1993 Grand Cherokee Diesel Conversion
With raising gas prices we have decided to convert our family Jeep to Diesel power. Over the next few weeks we will remove the gas power system and start installing the diesel system. I will try to keep this site up to date as the conversion progresses.
To date we have adapted the diesel engine to a Jeep 5 speed transmission which will replace to original automatic tranny.
The engine of choice is a new Isuzu 4JB1-TC, 2.8L turbo-charged and inter-cooled 4 cylinder
The picture above shows the original engine and the picture below shows the new diesel bolted to the Jeep AX15 tranny, red spacer is the adapter.
With the old straight six removed there is quite a large hole left. Once fitting of the Isuzu diesel starts that large hole gets too small very quickly!
The first issue is the motor sits way to far back under the cowl. This was fine for the six but most of the four disappears under there. We moved the tranny / transfer case forward by 3 1/2" which gave more access to the engine. The Isuzu oil pan had a big sump protruding from the drivers side which interfered with the front diff, we removed it and now have no clearance problems with the pan.
Installed the Isuzu "industrial" exhaust manifold to get better turbo clearance with the firewall but the mounting flange was at a different angle than the one we removed so a wedge was built to correct it.
Motor mounts were a challenge as always but after a few tries we got it right, I think.
Looks like the original Isuzu rad, A/C condenser and inter cooler will all bolt together and drop into the Jeep as a single unit once we fabricate mounts.
It's been a few weeks since we updated the web site and quite a bit has happened. Another rebuild of the motors mounts and I'm finally happy with them. I think we have all the major components installed or at least a location figured out. I don't think I would have attempted this if I had known up front what was going to be involved, it would have been much easier to convert to electric power than Diesel. :)
To date, a couple of months, not a few weeks! we have made the following modifications:
- Shortened the front drive shaft 3"
- Lengthened the rear drive shaft 3"
- Adapted a 5 speed standard transmission to a vehicle that was originally an automatic
- Re-bent shifter to clear dash
- Removed the fuel pump from the gas tank and installed a pickup tube
- Fabricated new engine mounts
- New radiator mounts
- Modified the oil pan
- Added lead sound shield to the firewall
- New air conditioning hoses
- Trying to have a new power steering hose made Jeep / Isuzu
- New exhaust
- New throttle cable
- And the saga continues...
Nov 22, 2003
Finally on the road, awesome vehicle to drive. Lots of power and great fuel economy, about 35 mpg (imperial) which give the Jeep about a 1000km range per tank!! Noise was a problem (for a family vehicle) at first but we added a little most sound shielding to the transmission tunnel and are working on an air box to quiet en the intake noise, these two efforts have made a huge difference to the interior sound level. Used a Jeep V8 muffler and tail pipe with a custom built header pipe all in 2 1/4" which gives low back pressure and very quiet exhaust. :(
A few tricks to fool the Jeep computer so all the original sensors would work and I still have the tack to deal with which will require a sensor mounted onto the front crank pulley. I'm also adding a 1 3/4" suspension lift kit to give a little more oil pan clearance for better off roading.
Four months without lifting the hood, other than to show off the engine. I get lots of email from people wanting to do similar conversions, unfortunately I don't do this for a living and don't have access to more engines. I did not keep patterns or parts lists, this was just a one time conversion for myself. It took way more time (they always do) than I had hoped and way more involved. I would not recommend anyone attempting this unless they have lots of mechanical and electrical experience. The engine came out of a 2000 Isuzu NKR truck that we converted to electric drive, I know a similar engine is available from Isuzu Industrial engines for about $6Kus. The VW Diesel may be a good swap or the best solution may be to import used engines from Europe where the diesel came in the Grand's. If you do a conversion please send me some info and picture as its interesting to see what other fools are doing! ;>)
Still cruising along. Averaging about 1200 km per tank of fuel (70L tank).
We love our Diesel Jeep and now our Diesel Dodge Dakota