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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
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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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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.
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Screw plug
Oil sealTiming gear case cover
Timing gear case cover (TGCC)
(5) Timing gear case cover
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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
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02-350000-00
Oil pan sassembly
8. OIL PAN
The oil pan in D20DTR engine improves the NVH. Especially, the oil draining is much easier than
before.
Components ▶