The all aluminum engine block utilizes a deep skirt
design for increased rigidity. The cylinders are
positioned in a straight in-line 6 cylinder
orientation. The crankshaft bearing caps have a
bearing beam or "ladder" for enhaced structural
rigidity and vibration reduction.

Oil Pan.
A single piece cast aluminum oil pan contributes to
crankshaft and block rigidity while reducing overall
weight. The oil pan bolts to the bell housing as well
as the block. This eliminates points of vibration and
makes the complete powertrain act as a single
casting. Jack screws are used to remove the oil
pan.

Crankshaft.
The crankshaft is a nodular iron design with seven
main bearings.

Connecting Rods.
The connecting rods are forged powdered metal.
The connecting rods and caps are of a fractured
split design to improve durability and reduce
internal friction. Care must be taken to ensure the
mating surfaces are not damaged during service
procedures.

Pistons.
The pistons are a full-floating design. The piston
pins are a slip fit in the bronze bushed connecting
rod and are retained in the piston by round wire
retainers. There are two compression rings and
one oil control ring.
4.2L Engine Mechanical Operation Description

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Cylinder Head.
The cylinder head is also made of the lost foam aluminum for
lighter weight and rapid heat dissipation. There are 4 valves
per cylinder and the ports are of a high swirl design for
improved combustion. The cylinder head gasket consist of a
steel laminated construction.


Valve Train.
The engine utilizes dual overhead camshafts and roller
followers for reduced friction, which results in improved gas
mileage.

Fuel System.
A new electronic throttle control system is used on the engine.
A throttle actuator control or TAC system eliminates cable
linkage from the pedal to the throttle control module. All
throttle movements are controlled by the PCM.

Oil Pump.
The oil pump is gear driven directly from the crankshaft. The
oil pump drive gear is a slip fit to the crankshaft.

Engine Covers.
There is a front engine cover and a rear engine cover, both are
made of aluminum. The front engine cover and rear engine
cover have "T" sealing joints and need to be removed after the
oil pan. The front and rear covers need to be installed before
the oil pan. Jack screws are used to remove the covers. Guide
pins are used to aid in the installation of both covers.