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02-26
Intake/Exhaust Camshafts
2) Camshaft
(1) Overview
Hollow type camshaft contains cam, octagon cam, HP pump gear and intake/\
exhaust gears.
Camshaft operates the intake/exhaust valves, vacuum pump and HP pump, an\
d transfers the engine
oil to vacuum pump through the internal oil passage.
(2) Location
Exhaust CamshaftHP Pump Gear
Octagon cam
(for tooling)
Thrust journal
Connected to
vacuum pumpIntake Camshaft
Cross flow type water jacket (improving cooling performance)
▶
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02-270000-00
3) Valve Assembly (Installed in Cylinder Head)
(1) Features
Automatic valve clearance adjuster by hydraulic pressure (Maintenance Free) - Hydraulic lash
Optimized adjustment of valve clearance reduces the valve noise.
Roller type finger follower reduces the friction loss.
Vertical installation.
Simple and compact design reduces the moving operation (improving valve following and fuel
consumption at high speed) 1.
2.
3.
4.
5.
(2) Arrangement
Hydraulic lash adjuster
Upper valve spring retainer
Lower valve spring retainer
Valve spring
Exhaust valveIntake valve
Finger follower
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02-28
Thickness markingEx: 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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02-290000-00
(2) Layout
Chain upper bush
Type: single bush
Chains:112 EA
Tensioner rail
Installed between exhaust
Camshaft sprocket and
crankshaft sprocket
Hydraulic tensioner
Contains tensioner housing
plug, spring and check valve,
and operated by hydraulic
pressure
Crankshaft sprocket
Teeth: 21 EA
Oil pump sprocket
Teeth: 33 EA
Chain lower bush
Chain type: single bush
Chains: 60 EA
Mechanical type tensioner
Operated by internal spring
Clamping rail
Installed between exhaust
Camshaft sprocket and
crankshaft sprocket
Exhaust camshaft sprocket
Teeth: 42 EA
1) Chain Drive
(1) Overview
The drive chain is single chain drive system with simple design and variable performance, and it utilizes
the hydraulic tensioner to reduce the wave impact generated by the chain\
. This chain is light weight and
has high durability through single bush chain. Shoulder bolts are used f\
or better NVH.
7. CHAIN AND GEAR DRIVE SYSTEM
D20DTR engine uses single stage chain drive system. Timing chain drives the exhaust side and gear
drive the intake side. Timing chain is single bush ty pe. Upper chain drives HP pump connected to intake
Camshaft by driving exhaust camshaft sprocket, and lowe r chain drives oil pump to lubricate the engine.
25±2.5Nm
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02-30
2) Timing Chain and Gear
(1) Timing chain
Simple layout: optimized timing, enhanced
NVH
Single stage layout: minimized chain load -
-
Chain upper bush
- Single bush type (112 EA)
Chain lower bush
- Single bush type (60 EA)
(2) Tensioner
Tensioner adjusts the chain tension to keep it tight during engine running. This reduces the wear in
guide rail and spoke.
Operating principle
- Use the spring tension in tensioner and hydraulic pressure
Tensioner type
- Compensation and impact absorbing
Static and dynamic force
- Spring + Hydraulic pressure 1.
2.
3.
Plunger
HousingSpring
Check valve
Hydraulic tensioner assembly ▶
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Clamping guide rail
Installed between exhaust
Camshaft sprocket and
crankshaft sprocketTensioner guide rail
Installed between exhaust
Camshaft sprocket and
crankshaft sprocket
(3) Mechanical Tensioner Assembly
Operating principle
- Use only spring tension
Tensioner type
- Compensation and impact absorbing
Static and dynamic force
- Spring
(4) Guide rail
The guide rail is used for optimizing the movement of chain drive system. And it also prevents the chain
from contacting each other when the chain is loose, and reduces the chain wear.
The guide rail is made of plastic, nylon, Teflon, etc. The guide rail is specially required when the distance
between two spokes is too great. It pushes the chain with constant force so that the chain can work
smoothly. The guide rail is fitted by pins.
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02-32
Screw plug
Oil sealTiming gear case cover
(5) Timing gear case cover
Timing gear case cover (TGCC)
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Features
Major function: Protecting the chain drive system, minor function: Shielding the chain noise.
Install crankshaft front seal and screw plug on the timing gear case cover. ▶
-
-
Do not touch the inner lip of crankshaft front seal.
Be careful not to damage the screw thread when removing the lock pin to release the chain
tensioner.
Be careful not to damage the O-ring when installing the screw plug. -
-
-
A671 997 01 46
Crankshaft front seal
Location of chain tensioner screw
plug