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Location of Expansion Plugs
1) Cylinder Head
(1) Overview
The cylinder is made by gravity casting and the water jacket is integrated type.
The cylinder oil passage is drilled and sealed by cap.
The Camshaft bearing cap is also made by casting and installed on the cylinder head.
(2) Features
Front
Oil gallery expansion plug (M10)
Coolant expansion plug (M21)
Intake side
Rear
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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, and transfers the engine
oil to vacuum pump through the internal oil passage.
(2) Location
Exhaust CamshaftExhaust Camshaft
Thrust journalIntake Camshaft
Closed flow type water jacket (improving cooling performance) ▶
Octagon cam
(for tooling)
Connected to
vacuum pump
Page 187 of 796
02-28
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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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
Thickness marking
Ex: 1.3t
Page 189 of 796
02-30
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 for better NHV.
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 type. Upper chain drives HP pump connected to
intake Camshaft by driving exhaust cam shift sprocke, and lower chain drives oil pump to lubricate the
engine.
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(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
The brass links on timing chain are aligned with the timing marks on crankshaft sprocket and
camshaft sprocket by eight turns of crankshaft.
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02-32
2) Timing Chain and Gear
(1) Timing chain
Simple layout: optimized timing, enhanced
NVH
Single stage layout: minimized chain load
The brass link on crankshaft is at symmetric
position of that on camshaft. -
-
-
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 railTensioner guide rail
(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.