Page 186 of 715
02-290000-00
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.
Page 187 of 715
02-30
(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.
Page 190 of 715
02-330000-00
Screw plug
Oil sealTiming gear case cover
Timing gear case cover (TGCC)
(5) Timing gear case cover
Page 192 of 715
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 ▶
Page 197 of 715
02-40
1) Piston
(1) Overview
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.
(2) Layout
#1 ring
Oil ring
Snap ring
#2 ring
Material:
B2+
Skirt coating:
MoS2
Piston cooling gallery
for connecting rod
Wide bawl type (CR 16.5)
Cooling jet
Page 198 of 715

02-410000-00
(3) Functions
Piston transfers the combustion energy from engine to connecting rod. Especially in the direct
injection engine such as D20DTF, it provides the combustion space and largely effects to the
engine performance and exhaust gas.
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.
Piston pin
Connects the piston the connecting rod, and transfers the linear movement of piston to
connecting rod to convert it to rotating energy
Snap pin
Locks the piston pin. ▶
-
-
-
▶
-
▶
-
(4) Assembling the piston
Install the piston rings with the "Y" mark on
the ring facing upwards.
Position the end gap of #1 ring at 180˚
away from the end gap of #1 ring.
Position the end gap of oil ring at 180˚
away from the end gap of coil spring, and
position the end gap of oil ring at 90˚ away
from the end gap of #2 ring. 1.
2.
3.
Page 201 of 715
02-44
NoConnecting
rod/ Bore
diameter in big
endUpper bearing Lower bearing
Journal
diameter of
crank pinOil
clearance o
f
bearing
GradeBearing
thicknessGradeBearing
thickness
1
54.600 R 1.804
B 1.812
50.935 0.017
1.808 1.815 0.063
2
Y 1.808
Y 1.809 0.016
54.614 1.812 1.812
50.960 0.062
3
B 1.812
R 1.806 0.015
1.816 1.809 0.061
Min. 0.015
Max. 0.063
(3) Selection of crankshaft pin journal bearing
The connecting rod bearing contains 3 sets of 3 grades in upper and lower sections.
Three sets in the table below have nearly same oil clearance (0.015~0.063 mm) of bearing.
Identification: Coloe mark on bearing side surface -
-
-
Oil clearance of connecting rod bearing
Page 205 of 715
02-48
Left sideExpansion plug
(3) Features
For simple manufacturing, the crankcase
blow-by gas passage and the oil return hole
are made by casting on the cylinder block.