Engine JAC HFC4DA1-2C. Service manual — part 16

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

63

Section VI Lubrication System

While the engine is working, all motion parts apply one specific force onto another part and generate relatively high
speed motion. With the relative motion, the friction is necessarily generated on the part surfaces, which will accelerate
the wear. Therefore, to relieve the wear, reduce the friction resistance, and prolong the service life, the engine must be
fitted with lubrication system.

z The engine oil filter is functioned to filter out the metallic wear dust, mechanical impurity, and engine oil oxide

from the engine oil. The ingress of these impurities into the lubrication system along with the engine oil will
speed up the wear of engine parts and may block the oil pipe or oil passage.

z The engine oil pump is of externally engaged gear pump and is driven by the crankshaft.

z The cooling nozzle of piston is arranged on the main oil passage to realize the stable oil spray for cooling. The

spray of engine oil into the cold oil passage within the piston can effectively reduce the thermal load of the
piston.

Valve

mechanism

Splash

Rocker arm bearing

Oil way

o

f

cy

li

nde

r bl

ock

Various cam

tappets

Splash

Various camshaft bearings

Various crankshaft

main bearings

Splash

Piston group

Timing gear

Turbocharger

Oil w

ay

o

f

cy

li

nde

r b

loc

k

O

il w

ay

of

cy

lin

de

r blo

ck

Co

olin

g noz

zle

By

pass

Engine oil filter

Engine oil cooler

Engine oil pump

T

u

rboc

har

g

er

o

il i

n

le

t

pi

p

e

T

u

rb

oc

har

g

er oi

l

ret

urn

p

ip

e

R

eli

ef

va

lv

e

Re

li

ef

va

lv

e

Main oil way

Oil ou

tle

t

pi

p

e

St

ra

in

er

Oil sump

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

64

Section VII Cooling System

z The cooling system is functioned to maintain the engine within an appropriate temperature range under all

working conditions.

z The cooling system can prevent the engine against overheating and prevent the engine from being too cold in

winter.

z After the cold start of the engine, the cooling system can guarantee the rapid temperature rise of the engine to

reach normal working temperature as soon as possible.

z Composition: Water pump, cooling fan, silicone oil fan clutch, thermostat, engine cylinder block, water jacket in

cylinder head, and other accessories.

z The cooling system is of enclosed forced recirculation water cooling type. Its structure is mainly composed of

radiator (water tank), water pump, fan, thermostat, cooling water jacket, and pipeline.

z The cooling recirculation of the heater system and engine oil cooler is always under working state and is not

subject to the restraints of large or small recirculation.

Dual thermostat control: When the water temperature is less than 82ºC, the thermostat is under natural state (namely
the cooling water from the water tank is closed and the cooling water from the cooling module is opened). In such
case, the cooling circuit works in the small recirculation circuit and the cooling water from the cooling module enters
into the engine block and cylinder head for recirculation through the water pump so that the temperatures of the water
and oil in the engine block and the cylinder head will rise. When the water temperature reaches 82ºC, the thermostat
starts to open. When the thermostat is opened, the small valve closes the small recirculation circuit. As the thermostat
is not fully opened, the cooling water from water tank enters into the cylinder block for large recirculation through
water pump. If the water temperature continues to rise to 95ºC, the thermostat valve is fully opened.

Water tank

Radi

ator

Cylinder head

Cylinder block

Thermostat

Water pump

Heat

er

Oil cooler

Inlet of

water

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

65

Section VIII Turbocharger and Inter-Cooler System

The turbocharger technology utilizes the motion energy of engine exhaust gas to drive the rotation of turbine. At the
same time, the coaxial air compressor compresses the air and provides more air to the cylinder so that more fuel can
combust to generate higher power, promote the engine torque, and reduce the fuel consumption.

The common turbocharger is of bypass valve turbocharger, which can’t provide sufficient pressure while the engine is
running at low speed and thus restrains the torque output at low speed and influences the engine performance. To
change this situation, the 1.9CTI engine adopts variable nozzle turbocharger (VNT) control system to promote the
turbocharger pressure at low speed of engine and at the same time adopts inter-cooler system to exert higher torque at
low speed of engine and promote the engine performance.

Theory of inter-cooler: The temperature of the air compressed at high speed may reach 100~120ºC. The high
temperature air will impair the intake efficiency of the engine and lead to power drop of the engine. Therefore, it’s
necessary to cool down the air to approximate 60ºC. The inter-cooler is located in front of the radiator or at windward
position easily arranged, in order to reduce the temperature of air entering into the cylinder, further improve the
combustion of diesel engine, and promote the performance and emission of the diesel engine.

Variable nozzle turbocharger (VNT): The VNT is functioned similar to one turbine housing in which the size is
varying steplessly. The VNT actuator can accurately control the nozzle area within the entire working condition range
so that the engine can not only maintain the turbine efficiency at high speed, but also increase the turbine efficiency at
low speed, promote the torques at low speed, maximum torque output, and nominal working condition, improve the
cold start performance and low speed performance of turbocharged diesel engine, realize high specific power and low
speed torque of the engine simultaneously, and greatly reduce the smoke intensity and improve the economy.
Meanwhile, the VNT can reduce the turbine lag, improve the engine response, and enhance the braking capability and
safety.

Adjustment theory for variable nozzle turbocharger (VNT): There are two passages, one is in constant section and one
is in variable section. If the pressure is same for two passages, the speed of airflow passing through the variable

Engine

Inter-cooler

Compressed air

Intake

Exhaust gas of engine

Exhaust

Turbocharger

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

66

section passage is greatly higher than that passing through the constant section passage.

Idling of

engine

Small passage

section

Large passage

section

High speed

running of engine

Rotation direction of adjustment ring