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3. CHECK AND INSPECTION
1) Cylinder
(1) Compression pressure test
Specified value
Compression ratio16.5 : 1
Test condition
Compression pressureStandard32 bar
Minimum18 bar
Differential limit between cylindersMaximum 3 bar
The compression pressure test is to check the conditions of internal components (piston, piston ring,
intake and exhaust vale, cylinder head gasket). This test provides current engine operating status.
Before cranking the engine, make sure that the test wiring, tools and persons are keeping away
from moving components of engine (e.g., belt and cooling fan).
Park the vehicle on the level ground and apply the parking brake.
Do not allow anybody to be in front of the vehicle. -
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Measurement
Disconnect the fuel rail pressure sensor connector to cut off the fuel injection.
Remove the air cleaner duct and glow plugs. -
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Place the diagram sheet to compression
pressure tester and install it into the plug hole. 1.
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Thickness marking
Ex: 1.3t
4) Cylinder Head Gasket
(1) Features
Sealing the cylinder gas pressure - Peak pressure: 190 bar
Minimizing the distortion of engine structure (cylinder head, block): profile stopper, backland stopper
Material: MLS (Multi Layer Steel), Gasket (3 layers)
Thickness of gasket: 3 types (1.2 /1.3 /1.4 mm) 1.
2.
3.
4.
(2) Thickness of cylinder head gasket
There are three types of gasket to managing the compression ratio.
Piston protrusion
Piston protrusion Thickness
0.475 to 0.540 mm 1.2t
0.541 to 0.649 mm 1.3t
0.650 to 0.745 mm 1.4t
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Torque change curve of engine and drive shaft
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
3) Operation
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. -
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1) Types of swirl
Swirl: One cylinder has two intake air ports, one is set horizontally and
the other one is set vertically. Swirl is the horizontal air flows in cylinder
due to the horizontal intake air ports.
Tumble: Tumble is the vertical air flows in cylinder due to the vertical
intake air port
Squish: Squish is the air flows due to the piston head. Normally, this is
appears at the final process of compression. In CRDi engine, the
piston head creates the bowl type squish.
2) Swirl control
In DI type diesel engine, the liquefied fuel is injected into the cylinder directly. If the fuel is evenly
distributed in short period, the combustion efficiency could be improved. To get this, there should be
good air flow in cylinder. In general, there are two intake ports, swirl port and tangential port, in each
cylinder. The swirl port generates the horizontal flow and the tangential port generates the longitudinal
flow. In low/mid load range, the tabgential port is closed to increase the horizontal flow. Fast flow
decreases the PM during combustion and increases the EGR ratio by better combustion efficiency.