The '05 Liberty recently got our attention with a new engine, the first diesel in a small SUV in North America. Many of us run diesels-though not this small-and we were interested in getting a feel for one of the new common rail diesel (CRD) motors. The Liberty, which competes with other small SUVs like Toyota's RAV4 and Honda's CRV, has a lot to offer, and the CRD definitely makes it better.
The engine-four cylinders and 2,768 cc's of snarling diesel-is made in Italy by VM Motori, which is owned in part by Detroit Diesel. The 2.8L uses an advanced common rail direct injection fuel system, which Jeep says is more efficient than a pre-chamber indirect injection configuration. The injection system requires fuel delivery pressures almost 70 percent higher than normal distributor pumps can supply. The pump is driven by a cog belt off the camshaft to deliver fuel at close to 24,000 psi. To do their job, injectors on the new CRD Diesels have to be manufactured to even more precise standards, allowing fuel to burn more completely. The result is a lot less smoke, better mileage, and better power.
There is no delay in starting the motor in the morning. Electronically controlled ceramic "smart" glow plugs can warm up in only two seconds and glow only when needed. Another upgrade is the use of an electronically controlled, variable-geometry turbocharger. The turbocharger has moveable vanes that allow the turbo to quickly spool up and also deliver larger air volumes as the rpm increases. Turbo lag is minimized, and top end power is maximized.
To smooth combustion and quiet the engine at idle, two pilot injections are used prior to the main injection. Balance shafts, a new engine cover, and a torque converter turbine damper have also been developed to help combat noise and vibration. New engine mounts, called hydro mounts, contain fluid that helps isolate the engine vibrations, and additional noise-absorbing carpets and liners are present in the engine compartment and cabin.
There is no doubt the 2.8L CRD is one sweet little motor. It may not be as quiet as the Touareg diesel, but it does not rattle at idle, and it is practically smoke-free. It makes V-6 horsepower (160 at 3,800 rpm) and V-8 torque (295 lb-ft at 1,800 rpm), and gets four-cylinder mileage. We averaged 20.98 mpg, with a low of 19.2 mpg during off-highway use. We got 23.5 mpg cruising at highway speeds, where the Liberty was most at home, loping along at 70 mph with 2,000 rpm on the tachometer. The turbo allows the motor to remain largely unaffected by altitude, which was not the case for all our 4x4s as we flogged our way up 8,000-foot passes, and later 10,000-foot peaks.As you might expect, the Liberty is also quite maneuverable.
The Liberty has a great little engine and a real Jeep look, but alas, its actual off-road capability is limited by two factors. First is ground clearance, which at 6.4 inches to the front skidplate means the driver of the Liberty is treated to a symphony of bangs and clangs, even on the most innocent of rocky trails. While we doubt that any real damage is done, the noise alone becomes disconcerting.
Second is that the Liberty is equipped only with three-channel ABS. That would not seem relevant in an off-road environment, but in a modern world, in which traction is generated through electronic systems based on four-channel ABS, the Liberty is at a definite disadvantage. Even with the optional Trac-Lok limited slip, which we had, the Liberty is not a hardcore off-road machine.
We think the 2.8L would be even better matched with a manual transmission, something like the new NSG370 six-speed, which is available this year with gas engines. But ours came with the 545RFE five-speed auto. It's a transmission we know and like, but in some environments, as in sand, we couldn't make it do what we wanted, and it affected the Liberty's performance.
While testers loved the engine, they were only marginally impressed with the Liberty's brakes and transmission. Off-road performance, respectable in many terrains, still lost points in sand and on rocky trails and hills. Finally, there were fewer functional hook points on the Liberty, something that became apparent when we tried to use it to rescue another 4x4 that had buried itself in sand. We still think the Liberty offers more guts and character than the average Cute Ute, and We hope to see more of the engine, because it sings.