ENGINE ZNA RICH

MODEL FOR RICH(Y40F)

SERVICE MANUAL

RCHRM2A21

QUICK REFERENCE INDEX

Y40F Engine for ZG24

GENERAL INFORMATION

GI

MAINTENANCE

MA

ENGINE MECHANICAL

EM

ENGINE LUBRICATION & COOLING SYSTEM

LC

ENGINE CONTROL SYSTEM

EC

ACCELERATOR CONTROL ,FUEL& EXHAUST SYSTEMS

FE

CLUTCH

CL

MANUAL TRANSMISSION

MT

TRANSFER

TF

PROPELLER SHAFT & DIFFERENTIAL CARRIER

PD

FRONT AXLE & FRONT SUSPENSION

FA

REAR AXLE & REAR SUSPENSION

RA

BRAKE SYSTEM

BR

STEERING SYSTEM

ST

RESTRAINT SYSTEM

RS

BODY AND DECORATION

BT

HEATER& AIR CONDITIONING

HA

ELECTRICAL SYSTEM

EL

ZG24

Engine machnical

SECTION

EM

Contents 1

ZG24Engine Outline

2

ZG24 Engine characteristics curve

3．Technical parameters of ZG24-type gasoline engine 。

4

Advanced performance overview of ZG24-type gasoline

engine 5

Typical structure and its advantages of ZG24-type gasoline

engine 6

16-valve mechanism (4-valve mechanism of each cylinder).

7

The structure of double overhead camshaft

8

Major advantages：

9

Gapless gear drive (between double overhead camshaft)13

10

Disassembly and assembly key points of ZG24-type gasoline

11

engine main parts

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ZG24 1. ZG24Engine Outline

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ZG24

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ZG24

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ZG24

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ZG24

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ZG24 2. ZG24 Engine characteristics curve

ZG24 Total power curve

 C  o r  r   e   c   t   i    o n  e  f   f    e   c   t   i    v  e 

E f   f    e   c   t   i    v  e   t    o r   q  u  e 

Fuel consumption

F   u  e  l    c   o n  s   u m  p  t   i    o n

F   u  e  l    c   o n  s   u m  p  t   i    o n

Engine Speed(r/min)

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ZG24 3.

Technical parameters of ZG24-type gasoline engine

Model of engine

4RB2

Cylinder Qty（ mm）

4

Cylinder 95×86

diameter×stroke （ mm）

Total （L）

displacement

2.438

Idling speed （r/min）  Total

750±50

power/rotation

102/4600～5000

speed （kW/ r/min） Maximum torque/rotation

217/2600～3200

speed 

（ Nm/ r/min）

Fuel supply method

Closed-loop control and multi-point sequential injection

Pollutant

emission

Meet 1999／102／EC EuroⅢ  Emission  Limit

limit value

#93 or #95 quality unleaded gasoline

Fuel brand

（GB17930）

Engine oil brand

SG-class 10W-30 or 15W-40

Compression ratio External （ mm）

9.2

dimensions

760×552×670

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ZG24 4. Advanced performance overview of ZG24-type gasoline engine

4.1 Advancement of electric control system Electric control system (MT20U2 system for short) of ZG24-type gasoline engine is the system with Delphi MT20U2 engine control module (ECM) at the core. Viewing from its functions, it has been able to meet relevant technical requirements of Euro Ⅲ  and Ⅳ Emission Regulations. Meanwhile, it also reserves relevant functions of European On-Board Diagnostic (EOBD). 4.2 Possessing well dynamic performance This engine has characteristics of high power （102Kw）and high torque （217N.m）. Torque characteristic curve is smooth and the engine has well

easement and acceleration capacity. 4.3 Excellent emission performance Because advanced combustion system, ignition control technology, modern electric control fuel injection technology and ternary catalytic instruments are adopted to carry out off-engine purification, emission index of this engine meets requirements of Euro Ⅲ Regulation in one go. （It has respectively passed relevant emission detections: 9-mode test cycle experimental emission detection, 15-mode test cycle emission detection, crankcase ventilation emission detection and double idle emission detection, etc）. 4.4 Compact conformation, small volume and light weight

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ZG24 In

overall

arrangement:

ZG24-type

gasoline

engine

adopts

chain-driving double overhead camshaft (without bearing), portal cylinder  body without cover, ultrashort cylinder center distance （102.5）and short connecting rod (hole distance 135）, water channel and oil duct with optimum design, which reduce integrated dimensions of the engine; on aspect of accessories: oil pump and water pump attaching on sprocket room, starter lightweighting, spin-on filter and reinforced polypropylene fan, etc. make accessories system have light weight and small volume; on aspect of material selecting: aluminous cylinder cap and sprocket room, etc are adopted, which further reduces weight of the complete machine (total mass is 165kg and specific mass is 1.62kg/kw). 4.5 Excellent fuel economy ZG24 adopts advanced combustion chamber mechanism, high compression ratio and multi-point electric control fuel sequential injection, strict matching calibration, which make its combustion more sufficiently. Therefore, it possesses very high thermal efficiency and broad economic zone; long-channel air inlet pipe is adopted to improve charging efficiency; lightweighting piston linkage mechanism, typical convex skirt piston, silicone oil clutch fan and other structures are adopted to improve mechanical efficiency. Inlet/exhaust valve forms a certain inclination with the plumb direction, in this way the spark plug can be put near the center of

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ZG24 combustion chamber, which is in favor of cyclic flame spreading and improving fuel economy, especially fuel economy under partial load. 4.6 Low vibration and noise Because ZG24 adopts advanced structure and combustion process, strict ignition timing calibration and optimum adjusting in knocking zone, which reduce mechanical movement noise and combustion breakout noise; double-layer valve chamber cover cap structure reduces noise transmission in valve chamber; for engine block and cylinder cap design, its external surface adopts structure and measures reducing internal exciting force response, which further reduces noise. Crankshaft-piston-connecting rod gear with lightweighting design and  belt pulley and silicone oil clutch fan with rubber vibration isolato r make this engine have small vibration and low noise. Camshaft directly running in aluminous cap is in favor of reducing noise.

4.7 Convenient maintenance Design and arrangement is brief and compact; integration degree of ignition and electric control system is high and clear; overhaul of all parts is convenient; the chain automatically keeps constant pressure and tightening, etc, which greatly simplify and facilitate maintenance work. 5. Typical structure and its advantages of ZG24-type gasoline engine

5.1 16-valve mechanism (4-valve mechanism of each cylinder)

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ZG24 Modern vehicle has a higher and higher performance requirement on vehicle power---engine: increase power per liter, improve dynamic and sensibility of the engine under different operating conditions and meanwhile, improve fuel consumption and reduce exhausting pollution, therefore, 4-valve mechanism receives more and more attention, its advantages are: （1） Air inlet flow area increases, flow resistance reduces, therefore,

coefficient of charge increases, pump gas loss reduces and torque per liter and power per liter of the engine increases. （2）Inlet channel design freedom is large, shape of combustion chamber

is near hemispheric, spark plug can be put in position near the center, which is in favor of organizing gas mixture in cylinder to form tumble and swirl and realize fast burning. It can properly improve compression ratio and reduce oil consumption and HC compositions emission. （3） Moving parts of valve train have small mass, small inertia force and

strong structural rigidity, which is in favor of

improving engine speed

and reducing engine noise. 5.2 The

structure

of

double

overhead camshaft

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ZG24 Major advantages： （1）Valve mechanism is directly driven by double overhead camshaft（DOHC) and there is no push rod or rocking arm, which reduces inertia mass, i.e. reduces inertia force of valve mechanism and consequently reduces vibrating trend of valve and deformation amount of valve mechanism. （2） It can reduce valve clearance and reduce noise to the maximum

extend. （3） Improve follow-up characteristic of valve to camshaft and increase

engine speed. （4） Small inertia mass of the structure enables valve to open and close

rapidly, prolong full opening time of valve, improve ventilation operating condition of cylinder, increase volume efficiency of combustion chamber and consequently greatly increase engine performance. 5.3 Gapless gear drive (between double overhead camshaft) Driving disadvantages of traditional gear: tooth flank is liable to be worn. After wearing, timing accuracy of engine reduces. In order to prevent gear thermal

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ZG24 expansion clocking, enough clearance must be left between two driving gears, therefore very big noise will be generated when running. ZG24 adopts the structure of gapless gear drive: the structure consists of master gear and pinion. There is a torsion spring clamped between master gear and pinion. Two ends of the torsion spring prop up two pins respectively fixed on master gear and pinion. The torsion spring make tooth flanks of master gear and pinion form a small angle. The form look like scissors. With this structure, when temperature reducing, clearance between driving gear and driven gear of double overhead camshaft is comparatively  bigger, at this point, under the elastic force of torsion spring, the two tooth flanks of master gear and pinion of gapless gear form a small angle to fill up the clearance between driving gear and driven gear. Vice versa. Advantages of this structure: increase timing accuracy; reduce engine noise. 6. Disassembly and assembly key points of ZG24-type gasoline engine main parts

6.1 Assembly of cylinder cap

Cylinder cap is also one

of

the

important

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ZG24 components of engine. It mainly integrates main components and parts (camshaft, valve and tappet, etc.) of valve mechanism and some components and parts (e.g. spark plug, etc.) of ignition system, by which normal air inlet, exhaust, ignition, combustion, apply work etc. can be completed. Cylinder cap of ZG24-type gasoline engine is forged with aluminum alloy. It has cross-flow inlet & exhaust channel, awning combustion chamber; its spark plug lies in the center of combustion chamber; inlet and exhaust respectively has 5 camshaft fulcrum bearings and fulcrum bearing caps; oil injector

is

installed

on

cylinder cap. Adopt thin-wall cast aluminum alloys valve chamber cover with the structure of vibration reduction and sound deadening. Dismantling key points of cylinder cap parts

Put piston of the first cylinder on the position of top dead center. Rotate crankshaft pulley to

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ZG24 make timing mark of the pulley align at the mark of “0” on cap of sprocket room. As shown in drawing.

Dismantle high voltage line, spark plug, cylinder cap, ignition coil, inlet manifold support strip, oil pipe and uncoupling cooling water bypass hose, etc. Dismantle timing sprocket of admission camshaft. Make assembly mark on sprocket and chains, as shown in drawing.

Dismantle bolt of admission camshaft sprocket, chain tightener assembly and washer, dismantle timing sprocket of admission cam shaft, camshaft bearing cap and camshaft from admission cam shaft.

Unscrew camshaft bearing cap bolt, dismantle camshaft  bearing cap and camshaft and dismantle cylinder cap in 2～3 steps according to the drawing.

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ZG24 Firstly screw off the 2 bolts in front of cylinder cap, as shown in drawing. Then according to the sequence shown in drawing, gradually screw off 10 cylinder head bolts and dismantle cylinder cap in 2～3 steps. Inspection of cylinder cap

Inspection of worn condition of valve seat: Inspect worn condition of valve seat and whether there is damage and if necessary, should reseat valve seat. At this point, should firstly inspect worn condition of valve guide, if it has been worn excessively, should firstly replace valve guide; then thin the valve seat with valve seat reamer or valve seat grinder. Valve seat should be machined into the shape shown in the drawing; the width of contact segment of valve seat and valve-face is 1.0 mm～1.4 mm. Finally, grind valve and valve seat with valve grinding compound to make it joint closely without air leakage. After grinding, completely clean valve seat, valve and internal hole of valve guide. Grinded valve should not be replaced. Refer to relevant technical documents for inspection of other  parts.

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ZG24 Assembly key points of cylinder cap parts

Valve and valve seat should be sealed reliably. After assembling spark  plug, fill the combustion chamber with coal oil and observe that there is no obvious leakage within 1min. When assembling valve oil seal, should not damage or scuff the lip; when assembling the locker, should not scuff valve stem. When assembling tappet and washer, ensure inlet valve clearance to be 0.15 mm ～0.25 mm and exhaust valve clearance to be 0.25 mm ～0.35 mm. 1)

Assembly of cylinder cap

Assemble cylinder cap on engine block and fix it with pin bush. Apply sealant at the joint part of sprocket room and engine block and assemble cylinder cushion and cylinder cap (as shown in drawing).

Apply small amount of engine oil to screw thread of cylinder head  bolts and screw down the 10 bolts as per sequence shown in the drawing.

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ZG24 Screw down force of the first time is 39N.m ± 4 N.m, screw down of the second time is 90°±5° and the third time 90°±5°. 2)

Assembly of camshaft

When assembling camshaft, should firstly clean joint line and apply appropriate amount of engine oil to shaft neck surface of camshaft; then, put camshaft and camshaft bearing cap. Back and forth direction of camshaft and sequence number and forward mark of camshaft bearing cap must be correct and knock on camshaft bearing cap slightly with rubber ha mmer to the designated position. Then apply a small amount of engine oil to screw thread of camshaft bearing cap bolts, screw down with fixed torque wrench and the tightening moment is 16N.m±3 N.m.  Notice: When assembling admission cam shaft, should make camshaft angle  position upward; when assembling exhaust cam shaft, should align timin g mark on driving gear of admission cam shaft with that on gear of exhaust cam shaft.

3)

Assembly of timing

sprocket of admission cam shaft

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ZG24 Lift sprocket and chains with hand. Meanwhile, rotate the crankshaft until piston of the first and the fourth cylinders being put on the position of top dead center. Rotate crankshaft to align timing mark on gear of admission cam shaft with that on gear of exhaust cam shaft and make them on the same straight line (angle positioning pin on admission cam shaft should be upward); align the sprocket with the angle positioning pin on admission cam shaft and assemble it, then assemble bolt and screw down.

4)

Assembly of tightener

Loosen the pawl, completely press the gear rack in and cover the pin

hook on fixed pin to make the gear rack can not spring out; assemble washer and tightener to the designated position together and screw down with 2 nuts. Rotate the crankshaft to make pin hook of tightener come away from fixed pin of gear rack, the gear rack will spring out and make the crawler shoe bear down on chains, and consequently tighten chains.

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ZG24 5)

Inspection and adjusting of valve clearance

Inspection of valve clearance Rotate crankshaft  pulley to make it on the  position of top dead center of first cylinder compression. Inspect whether valve clearance shown in top part of the drawing is correct with clearance gauge, otherwise should replace washer and make adjusting. Rotate crankshaft pulley for a circle and align the groove of pulley with timing mark “0”, Inspect whether valve clearance shown in bottom part of the drawing is correct with clearance gauge, otherwise should replace washer and make adjusting. Inlet valve Clearance

0.15 mm～0.25 mm

Exhaust valve 0.25 mm～0.35 mm

（cold state）

Adjusting of valve clearance

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ZG24 Press valve tappet down with valve clearance adjusting clamp and keep the valve tappet on the position of downward with valve clearance adjusting supporting rod. Take off washer with valve clearance adjusting plectrum, inspect and adjust valve clearance.

6.2 Timing sprocket mechanism Dismantling key points of timing sprocket mechanism

After dismantling cylinder cap, dismantle followings accords to sequence: fan belt, silicone oil clutch (fan), water pump pulley, AC generator, crankshaft pulley, oil pan, oil filter, sprocket room, cam shaft timing sprocket, admission cam shaft timing sprocket, crawler shoe subassembly, vibration damper plate subassembly, crankshaft timing sprocket. Inspection of timing sprocket mechanism

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ZG24 Straighten the chain, and choose 3 to 4 positions to measure the total length of chain of 16 sections, whose length should be 142.875 mm. And if the value is higher, the chain should be replaced. Inspection of sprocket is conducted as the drawing. The minimum value of admission cam shaft timing sprocket is 113.8 mm. Inspection of subassembly of crawler shoe and vibration damper plate focuses on whether the maximum abrasion loss is 1mm. Assembly of timing sprocket mechanism

Rotate crankshaft to make keyway upward, and install woodruff key and crankshaft timing sprocket. Install subassembly of crawler shoe and vibration damping subassembly. Assemble cam shaft timing chain and admission cam shaft timing sprocket.

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ZG24 When crankshaft timing sprocket is installed to crankshaft timing sprocket, align black chain-timing mark of chain with timing rut mark of cam shaft timing sprocket. Align timing mark of admission cam shaft timing sprocket with corresponding timing mark of cam shaft timing chain. Make sure that subassembly of crawler shoe and vibration damper plate are assembled in right place. Wrap chains, subassembly of crawler shoe and vibration damper plate together with soft cord to avoid loose. Assemble sprocket room, oil filter , oil pan, crankshaft pulley, AC generator, water pump pulley, silicone oil clutch (fan), fan belt and cylinder cap in sequence.

6.3 Assembly of cylinder body Cylinder where

body,

many

essential

components

of

engine

(crankshaft,

oil

 pump,

and

piston

assembled,

etc.) is

are an

important frame of engine.

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ZG24 The indispensable working surroundings of engine are composed of cylinder and cap. Engine can apply work outwards due to combustion chamber composed of cylinder body and cap. And water jacket ensures engine working under a normal temperature. Oil duct gives excellent lubricating conditions to each component. A complete closed loop is formed through assembling each component. Cylinder body of ZG24-type gasoline engine adopts portal, i.e. bottom  plane of cylinder body is lower than assembly plane of crankshaft, which obviously improves flexural stiffness of longitudinal plane and torsional rigidity of encircling axis of crankshaft and is good for consolidation and improvement of engine. Meanwhile, bottom plane of cylinder body forms an integrated plane matching with oil pan making sealing easily. Because of adopting dry liner, which combines cylinder and cylinder  body into integrity, structure is simple and compact, and rigidity overwhelms wet liner. Cylinder body adopts fully supporting type, making distribution of load more even. Dismantling key points of components of cylinder body

Subassembly of piston connecting-rod Before taking out subassembly of piston connecting-rod, shall place rubber sheath or plastic sheath on connecting-rod bolt to prevent from damaging crankshaft connecting-rod journal. Collocate bearing bushes of dismantled subassembly of piston

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ZG24 connecting-rod in right order. Don’t change the order when assembling. When dismantling main bearing cap, main bearing bush, crankshaft and thrust washer, place them in order for easy assembly.

Inspection of components of cylinder body

Standard Value

Axial Connecting

clearance

rod

Radial

0.160 mm～0.312 mm

0.032 mm～0.058 mm

clearance Axial

Max

Measures

Value

 beyond Scopes

0.35 mm

Replace

0.10

components

mm 0.040 mm～0.212 mm

-

clearance

thrust

washer 0.030 mm ～ 0.057 mm

0.10

Radial

（The third main journal）

mm

clearance

0.025 mm ～ 0.049 mm

Crankshaft

Replace

（The other main journal）

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Replace

main

 bearing bush

ZG24

Diameter of

94.995 mm～95.005 mm

-

If

95.005 mm～95.015 mm

-

maximum

95.015 mm～95.025 mm

-

diameter

exceeding

or

bore  piston scraping

hole appears,

 bore

cylinder

or

replace cylinder Upper

plane

of 0.05 mm（ planeness）

-

cylinder

Piston diameter

Piston

to

94.925 mm～94.935 mm

-

94.935 mm～94.945 mm

-

94.945 mm～94.955 mm

-

cylinder 0.042 mm～0.062 mm

clearance

0.1

Replace piston

mm

or bore cylinder

 No.1: 0.030 mm ～ 0.70 mm Ring groove clearance

Replace piston  No.2: 0.030 mm ～ 0.70 mm

Piston

ring

Joint No.1: 0.25 mm～0.40 mm

Replace piston

clearance Clearance

 No.2: 0.40 mm～0.55 mm  between 0.005 mm～0.011 mm

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0.015

ZG24  piston pins and holes between 0.005 mm～0.011 mm

Clearance

0.015

 piston pin and small head

pore

of

connecting rod Diameter of screw pile 7.8 mm～7.9 mm

7.6

of connecting rod

mm

Radial runout of main Max 0.03 mm

-

axis of crankshaft

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ZG24

Key points of assembling components of cylinder body

1)

Assembly of crankshaft and main bearing bush

Choose corresponding main bearing bushes according to number of rear main axis hole of downward plane of cylinder body, and install them in corresponding cylinder bodies and main bearing cap.  Notice: put bearing bush with oil holes into cylinder, and apply a little engine oil on the inner side of main bearing bush. As in the drawing, put thrust washer in the both sides of No. 3 main gear seat of cylinder, with oil groove outwards. As shown in drawing.

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ZG24

Put crankshaft in the cylinder with main bearing bush. As in the drawing, put lower thrust washer at the both sides of No. 3 main bearing cap of cylinder with oil groove outwards, and put main bearing cap in the right places according to arrowhead and original sequence. As shown in drawing. Before assembling main bearing cap bolt, should lay a little engine oil on screwthread parts, and screw tightly main bearing cap bolt alternately from the middle to both ends twice. As shown in drawing. Tightening moment is 39  N.m. Mark at the forepart of the top of bolts, and rotate 90° as in the drawing to

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ZG24

further tighten bolts. Rotate crankshaft to check whether it is flexible and whether there is  jamming phenomenon, and examine axial clearance of crankshaft.

2)

Assembly of piston connecting rod mechanism

According to the size of connecting rod big-end hole, categorize and choose corresponding connecting rod bearing  bush, put it into big-end and hole of connecting rod cap, bearing bush with oil holes into big-end of connecting rod. Cover connecting rod bolt with flexible tube, and apply a small amount of engine oil on the cylinder wall

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ZG24 and journal of crankshaft connecting-rod.

Install piston connecting rod mechanism into taper sleeve to make depression mark of piston align at the frontage of cylinder, and slightly push subassembly of piston connecting rod into cylinder. As in the drawing, assemble connecting rod cap to ensure the right direction of onward mark of connecting rod cap, and connecting rod cap and the original connecting rod are matched. Tighten connecting rod nut in two steps, with tightening moment of 29N.m. Mark at the foreside of nut end, and then rotate 90° to further tighten each nut. Crankshaft should be flexible to rotate without ja mming phenomenon. Axial and radial clearance of connecting rod should conform to requirements.

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ZG24 6.4 Cooling system Cylinder body of ZG24-type gasoline engine adopts forced water cooling circulation with a thermostat fixed at water entrance. As shown in drawing. Keep adequate coolant in the water tank. If using antifreeze, please mix according to instructions of antifreeze. Due to thermostat at water entrance, for the first time, add or replace coolant fully. Add more after generator

running until water level is stable.

Examine quality of coolant whether it is clean, oil stain. Change if necessary. Examine sealing condition of coolant system.

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ZG24 Examine and adjust tightness of fan belt. Press in the middle of belt  between AC generator and water pump with 98N pressure. used belt is 7 to 8

mm, and new 5 to 7

Bending of

mm.

Ensure that groove of fan belt and belt wheel is in good joint. As shown

in the drawing.

Examine thermostat. 88℃

～

76℃

Temperature of starting valve: 88℃～76℃ Lifting height of valve: over 8mm at 88℃

If temperature of starting valve rises or closing state doesn’t conform to regulations or requirements, should replace thermostat. Examine water pump. Examine status of water pump and timing sprocket room about crack or

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ZG24 hurt of joint line, and examine whether water pump bearing rotates flexibly and there is noise.

6.5 Lubricating system 6.6 Key points to mechanism Lubricating mode is fully filtering combined pressure & splashing. Lubricating oil pump is rotor type, and internal and external rotors installed in sprocket room are directly driven by damp crankshaft pulley. Main oil duct is installed in cylinder body, through oil duct, main axis, journal of connection-bearing and camshaft bearing (there is oil line to cylinder body) are lubricated; sprocket, chains and tightening mechanism are lubricated by oil injector in main oil duct; valve tappet, valve, bore hole, piston pin and pinholes and so on are lubricated by splashing. Oil pump of gasoline engine is powder metallurgical oil pump with internal and external rotors. Power is conveyed to crankshaft pulley by crankshaft rotating, and then conveyed to oil pump by crankshaft pulley.

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ZG24 Internal rotator of oil pump stirs external rotator to make it move eccentric motion, which is attributed to difference of volume and pressure of working space. Oil will be extracted from oil pan to working room of oil pump by negative pressure produced, while positive pressure will push oil to main oil duct. If there is fault in oil pump: 1. if foreign matters exist and oil pump is  ja mmed, camshaft and distributor block tooth will be damaged; 2. when oil  pressure is not rather little, it will cause each motive part of engine makes dry friction and the complete machine break out.

Oil filter: engine works in a fairly clean lubricating condition. If oil is dirty, it will cause deterioration of lubricating conditions of motive parts, or even damage of accessories. Oil filter is a device of filtering oil, which can filter out unclean oil. Oil-break alarm is a pressure transducer, whose sensing source is set in oil duct. When oil pump is working, in oil duct, there should be lubricating with certain  pressure ensuring every component of engine in normal lubricating condition, and which is sensed by oil alarm. In general condition, after starting engine,

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ZG24  pressure of lubricating oil in duct will rise to push the slice in alarm. Meanwhile, cut off, and if the driver sees that the indicator lamp is off, he can judge that the lubricating condition of each components of engine is in normal condition. Key points of assembly

1) As shown in the drawing, when applying sealant on installation face of bottom cover, should notice that diameter of applying sealant is about 3.5

mm, and the sealant should be even and

continuous.

6.7 Key points of admission and exhaust system structure Functions of inlet manifold include distributing air, fuel, oil air of crankcase ventilation and waste air of EGR evenly to each cylinder, and improving coefficient of charge by shape and length of inlet manifold and voltage regulation chamber. Function of exhaust manifold is to gather the waste air discharged from each cylinder of engine to lead it into exhaust main. Ensure smooth, even admission and high efficient charge by adopting aluminum alloy and long independent air duct of each cylinder; exhaust pipe is steel pipe and has the properties of excellent thermal stability and liability, and optimum designed structure is good for avoiding exhaust interference of cylinders and decreasing interference of exhaust pressure wave.

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