bought for 200Eu.. and lots of spares , also have the mechanical fuelpump in a box.I still have my 3.1TD WJ , I blew cylinder no. 5 linner on the highway when pushing for the engine. Had do rebuild it and is working fine. Also rebuilt injectors , you can also make a poptester for the injectors with a handpump and gage, and tune them. Like you videos. Regards

[@Robdutton91]

I would love to see you dyno your Jeep just so we all know how much power and torque it’s making with all that turd polishing 😅

[@cowboy6591]

I'm running a Cummings diesel in a Dodge pickup truck. Single turbo charged and opted to NOT change anything as to prolong the life span of my rig. When left as stock, Some motors are hitting a million miles. I see 20-somethings hop up this motor to 400 hp and before one summer is over they BLOW the engine half way through the hood. These diesels are too expensive to die young, so I leave my truck stock.

[@WorkshoptoWilderness]

There is certainly a limit to power on these old engines. keeping them stock will certainly prolong the life in most cases. I know many people with over 500k on these engines and there still running fine. Regular oil changes seem to be the key. I use a bit of engine restorer in mine with every change. Mine isnt stock to be fair. From factory it was 116hp and 300nm. Now its around 150hp and 380nm. Its not crazy power but its a nice improvement without getting silly with it.

[@givememountains]

Hey Mike! My family has a 2000 xj very similar to yours and we run electric blankets off our power station and it barely pulls any amps at all. Works great and keeps us warm when it’s cold! I would try that next time you’re out!

[@WorkshoptoWilderness]

Ah fantastic, that sounds amazing. I will try and find something online! Thanks for watching

[@givememountains]

@@WorkshoptoWilderness we also run them on each seat inside to give us heated seats in the winter! Works fantastic for us :)

[@WieDrDerJonge]

I have the same engine in my Opel Vauxhall Frontera. I have converted mine to a mechanical pump and a VNT turbo from a Volkswagen LT 2.8tdi. This summer I will upgrade the pump to a 11mm rotor head and a GTD1752VRK turbo which spools at 1400 rpm and is capable of 200+ Hp.

[@WorkshoptoWilderness]

Sounds really cool. I've put the semi mechanical pump in mine with a gt2052v. A few alterations to the manifolds. Its running really nice, good power and stable combustion temps under load. Do you think your engine will survive at that power level? Mines probably around 140hp (I can't be exactly sure) and combustion temps can get pretty dam high. I guess it depends on what you use it for. I also run the pump on full advance

[@WieDrDerJonge]

@@WorkshoptoWilderness Should be ok with this powerlevel. Everything is pretty big and heavy on a VM like M14 headbolts and such. It is my daily driver so the times I will go full throttle will be not many times and only for short distances. I also let it warm up really good before I go full throttle. On the new setup I have the EGT in the manifold before the turbo but in my current one it is right after the turbo. On full throttle it only shows like 450°c. On my new setup I'm going to run a timing spacer on the pump for more advance on higher rpm.

[@WieDrDerJonge]

@@WorkshoptoWilderness I have the Frontera currently on the dyno at work so I will let you know what power it makes.

[@WorkshoptoWilderness]

@@WieDrDerJonge Sounds awesome, I would love to see what it can do on the dyno. I contacted ARP at one stage to get them to make some studs for the heads. I never went through with it because of the price. IM sure it will great when its done.

[@WieDrDerJonge]

@@WorkshoptoWilderness I looked into M14 head studs and it seems some Ford V8 diesel uses them but I never digged into it that much because M14 is already big for a small 2.5l diesel.

[@rickz9495]

I dont know how your pump can be tuned. But most 200/300tdi land rover guys just fidle with the boost diaphragm/fuel pin. To change how fast the fuel increases with boost and how much it increases. Easy to do and easy to reverse. And no parts needed. They usually leave the main fuel screw alone because it does not need more fuel at idle or very low throtle input. Edit: and for the Bosch pumps you can get a timing spacer that allows more dynamic/total timing advance in the pump. Wich should increase higher rpm performance without messing with the base timing of the pump.

[@WorkshoptoWilderness]

Its exactly the same on the pump I have. It's a manual Bocsh pump with a boost diaphragm and fuel pin. I've just tuned it up so it responds the boost better making it all kick in faster.

[@rickz9495]

@@WorkshoptoWilderness sweet! Plenty of info to be found on tuning Bosch ve pumps. You might want to look in to a timing spacer. Apparently more timing at higher rpm reduces egt's and allows for a litle bit more fuel. And they are cheap. But if you are happy with the way it drives now dont touch it lol.

[@WorkshoptoWilderness]

I've watched lots of videos and there seems to be some great information out there which has helped me a ton. I've advanced the timing of the pump to full advance and disabled the retarding solenoid so it remains at full advance all the time. It's been running great and it seems to have contributed to a bit more power and better fuel economy which makes sense. I have noticed a slightly higher egt though which confused me but I guess I'm running higher compression now? I haven't seen those timing spacers but I don't know if I should keep playing with it lol. This old VM is probably working harder than normal

[@mcplutt]

I have never heard of steel or iron pistons. But there are forged, cast and different aluminium piston types out there.

[@deckydonnelly5299]

Hi Mike. Great video. Just back from a 2,500mile camping trip around Europe and the Alps on my Mk1 2.5 TD VM Cherokee. It performed faultlessly, only getting warm on the prolonged hill climbs. Please can you point me in the direction of the tuning of the mechanical fuel pump to reduce turbo lag? Mine seems to come in about 2,000rpm but would love this to be a little lower. Otherwise I'm just going to maintain it and chase reliability rather than power. Much appreciated.

[@WorkshoptoWilderness]

Ah nice, sounds like a fantastic trip. Nice to hear an old diesel cherokee is still going strong. I could make a video but far better ones exist - kzbin.info/www/bejne/fJeypH2Hbb2Lq8k hopefully this will help, it helped me tune mine.

[@4CarbideGaming]

Man i was just wondering what had happened to your Bush craft channel the other day. I enjoyed those videos. While looking up a similar diesel engine i stumbled onto this channel. Is your other channel still up. Or are those vids still available.

[@WorkshoptoWilderness]

The bushcraft channel is still up and all the videos are still there. I just left it due to a number of things that changed and went wrong with it. But its a long story!

[@gunterweniger8019]

With the "MK2" Scorpio making 125 hp (factory rating..) and the "MK1" Scorpio doing 116hp (factory data sheet) How does that go with the saying in the Video that the turbo on MK2 is the limiting factor? The Scorpio MK2 .. the one with the 🐸 face, this Ford has Bosch Diesel system (EDC) mostly notable by the wire on first cylinder injector and by the Elektrik module on the pump body .. But what's different there actually on the engine and fuel supply as such, to achieve the around 10 hp gain coming from the earlier 2.5L VM Italy. Is the injector size identical...is the capacity of the injection pump identical??

[@WorkshoptoWilderness]

All I I know as facts are the waste gates open at different pressures and the earlier turbo makes more boost on paper and with testing. There was also a significant difference in power on my jeep and also spool up (which isn't power technically but response) after fitting it. I dont know much about the Scorpio but didn't the mk2 have the 3rd generation vm with the balanced crank shaft and manifold pressure sensor? That would probably explain more power. The jeeps never used that variant I don't think. At least I never found one. It seems pretty easy to squeeze more power out of them although not too much of course. I use a GT2052 at around 25psi along with a slightly modified ve pump that I've partially advanced coupled with a different fuel pin and the jeep feels like its around 150hp. Another guy has done something similar and it dynoed at 158hp. He's swapping the pump plunger to 11mm which he thinks will allow much more power, although he doesn't think it will be stable. I'm happy with mine where it is I think. But back to what your saying, perhaps the Scorpio saw some slight changes in the ecu that the jeeps didn't. Given that are electronically adjusted for timing at that stage and the MAP might have some influence on boost and fuel delivery

[@ViktorSuhov]

Does the exhaust manifold need to be removed periodically and cleaned? Or does the soot just burn down by itself due to high compression and temperature in a diesel engine?

[@WorkshoptoWilderness]

No it just burns up unless you drive around town really slow and the engine doesn't warm up.

[@thescousecyclist917]

Can you rebuild the number 1 injector on these as they can get quite expensive and seems to be a common problem on this engine, I had to replace mine about 2 years ago with one from a Vauxhall frontera and I noticed some power loss maybe it’s just in my head I don’t have any data to confirm but definitely feels sluggish (98 mk2)

[@WorkshoptoWilderness]

Yeah they fail and then the ecu goes into limp mode restricting fuel to stop turbo spool up making the jeep gutless in an attempt to protect it from damage. I deleted my numbed one injector, maf and ecu by installing a manual fuel pump. I now just use a normal injector and manually time the engine to 2 degrees advanced

[@Jack-tx2ve]

Mike, I love the channel. I am an engineer on steel boats. I have owned Jeep XJ's for 7 years. Mine is a 1996 prefacelift 4.0 from Japan. I have just purchased another 2.5td 1996. I own other vehicles but the XJ is the best all round vehicle I have ever owned. Did you know there is a 6 cylinder version of the VM engine? I have noticed you sound like you have a bit of a westcountry accent? Were you a fellow carrot cruncher before the move to Sweden?

[@WorkshoptoWilderness]

Hey Jack, thanks for watching. I'm originally from the Wotton-under-edge area of South Gloucestershire so I was indeed a fellow carrot cruncher. I had no idea there was 6 cylinder version of the VM. I saw the 5 Cylinder in the ZJ. Congrats on the Jeeps by the way, nice to hear that they have a good home. so many get scrapped now, its kind of sad. I wonder if that 6 cyl could fit in the XJ haha, perhaps not. Is it a marine application with fresh water cooling?

[@Jack-tx2ve]

@@WorkshoptoWilderness I have just finished a job on a boat for a chap from wotton under edge, small world. The 6 cylinder vm was used as a boat engine and a stationary engine. They were also marketed as a detroit diesel. I have seen one in a range rover classic, I can't see why they could not be made to fit an XJ. They sound great. Detroit 638 is the 6 cylinder vm unit. 160hp as standard.

[@orgonomix]

@@Jack-tx2ve Mercruiser 642 as well, that's what I dream of putting in mine .

[@pieterhoffman1514]

I have notice you have not the nock censer Injection on your engine. How did you gat rid of it. I have a 1998 Grand with the 2.5 motor. I am planning to use the 2001 3 L intercooler.

[@WorkshoptoWilderness]

Once I swapped the pump and advanced the timing I pulled the sensor injector and replaced it with a standard injector to stop it retarding the timing so that the engine runs on advanced timing

[@000jamesh]

Hi, thanks for this explanations and videos, I’m not mechanical too and enjoy work on my Jeep, I’m here too to ask your opinion about EGR, I had been here trying to understand if I should erase my EGR or not, I like keep things that comes original in car but I’m still inquiring about this and duno if keep it or erase it . Congratulations, you did an amazing work whit your car 💪

[@WorkshoptoWilderness]

Deleting the EGR is normally done for engine health. First off the negatives are the slightly higher combustion temps because recirculating the exhaust gas will drop them slightly. This isnt really an issue on this engine in reality but you would delete it to stop suit building up on the intake manifold and cylinders. Personally Its beneficial to the engine but not to the environment. Thanks for watching and for the comment.

[@000jamesh]

@@WorkshoptoWilderness

[@000jamesh]

I undestand that , and usually people say that its bad to the engine, however still remains in me some questions about erase EGR...the engine was design to funcion whit that and im not sure if erased will be funcion in the same way . Sorry about all this , people are diferent and some people like to improve things and i dont see any harm in that , in fact i honor that , but i like to trie undestand the things very carefull before act and i would like to have more power in my car ofcorse , but i still have afraid of erase this....thats why i asked your opinion. Thanks again, your work there is impressive ...really

[@tomcat1557]

I feel ya regarding the turd polishing Mike! Live for it though. Mate, im keen to add a better intercooler to mine but i dont want to lose my a/c because it hot over here in NZ. Have you got any ideas for this? Cheers, Tom

[@WorkshoptoWilderness]

You can fit the cooler and the ac in there. A friend of mine has ac and has done it. The clearance is tight but if you find a thin cooler it will work better.

[@duketyler37]

Do you have a place that I can get a motor? Looking to swapping from gas to diesel.

[@WorkshoptoWilderness]

A whole motor? Do you want this one? What is the engine and transmission in your XJ at the moment?

[@adrianll8289]

Does the scorpio intake manifold fit with the OEM turbo and exhaust manifold?

[@WorkshoptoWilderness]

Yeah it will bolt straight on with the standard exhaust manifold below it.

[@danparsons798]

How did you get the fuel consumption so good

[@alllyy1568]

🚨URGENT🚨hello! I live in Turkey. my tool; (Alfa Romeo 155 2.5 TD VM engine) The electric fuel pump failed and we applied a mechanical pump with a volume of 1.9, but we could not get efficiency!!! Can we get efficiency if we apply a voyager 2.5 vm diesel mechanical fuel pump?? And what settings should we make? Your advice is very important to us*

[@WorkshoptoWilderness]

Hey. A chrysler voyager pump from a 2.5 vm engine 425ohv will work on your alfa romeo. I have a video on installing the pump - kzbin.info/www/bejne/f6XUnYCuetKfaKs The engine manual is also in the description on this video. Installing the pump isn't that difficult but you would need to adjust the pump timing using a dial reader.

[@alllyy1568]

@@WorkshoptoWilderness What difference did you experience with the new pump assembly?? Is there an increase or decrease in performance? Also, I don't know how to set the timing, I will have the service watch your video.

[@WorkshoptoWilderness]

I got an increase in performance but I tuned the pump to almost full advance. I also tuned the pump and fuel pin so that the turbo comes in earlier. This makes the turbo come in at about 1400rpm and peak out at 2500rpm at around 19psi. Its a gt2052 so it spools fast and you can turn the lga ontop of the pump so that the pump and turbo work together better. You can't make the injectors give more fuel without changing the volume or nozzles but you can get better turbo responsive, more power from advanced timing and better atomisation of existing fuel

[@alllyy1568]

@@WorkshoptoWilderness Hello there! i asked you a question before I found and bought a mechanical fuel pump for my vehicle with engine code 425 (2.5 Voyager diesel pump). But I still have questions for you. *Is your RPM clock running? if it works how? *Does your vehicle stall at sudden accelerations? *How did you make the fuel pump settings? *Did you make a connection from the turbo to the fuel pump? * Have you made the injector settings? And finally, what kind of settings did you make during this whole process? I left my vehicle at the service, what should the vehicle master follow? Thanks..

[@Calledspring]

Hello Do you have a spare pcv hose from rocker cover to the pcv valve? Or a know how to get it?

[@WorkshoptoWilderness]

Sadly not. You can make something up with two bends a straight length and two plastic hose connectors perhaps

[@ohrealy1]

The oil pressure sensor on my 2.5 VM diesel is scary to look at ( when i eventually found it) i think they moved it around a bit during production of these engines mines on the opposite side to the turbo. Anyway has anyone changed one because where it is and how hard it is to get at the more information about them i get before i tackle it the better cheers.

[@WorkshoptoWilderness]

I removed mine because it broke and I couldn't find the original part so I fitted a analog line with a gauge to the dashboard. You have to remove quite bit to get access. I think I took off the manifolds and such but I was doing other jobs at the time so I cant quite remember if its accessible without doing that.

[@ohrealy1]

@@WorkshoptoWilderness mines broke not sure if it's a connection issue or the actual sensor. I've seen them in a few locations on the VM engine the one on mines on the opposite side of the engine to the manifolds. It's the weirdest looking unit I've ever seen it looks like a push fit connection not that I've ever seen a push fit oil pressure sensor. On the upside it's threaded into the block so I should be able to sort it out.

[@sebastiandiesel9248]

Where did you find the injectors rebuilt kit?

[@WorkshoptoWilderness]

Its more just the nozzles I replaced - www.ebay.co.uk/itm/270948680530

[@jmen593]

Hello, does this engine use wet liners or dry liners in the cylinders?

[@WorkshoptoWilderness]

Wet liners.

[@jmen593]

@@WorkshoptoWilderness Thanks! Let's see if you can help me with a technical question. I'm installing new cylinder heads (Cherokee xj 2.5vm 2001), and I noticed that one of the cylinder liner is not entirely aligned with the block's flatness. It's off by three hundredths of a millimeter. Do you think I need to resurface the block?"

[@WorkshoptoWilderness]

@@jmen593 The manual states that 0.01 - 0.06 mm of liner protrusion is within normal range. The manual is here page 36 - dokumen.tips/documents/vm-25-manual.html?page=36 I'm not sure if you have it or not so I put a link.

[@jmen593]

@@WorkshoptoWilderness Oh, I thank you very much, you are a true professional!

[@WorkshoptoWilderness]

@@jmen593 I don't like to guess so I took a look haha. The individual heads come in handy sometimes for variations like this.

[@theradoful]

30 MPG??? wow I drive an almost stock XJ and only get 20 MPG. Maybe you have some advice for me on what I can check to get better efficiency

[@WorkshoptoWilderness]

Is it a 4.0 or diesel? A stock diesel should get around 35mpg sometimes more. Mine is obviously obese so it's around 23 at best.

[@theradoful]

@@WorkshoptoWilderness it's the VM, with the electronic injection pump and without the egr

[@WorkshoptoWilderness]

@@theradoful 20mpg from a stock VM is quite surprising. I would test your injectors to start with. You can run them through a manual injector cleaner press, or just get them rebuilt at a shop. The MAF Sensor also might be an issue but I doubt it.

[@baashie]

Someone correct me if I'm wrong: 72L of fuel used on 650km trip is about 21mpg. Not 30mpg

[@WorkshoptoWilderness]

I knew I was off with the mpg measurements but yeah around 1 in 11

[@johnoak4933]

xj tanks are a tricky thing, cause its hard to properly top off so you never have the same amount of "max fuel" so could be the first time you fill in 72L an think you toped of just cause the fuel pump gun cliks, next time you go in and rock the jeep a bit or fill slower and you get 75/76 if you stay long enough you can even go up to 90/95 so its hard to have an accurate estimation that way

[@Ijusthopeitsquick]

I calculate it as 25.7 mpg (UK gallons).

[@Robdutton91]

@@Ijusthopeitsquick sounds more like it. My 4.0 manual used to get 20-22mpg. There’s absolutely no way a diesel with just over half the displacement is getting worse than that 😂

[@Ijusthopeitsquick]

@@Robdutton91 My dad's 4.0 automatic was anywhere from 17 to 23 mpg (UK). Mike's vehicle has a big lift and huge tyres and a lot of extra weight, so mid twenties sounds about right.

[@gcnature]

Why do you still buy parts from ebay in the uk ? Is that because taxes are not applied to you being a britiish laplander :D ? Or because your jeep is a left hand drive ?

[@WorkshoptoWilderness]

I buy parts from everywhere but the injector nozzles were from Germany. I get taxed even more when I buy from the uk because of brexit

[@TaralgaBushAdventure]

Say nozzle...one. more. time.

[@WorkshoptoWilderness]

😅 do I sound like a twat

[@TaralgaBushAdventure]

Ha, no Mike, just a very English pronunciation :-) Its actually a great video, where the underlying story is more about - whatever your 4x4 is, there's things to work on for more power, but that rabbit hole can get deep.