Page 456 of 1336
1311-01
Layout and Location
Hydraulic chain tensioner
In G20DF engine, the hydraulic auto tensioner is used to keep the tension for chain drive system of
engine. The auto tensioner is operated by the spring in tensioner and the hydraulic pressure.
2) Hydraulic Auto Tensioner
Oil gallery
Page 459 of 1336
Clamping rail
Installed between intake
camshaft sprocket and
crankshaft sprocket
5) Chain Rails
The chain rails are used for optimizing the movement of chain drive system. And they also prevent the
chain from contacting each other when the chain is loose, and reduces the chain wear. The chain rail is
normally made of PA (Polyamide nylon), and PA66 and PA46 are used for the chain rails in G20DF
engine. For the tensioner rail, PA46 is used to provide high anti-wear function and high strength since
the load to the rail is huge. Ther is an open area for shoulder bolt hole in the clamping rail. The chain
rails are installed by shoulder bolts.
Tensioner rail
Installed between
exhaust camshaft
sprocket and crankshaft
sprocket
Page 460 of 1336
1130-13
1) Overview
Dual mass flywheel (DMF)
- Manual transaxleDrive plate
- Automatic transaxle
Dual mass flywheel reduces the unbalanced
rotation of crankshaft in manual transaxle
equipped vehicle. The flywheel is installed on the
crankshaft and is engaged to the clutch disc to
transfer the driving torque from the engine to the
powertrain system. Additionally, DMF decreases
the rattling noise in transaxle and the vehicle
vibration by reducing the differences of torque and
rotational speed due to the combustion in engine.The drive plate initially drives the powertrain
system by using the power from the start motor
when starting the engine. The drive plate is
installed on the crankshaft and is engaged to the
torque converter of automatic transaxle to transfer
the driving torque from the engine to the powertrain
system.
Page 461 of 1336
2) Operation of DMF
Compensating the irregular operation of engine: The secondary flywheel operates almost evenly so
does not cause gear noises
The mass of the primary flywheel is less than conventional flywheel so the engine irregularity
increases more (less pulsation absorbing effect).
Transaxle protection function: Reduces the torsional vibration to powertrain (transaxle) by reducing
the irregularity of engine. -
-
-
Compression stroke Combustion stroke
Small changes from engine (k):
Damper increases the torque changes to clutchLarge changes from engine (j):
Damper decreases the torque changes to
transaxle by absorbing the impact
Torque change curve of engine and drive shaft
Page 462 of 1336
1130-13
3) Features of DMF
Reduced vibration noise from the powertrain by blocking the torsional vibrations
Enhanced vehicle silence and riding comforts: reduced engine torque fluctuation
Reduced shifting shocks
Smooth acceleration and deceleration -
-
-
-
4) Advantages of DMF
Improved torque response by using 2-stage type spring: Strengthens the torque response in all
ranges (low, medium, and high speed) by applying respective spring constant at each
range.
Stable revolution of the primary and secondary wheel by using planetary gear: Works as auxiliary
damper against spring changes
Less heat generation due to no direct friction against spring surface: Plastic material is covered on the
spring outer surface
Increased durability by using plastic bushing (extends the lifetime of grease) -
-
-
-
Page 463 of 1336
Components
Piston assembly contains piston, #1 ring, #2 ring, oil ring, piston pin and snap ring. The expansion energy
from engine is transferred to the crankshaft through connecting rod to convert the linear movement to
rotating energy.Overview
Layout and Components
Top
Bottom
Oil ring
Piston ring
No.1 ring
Piston pin
No.2 ringSnap ring
Piston
Page 464 of 1336
1130-33
Functions
Piston transfers the combustion energy from engine to connecting rod.
C. Snap ring
Locks the piston pin. - A. Piston ring
#1 ring (Top ring) : Prevents the high pressurized combustion gas from leaking into crank chamber,
and prevents the engine oil getting into combustion chamber.
#2 ring: Scrapes the engine oil on the cylinder bore, and prevents the leaked combustion gas from #1
ring from leaking into the crank chamber.
Oil ring: Scrapes the engine oil on the cylinder bore. -
-
-
B. Piston pin
Connects the piston the connecting rod, and transfers the linear movement of piston to connecting rod
to convert it to rotating energy. -
Piston ring
Piston ring end gap (mm)
#1 end gap: 0.170 ~ 0.320
#2 end gap: 0.300 ~ 0.450Piston ring side clearance (mm)
#1 groove: 0.040 ~ 0.080
#2 groove: 0.040 ~ 0.080
Page 469 of 1336
Bottom of cylinder block Crankshaft sprocket installing surface
Crankshaft lower bearing Crankshaft lower bearing
Selection of crankshaft main bearing
Pin
punch
markColorDiameter of crankshaft
main journal in cylinder
block (mm)
* Blue 62.500 ~ 62.506
** Yellow 62.506 ~ 62.513
*** Red 62.513 ~ 62.519Mark ColorDiameter of
crankshaft main
journal (mm)
B Blue 57.960 ~ 57.965
Y Yellow 57.955 ~ 57.960
R Red 57.950 ~ 57.955
W White 57.945 ~ 57.950
V Violet 57.940 ~ 57.945
Engine
name
Main
journal
bearing
#1 #2 #3 #4 #5
G2 0DF
RRWWR