All-new 3.7-liter V-6 Powers Up
2OO2 Jeep Liberty
Best-In-Class Horsepower and Torque

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Combining power and refinement, the 2002 Jeep Liberty muscles ahead of and apart from the pack with an all-new 3.7-liter Power Tech V-6 engine. Designed in conjunction with the highly acclaimed 4.7-liter Power Tech V-8, which debuted in the award-winning 1999 Grand Cherokee, the 3.7-liter brings the fun-to-drive and quality hallmarks of every Jeep vehicle to the Liberty. Both the Sport and Limited Edition models of Liberty benefit from this all-new engine in either two- or four-wheel drive versions.

“Our Jeep vehicles are meant to be as enjoyable on-road as they are off,” said Craig Love, Vice President—Jeep Platform Engineering, DaimlerChrysler. “This all-new 3.7-liter engine was designed for power and refinement, giving our customers that fun-to-drive excitement that Jeep vehicles are known for.”

Powertrain Lineup
The Jeep Liberty Sport features as standard the 2.4-liter Power Tech I-4 engine with a five-speed manual transmission. The 2.4-liter engine is rated at 150 horsepower (112 kW) at 5200 rpm and 165 lb.-ft. (224 N•m) of torque at 4000 rpm. The all-new 3.7-liter engine mated to a five-speed manual transmission is standard on the Limited Edition model and optional on the Sport. Equipped with the 3.7-liter engine, Liberty pumps out 210 horsepower (157 kW) at 5200 rpm and 235 lb.-ft. (319 N•m) of torque at 4000 rpm, giving the newest Jeep vehicle the highest horsepower and torque ratings in its class. Four-wheel drive Liberty vehicles are equipped with the tried-and-true NV231 Command Trac® part-time transfer case or the optional full-time NV242 SelecTrac® transfer case. The 45RFE Multi-speed Electronic automatic transmission is available only with the 3.7-liter engine. An all-new 2.5-liter Power Tech common rail direct injection turbocharged I-4 engine is available for international markets.

3.7-liter Engine Highlights
The 3.7-liter engine was developed in conjunction with the highly acclaimed 4.7-liter V-8, and shares a common architecture and many components. Like the 4.7-liter, this all-new engine features chain-driven overhead cams to provide long-term durability and reliability. A fabricated tubular camshaft with powder metal lobes helps reduce engine weight. A system proven on the 4.7-liter, the 3.7-liter was designed to be completely “dry”—no oil or coolant leaks from
the engine. Premium gaskets and seals are used throughout, resulting in a significant, tangible benefit to both customers and the environment.

Several features are unique to the 3.7-liter engine. A gear-driven balance shaft minimizes engine vibration. The composite intake manifold has individually tuned runners for improved performance. An active knock sensor system—with sensors on each cylinder bank—increases mid-range performance with regular unleaded fuel.

Solid Construction
The 3.7-liter has a 90-degree V-6 design with cast iron block, compacted graphite bedplate and aluminum cylinder heads with single overhead cams on each bank. This engine incorporates
a centrally-mounted counter-rotating balance shaft, along with a split-pin crankshaft to provide an even firing order and balanced 90-degree V-6.

A tuned intake manifold—providing optimum air flow for higher power—has shorter runners than the 4.7-liter engine, to produce torque and power peaks at higher speeds. The three-piece shell molded plastic manifold provides individual tuned runners for each cylinder. Molded plastic construction provides more air flow than a cast aluminum manifold with the same dimensions because of its smooth inner walls. Lightweight aluminum pistons and precision forged, powder metal connecting rods reduce reciprocating weight, contributing to the engine’s high rpm capability.

Designed to get more power out of less displacement, the 3.7-liter engine maximizes air flow through the engine. High air flow was achieved through hundreds of hours of computer simulation used to optimize every aspect of the air flow equation, from the air cleaner inlet to the tail pipe. Splayed valves and large uniform intake ports, made possible by using overhead camshafts, ensure that abundant air flow enters each cylinder in the same way.

Fast-burn combustion extracts more work from a given amount of fuel, increasing efficiency. Spark plug location near the center of the combustion chamber allows rapid combustion without potentially damaging knock. Rapid, complete combustion maximizes the amount of energy in a given amount of fuel that is transferred to the piston as useful work.

Refinement at All RPMs
The all-new 3.7-liter offers a very refined driving experience. The combustion chamber design, combined with the tuning of the intake manifold and air induction system, give the engine a good sound quality and level during all ranges of operation. Cylinder head-mounted fuel injectors use a wider spray pattern at the intake valves, which enhances complete combustion for quick response and smooth operation under all operating conditions.

“When the customer steps on the accelerator they have certain expectations for how the vehicle should sound and feel,” continued Love. “Our engineers did extensive noise, vibration and harshness testing to develop a consistent and level sound quality throughout the operating range to delight the customer.”

To meet customer durability expectations, the all-new 3.7-liter passes tests replicating the most extreme conditions. A systematic approach to sealing, using premium materials and state-of-the-art practices, ensures a leak-free engine. Molded, high-temperature gaskets provide lifetime sealing of all structural joints. The drive overhead camshafts uses three chains with an intermediate shaft to provide the necessary speed reduction in a compact package and to ensure reliability. Direct mounting of the alternator, power steering pump and air conditioning compressor on the front cover of the engine provides accurate alignment to minimize belt wear and noise. An automatic tensioner for the single serpentine poly-vee belt makes adjustment unnecessary for the life of the belt.

State-of-the-Art Transmission
In the 2002 Jeep Liberty, the 3.7-liter engine is mated to the NV3550 manual transmission or optionally with the 45RFE Multi-speed Electronic automatic transmission. The smooth-shifting NV3550 manual transmission has been refined for use in the new Liberty. A reverse lock-out prevents accidentally shifting into reverse when downshifting into fourth gear, avoiding possible gear clash. A new clutch disc contributes to quieter transmission operation, and has longer, lower-rate damper springs to reduce torsional vibrations at the transmission input shaft.

The 45RFE Multi-speed Electronic automatic transmission, first introduced in the 1999 Grand Cherokee, offers many advancements not found on other transmissions. Drawing on 10 years of experience in building electronically controlled automatic transmissions, the 45RFE provides world-class shift quality with a real-time adaptive closed-loop shift control.

The 3.7-liter engine, equipped with a multi-speed automatic transmission, provides 5,000-pound towing capability that can’t be beat.

Jeep-Engineered Transfer Cases
The NV231 Command Trac and NV242 Selec Trac transfer cases include stronger main shafts to absorb higher torque peaks. A needle bearing on the shift mechanism reduces shift effort and improves shift feel. With manual transmission-equipped vehicles, a rubber-isolated torsional damper on the transfer case output shaft makes for quieter transmission performance.

The powertrain system works as a whole to improve the off-road capabilities of the Liberty with unique features and outstanding performance in low range, such as clutch interlock override on manual transmissions, calibrated vehicle crawl speed, engine braking on grades and obstacle climbing.

A new sensor on the transfer case shift mechanism indicates every range. With the 45RFE transmission, it is used by the transmission control module to determine shift speeds. It also provides the signal that illuminates the low-range indicator light in the instrument cluster and aids off-road operation with manual transmission models by overriding the clutch-starter interlock when low range is selected. With anti-lock brakes, it activates a separate calibration to improve stopping performance during off-road operation.

To meet more stringent exhaust emission regulations, the exhaust system of the 3.7-liter

LEV includes two mini-catalytic converters, one for each cylinder bank in addition to a main underbody converter.

Benchmark Manufacturing
The all-new 3.7-liter engine is produced at DaimlerChrysler’s Mack Avenue engine plant in Detroit. This all-new, state-of-the-art assembly plant is located adjacent to the 4.7-liter engine plant. Like the two engines, the 3.7-liter and 4.7-liter plants are similar in concept and layout. Once the 3.7-liter plant is fully operational, it will be the DaimlerChrysler benchmark for engine plant quality and productivity.

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