To cap things off, 1997 Jeep Cherokees are completely unique wiring and engine control wise as Chrysler transitioned to the mid-cycle (on a 25 year model run) refresh, OBDII, CAN-BUS and stricter California emissions requirements. During the 1997 model year, Chrysler learned many lessons on this new wiring layout and updated it multiple times during the model year. Increased value has made Cherokees rare in junkyards, and since my 1997 Cherokee is also a Federal Emissions model, chances are extremely slim any wiring harness parts I find will match my specific hodgepodge of Chrysler fail.
Acceleration? “Do I have to?” With 190hp 240k miles ago, this Jeep can barely keep up with modern-turbocharged-10 speed transmission-everything. Angry gestures, head shakes, brake checks, and general frustration are more common than Jeep waves these days.
Where does that put me? I can rebuild this engine, throw a good cylinder head at it, stroke displacement to 4.6L and make 250-300 crank horsepower, but that still leaves the wiring problems, an aging transmission that isn’t easily rebuilt, and will make overheating even worse. Add a larger radiator you say? Currently, my XJ has a “heavy duty radiator” that requires solid motor mounts to run or the engine fan will eat the radiator. Ask me how I know. More importantly, such a motor will easily be $5,000 or more when done and when I’m done I’ll have a maxed-out Jeep I6 that will not be as reliable as the original OEM engine.
That leaves us with swapping to the ubiquitous “LS” or Gen III small block family of engines. Horsepower, fuel efficiency, compact dimensions and unrivaled aftermarket support make it a no-brainer for me. The Jeep 4.0L with all accessories measures a woefully inefficient 24” wide and 31” long, compared to the 24-25” width by 27-28” length (depending on accessories) for most Gen III small blocks. Cooling will still be an issue, but modern cooling management, aluminum cylinder heads, and the 3-4” gain in clearance at the front of the engine will mean I can fit a lot more fan and radiator in the nose. Weight gain? It appears that swapping to an iron block truck engine will net 20lbs in weight savings over the all-iron Jeep 4.0L. Horsepower will obviously be improved and Junkyard donors are hard to miss if you throw a rock.
Little Sluice, Rubicon Trail