Page 53 - E BOOK ENGINE MECHANICAL M2

2. TECHNICAL FEATURES OF 4D56 ENGINE

(4) Rocker Cover
A rocker cover gasket has a favorable construction to
durability that corresponds with the common rail system.

Fig. 2-4

(5) Cylinder Head Gasket
A carbon-coated gasket is inherited corresponding to
the high pressure in the cylinder, and it takes into con-
sideration the shapes of the cooling water holes of the
newer cylinder head.

Fig. 2-5

(6) Piston
A deep bowl type combustion chamber in the piston re-
quired for a direct injection system makes improvements
in the low speed torque.
To improve durability, the piston pin diameter is in-
creased and the dimension is reduced between the pis-
ton pin and the boss. A graphite coating is applied to the
skirt. To reduce the piston’s slap sound, the pinhole is
Graphite coating Pinhole offset drilled offset.
Fig. 2-6

(7) Valve Mechanism
In order to improve the engine performance correspond-
ing to exhaust gas regulation, a DOHC 4-valve con-
struction is used. 4 valves and an injection nozzle locat-
ed at the center optimize fuel combustion efficiency. By
using DOHC 4-valve construction with the roller rocker
arm, a higher output and lower friction are realized.
A compact designed gear drive is applied between the
intake and the exhaust cams, and the cylinder head.
The use of the scissors gear between cam gears, the
gear backlash noise is reduced.

Fig. 2-7

(8) Roller Rocker Arm
The lightweight rocker arm is made of steel plate. Along
with the roller follower, a lower friction is realized. A dou-
ble roller is used in the rocker arm construction. The roll-
er rocker arm is lightweight and stiff.
Rocker arm made of steel plate
Fig. 2-8

Pub. No. PTAE1228 2 - 2