Finally I finished installing diesel into my 1981 cj7. I sticked with VM 2.5 turbodiesel engine installed in Cherokees in 90s. VM is an italian engine maker. Their engines were installed to some European models starting from early 90s including Rover Defender, Opel, Chrysler Voyager, Alfa Romeo, and Ford Scorpio. This engine is, unfortunately, not available in the US. Maybe Canada. The instalation is straighforward and easy. The engine looks original in the engine bay. I am going to write more about the conversion.
I have played with the diesel idea since 2006 when I saw bt4 swaps on many forums. However, I wanted a better engine, with hp rating and weight comparable at least with early 258s. Secondary goal was to use dana 300. Decided for ax15 as this turned out reliable enough and not pricy as nv4500, and could be easily mated to dana300. To mate ax15 with a diesel engine gave me several choices.
MB 300 td (1981-1985). This is engine discussed on many forums, it is a quality engine, the clutch has correct 10-spline input shaft. However it has just smaller 240mm diameter. Parts are rare and very expensive, and these cars are hard to get too.
Ford Transit 2.5 d. This has correct 10-spline shaft and 267mm clutch (same as jeep). However this motor is just too lazy and nearly impossible to find in good condition.
Iveco 2.8 td. This is another suitable engine with correct flywheel that would accept jeep clutch (must be redrilled). There is about 1/2" space for a custom adapter between ax15 bellhousing and engine block. However these engines are too pricy and high mileage (used on cargo vans) so i stepped back.
Fiat Croma 2.5td. I met a guy on a offroad meeting who had this engine in his jeep. Just saw it from outside, but it was after I got the VM.
As opposed, Jeep Cherokees 2.5td are cheap because these engines have problems with cooling. Assembled in Austria, they have tiny radiators that simply do not keep up with the heat. Furthermore, there are 4 separate heads that tend to crack if overheated (Chrysler improved the casting in 2001). However, they should not overheat in CJ7, because CJ7 radiator is twice as big as the one in cherokee. I got mine in the UK, and drove it over 1 200 miles right after start. The guy parked it in his backyard I would say for months, it started right away and have not had any problems. The sound is very strong; amc258 sounds like a tiny motor from a passenger car.
118 hp (88 kW) @ 4000 rpm (amc258 has 112 hp @ 3200 rpm)
221 ft.lbs (300 N m) @ 2000 rpm (amc258 has 210 ft.lbs @ 2000 rpm)
Size and weight comparable to 151
Bosch rotary pump
1994-early 1995 are fully mechanical controls.Needs just 12v for starter and fuel valve solenoid.
mid 1995-1996 got a simple engine controller (SBEC) and a few sensors (1st injector, temp, speed, CPS) that delays fuel pump timing. This is the engine I have.
1996 on - electronic, fly-by-wire control. Has potentiometer at gas pedal.
The implementation in CJ7 included following 12 steps:
1. Custom motor and transmission mounts. See photos. All mounts are mounted in the stock openings.
2. Modification of header, relocation of muffler to the passenger side, moving gas tank to the driver side. I decided to route the exhaust pipe on the passenger side (where turbo is). There s limited space due to dana 300.
3. Cooling system piping, instalation of coolant expansion tank. It is best to use 38 mm ID flexible hose. CJ hoses are too short. I used coolant tank which I had available. There are definitely better shapes.
4. Intercooler frame, and piping. Piping turned out more problematic than I thought. Four 50 mm elbows, two 50 to 58 mm reductions, and about 1m of 50 mm pipe are nice to have, can be bought at ebay, due to being way too pricy (e.g. 1 elbow 20 US$ imported from china) I used hoses off XJ.
5. New oil tank. Due to the front dif being on passenger side it will hit the VM oil tank. Custom oil tank is thus needed, or dry sump.
6. Steering pump. Steering pump hoses and holenders from CJ steering box fit the VM pump.
7. Voltage regulator. Custom voltage regulator is needed, because VM has PCM-built regulator and CJ has built-in regulator in the alternator. Any regulator that grounds or give +12v to the field should be OK; so far CJ had no charging problems.
8. Injection pump timing control. The pump does not have any choke. It has timing solenoid that PCM turns on and off depending on signal from 1st jet sensor, temp sensor, and CPS. Post the schematics later.
9. Sensors (coolant temp, oil pressure), wiring. I used CJ sensor for CJ gauges.
10. Fuel filter and fuel piping, fuel heater and glow plugs wiring. I placed fuel filter next to the wiring harness on the dashboard.
11. Adapting dana300 to ax15
12. Driveshaft adjustments
Yeah from what i have heard vm is a likely candidate if they ever make a diesel wrangler for the American market. I would think that is a good choice but i have very little knowledge of diesels.
You'll have to give us some picture and some of your numbers. Hp, torque, mpg's, I am interested in how they compare to the 258. Also interested in how difficult it was to put in and how expensive it was to get that engine.
Disregard everything i say
I have a dana 30 front axle and amc 20 rear if anyone is looking. Both are 3.54, drums, narrowtrack.
I'd like to see this on paper. I think the newer CRD's would be very expensive to get a hold of and they are pretty limited quantity wise compared to other motors. Something you want to definitely consider is availability of the motor itself - the price of parts and anything else will depend on that. That's kinda why Chevy motors seem to be the big thing to swap into Jeeps.
I've looked into the 4BT swap, but financially it's not really worth it for my uses right now. (I may do propane still though, lol). Some day I'll venture into this world when I have nothing better to do with my time and money haha.
I have played with the diesel idea since 2006 when I saw bt4 swaps on many forums. However, I wanted a better engine, with hp rating and weight comparable at least with early 258s. This gave me several candidate engines.
MB 617 300 td
Ford Transit 2.5 d
Iveco 2.8 td
Fiat Croma 2.5td
To be continued...
Curious... Did you rule out the SD-33 that was actually used in CJ's in the US for any particular reason?
The VM engines have a very very very bad reputation here in Europe. I donít know of any owner with a car with a VM engine who hasnít had BIG and EXPENSIVE problems with it.
The VM engine here (Spain) is a big no-no.
Just a little google search will help you...there are dozens and dozens of frustrated and irritated owners with this engine...but perhaps as you say the VM with the CJ7 radiator don't cause BIG problems...personally, I will not try if this is true in our car.
don't bother with the 2.5 VM unit its a nightmare of an engine, the cylinder heads become porous and crack and they cost mega bucks to repair, many a good diesel cherokee is written off over here down to problems with the engine, the other problem with it is it hardly gives any better mpg than a 4.0 litre fitted to the petrol cherokees,
Your better bet is to go for a daihatsu Fourtak 2.8 turbo diesel ( not sure they are called the same over there)
I know of one cj7 with this conversion and it has proved very reliable and very capable at running with larger rims and still returning 30mpg (uk)
I don't know how many of you have ever seen diesel cherokee, have experience with its engine repairs or your knowledge comes from googling. As I said cherokee has poorly designed cooling system. That there are many with written off engine? What should it mean - that someone mechanically skillful will burn this engine like probably did Joe Redneck who has no idea what's under the hood?