4y operation manual mdn-18s

4Y Gas Engine Operation Manual

MPS Operation Manual of 4Y Gas Engine

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Contents

Chapter 1 Technical Characteristics of Gasoline Engine ....................................................................... 3 1.1 Technical Specifications.................................................................................................................... 3 1.2 Performance Parameters.................................................................................................................... 4 1.4 External Characteristic Curve, Load Chain Curve, and Universal Characteristic Curve for 491Q (4Y) ......................................................................................................................................................... 5

Chapter 2 the Usage of gasoline Engine .................................................................................................. 7 2.1 The Engine Inspection before Start ................................................................................................... 7 2.2 The Start of Engine............................................................................................................................ 7 2.3 Check Engine during Running .......................................................................................................... 7 2.4 The Power-off of Engine ................................................................................................................... 8

Chapter 3 Operation and Maintenance of Gasoline Engine .................................................................. 8 3.1 Operation Caution ............................................................................................................................. 8 3.2 Break-in of Gasoline Engine ............................................................................................................. 8 3.3 Maintenance of Gasoline Lubrication System .................................................................................. 9 3.4 Maintenance of Engine Cooling System ......................................................................................... 10 3.5 Maintenance Cycle.......................................................................................................................... 10

Chapter 4 Engine Configuration, Maintenance and Adjustment ......................................................... 11 4.1 Cylinder Head ................................................................................................................................. 12 4.2 Cylinder Block ................................................................................................................................ 17 4.3 Connecting Rod Unit....................................................................................................................... 21 4.4 Air-distribution system.................................................................................................................... 24 4.5 Fuel Supplying System.................................................................................................................... 29 4.6 Lubricating System ......................................................................................................................... 31 4.7 Cooling System ............................................................................................................................... 33 4.8 Electrical System............................................................................................................................. 34 4.9 Crankcase Vent Unit ........................................................................................................................ 40 4.10 Clutch and Operating System........................................................................................................ 41

Chapter 5 Trouble and Trouble Shooting ................................................................................................ 43 5.1 The Engine Is Difficult to Start ....................................................................................................... 44 5.2 Malfunction with Engine Accelerating............................................................................................ 45 5.3 Engine Power & Torque Not Enough.............................................................................................. 45 5.4 Engine Back Fire and Deflagrating ................................................................................................. 46 5.5 Engine Unstable at Idle Speed......................................................................................................... 47 5.6 Abnormal Noise from Engine.......................................................................................................... 48 5.7 Fuel Consumption Too High ........................................................................................................... 48 5.8 Oil Consumption Too High ............................................................................................................. 49 5.9 Engine over Heating........................................................................................................................ 49 5.10 Oil Pressure Too Low.................................................................................................................... 50 5.11 Firing Not Stops after Ignition Key Switches Off ......................................................................... 51

Chapter 6 Engine’s Preservation and Depreservation.......................................................................... 51 6.1 Long Storage of Engine................................................................................................................... 51 6.2 Start Engine after Long Storage ...................................................................................................... 52


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Preface

This instruction gives the technical data of 4Y gasoline engine, which are designed and

manufactured by our company. It includes the main technical parameters of these engines, and

their operation, maintenance, check, adjustment and malfunction analysis, it can be used for the

people who operate and maintain the engines.

4Y gasoline engine have strong power, good fuel economy, low emission, small volume, light

weight and compact structure with the new-type silencing design and air valve clearance

automatic adjustment system, which greatly decrease the noise, they are ideal power source.

As most of the components of 4Y and their model are general utility, the instruction is suitable

for other types of engines. Please be noticed that there is possible difference between the content

and the real structure because of the continuous innovation of the engines structure. They will be

updated in the new revisions. Our new type 4Y and their innovated gasoline engines or good for domestic and overseas market benefit to their excellent power, reliability and fuel economy.


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Chapter 1 Technical Characteristics of Gasoline Engine

1.1 Technical Specifications

Model 491Q(4Y)

Type Line, 4-stroke water-cooling

Cylinder 4

Bore*stroke 91*86mm

Shape of combustion chamber Cuneiform

Type of cylinder liner no liner

Total displacement 2.237L

Average speed of piston 13.19m/s

Compression ratio 8.8

Crank axle rotation direction Left rotation

Ignition angle 8-13º 750r/min

Ignition order 1-3-4-2

Inlet valve open 15°

Inlet valve close 53°

Exhaust valve open 53°

Exhaust valve close 13°

Lubrication model Force-feed splash

Total volume of engine oil (full in dry) 4.2L

Cooling model Circulated pressed water cooling

Without heater 7.9L

With front heater 9.1L

With front and rear heater 10.1L

Outside size(L*W*H) 750*552*625 mm

Net weight ≤150kg

P/N performance marked in left side of cylinder block


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1.2 Performance Parameters

Model 491Q(4Y)

Rated torque/ speed 68kw/4200-4600r/min

Max torque /speed 177N.m-2800-3200r/min

Lowest fuel consumption 285g/kw.h

Oil consumption ≤2.0g/kw.h

Compression pressure/speed 1226kpa-250r/min

On rated power 793.0kpa

On max torque 983.0kpa

Power per liter 30.40kw/L

Mass density 2.25kg/kw

1.3 General Technical Requirement

Fuel code Leadless gasoline 90 SH0041-93

Exhaust temperature(core pipe) ≤740

Engine oil pressure

At idle speed ≥29.4kpa

At 2000±50r/min ≥170kpa

At 3000±50r/min 245.2-490.3kpa

Max temperature of engine oil ≤110

Outlet temperature of coolant 85-105≤115 higher load

Coolant code good glycol coolant

Opening pressure of radiator cover 73.6-103.0kpa

In take pipe vacuum speed ≥76kpa

Fast idle speed 2600±100r/min

Idle speed 750±50r/min

Voted speed 4200-4600r/min

Air valve clearance 0

Sparking plug electrodes clearance 0.8-1.0mm

Fit new belt 5-7mm

Fit used belt 7-8mm

Forward chain looseness under 98N

Crankshaft rotation moment ≤30N.m


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Moment in fastening part

Cylinder head-cylinder block 88N.m

Rock arm axle-cylinder head 25N.m

In take/exhaust pipe-cylinder head 49N.m

Sparking plug –cylinder head 18N.m

Forward chain/camshaft 90N.m

Connecting rod-cover 49N.m

Crankshaft belt wheel bolt 108N.m

Flywheel –crankshaft 83N.m

Other screw fasteners

M6 8N.m

M8 18N.m

M10*1.25 39N.m

M12*1.25 71.5N.m

1.4 External Characteristic Curve, Load Chain Curve, and Universal

Characteristic Curve for 491Q (4Y)

1.4.1 Spare part of gasoline engine

Carburetor double cabinet separated downward

Gasoline pump mechanic filmed

Gasoline filter paper filter

Engine oil pump cycloid rotor type

Water pump centrifugal

Warmth saver Open at 82

Fan 7 leaves or 5 leaves

Sparking plug type F6RTC F7RTC

Specification M14*1.25

Electricity distributor

Type contacted non contacted

Electric contact clearance 0.45±0.05mm 0.30±0.05mm

Capacitor 0.25uF

Alternator 12V 65A 12V 90A

Starter 12V 1.4kw

Ignition coil 12V


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1.4.2 Dimension tolerance of the main components

Standard size Line Part

name

Contain site Contained site Tolerance

Max wear

Tolerance

+0.01 -0.055I Φ91

-0 Φ91

-0.065

+0.02 -0.045II Φ91

+0.01Φ91

-0.055

+0.03 -0.035

1 Cylinder

hole and

piston

bottom

axle(24m

m to

top)(by 3

line)

491Q

4Y

III

Φ91 +0.02 Φ91 -0.045

0.055-0.075

+0.036 +0 2 Con rod shell

hole and axle

neck by 3 line

Φ48 +0.02 Φ48 -0.015

0.02-0.051 0.10

+0.038 0 I Φ58

+0.022Φ58

-0.015

0.022-0.053

+0.037 0 II Φ58

+0.022Φ58

-0.015

0.022-0.052

+0.036 0

3 Crankshaft main

bearing hole and

neck

II Φ58

+0.022Φ58

-0.015

0.021-0.051

0.10

+0.04 -0.025I Φ46.5

0 Φ46.5

-0.041

+0.04 -0.025II Φ46.25

0 Φ46.25

-0.041

+0.04 -0.025III Φ46

0 Φ46

-0.041

+0.04 -0.025IV Φ45.75

0 Φ45.75

-0.041

+0.04 -0.025

4 Camshaft bearing

hole and neck

V

Φ45.5

0 Φ45.5

-0.041

0.025-0.081 0.10

+0.016 +0.0065 Piston pin hole

and pin

Φ22

+0.010Φ22

+0.003

0.004-0.013


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Chapter 2 the Usage of gasoline Engine

To operate the engine properly will not only ensure the engine to run well but also for a long time.

2.1 The Engine Inspection before Start

Check the following items before starting the engine

2.1.1 Check the volume and leakage of cooling water and make sure that the water pipes are

fastened well to it and fan belt is properly tens.

2.1.2 Check the volume of engine oil, its oil scale should between 2/4-3/4, adding more if it is

inadequate.

2.1.3 Check the fuel tank to make sure that there is enough gasoline and that all pipes and

connections are properly fastened.

2.1.4 Check whether the electric system is correct and safe, the storage battery is sufficient or not.

2.2 The Start of Engine

2.2.1 Engage the neutral shift and press the clutch in order to reduce the load when starting the

engine

2.2.2 Switch the ignition key to start the engine

2.2.3 When engine starts, release the key and the key automatically to ignition position, when

engine is cold started, engine will run at fast idle speed in the beginning and will run at normal idle

speed when engine coolant temperature raise.

2.2.4 If the engine fails to start for several times, check it and determine the cause.

2.3 Check Engine during Running

2.3.1 Whether there are noises like knocks of other abnormal noises.

2.3.2 Whether there is burning smell which may attribute to overheat of starter or other elements

2.3.3 Whether there is any leakage from cooling and lubrication systems.

2.3.4 Whether the meters of oil pressure, water temperature, electric current, gasoline and the like

can work.


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2.4 The Power-off of Engine

Before stop the engine which is running with big load, run it at lower speed for 2-3 minutes and

then switch off the engine, in order to cool down the engine, otherwise some parts may become

deformed due to sudden cooling down of the whole engine.

In freeing season, add antifreeze to the cooling water and make sure it does not freeze if the

car is parked in an open area, otherwise drain out all the coolant. Open the both cap: on the top of

radiator and bleeder cock at the bottom. Do not leave until all the coolant is drained out. It is better

to restart the engine to run for half a minute at low speed in order to remove water stored in water

pump which may freeze the inlet.

Chapter 3 Operation and Maintenance of Gasoline Engine

3.1 Operation Caution

3.1.1 Maintain according to the method and regulations in this manual when operation.

3.1.2 Inspect the polarity of ground strap connection. This gasoline engine connect with cathode

one.

3.1.3 New engine must be ran-in as required. It is not permitted to increase load abruptly.

3.1.4 Keep normal water temperature at 85-105. At medium speed, the normal engine oil’s

pressure should be 245-490kpa.

3.1.5 The fuel must be 90# vehicle gasoline

3.1.6 It is not permitted to stop the engine after running 3-5minuted of low speed.

3.1.7 Before drain the cooling water, water temperature of coolant system must be decreased.

Open the radiator cover first (otherwise the hot water will spout nod scald easily), then turn on the

water valve at bottom of radiator and water switch at left front side of cylinder block.

3.2 Break-in of Gasoline Engine

The gasoline engine’s life related with working condition of newly running. The new engine on the

vehicle should run 2500km on road work 50 hours on the test bench. Newly running of gasoline

engine in vehicle should follow:

3.2.1 Check if engine oil, coolant, gasoline is enough, of not, must fill them, if leak exist, eliminate


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leakage.

3.2.2 Running in vehicle should be on the cement of asphalt road, try not to be on other road

especially on sand beach road.

3.2.3 New engine specifications of break-in refer to following table:

Mileage(km) Load Speed

0-200 25% of rated load ≤3000r/min



1501-2000 Rated load ≤4200r/min

3.2.4 When reaching following mileage (km), should change engine oil:

500 1,000 1,500 2,500 at 2,500kw should change engine oil collector

3.2.5 Fastening cylinder head bolt

To prevent cylinder head gasoline leakage at air water, when running at 300km and 1000km,

check the fastening moment of cylinder head bolt with the torsion spanner. Its fastening moment is

88N.m.

3.3 Maintenance of Gasoline Lubrication System

3.3.1. Engine oil

Engine oil viscidity: SAE10w-30(winter), 15w-40(summer), or choose the brand of viscidity in the

with environment temperature. Engine oil quality level (as per American petrol Academy): APZ, SE,

SF. SG or higher level engine oil.

After new engine running of 2500km or normal running of each time after 5000km. engine oil

must be changed. Expanse life of engine is ensured only when maintained and change oil as per

regulation. The recommended engine oil is:

Imported shell brand, American Mobile, etc

Note: different brand engine oil can not mix to use

3.3.2 Oil changes

Except new running of engine, the engine oil should be changed according to regulated mileage.

Normally change each 5000km on asphalt road.

Drain the engine oil from oil tank when engine is still hot. Otherwise when engine become cool,

some impurity will stay in the bottom of oil tank, hard to flow off wit the oil.

If a lot of impurity exists in oil tank, clean the engine lubrication system with light spindle oil. It

is absolutely prohibited to clean with gasoline or kerosene.


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When cleaning internal of engine, fill up 3.5-4.0L light spindle oil into oil tank, tear off all

sparking plug, rotate crankshaft 2-3minutes, and then drain cleaning spindle oil entirely, Add new

engine oil into tank as per regulation.

3.3.3 Change engine oil filter

Change after newly running after 2500km, later change new one after running 10000km each.

3.4 Maintenance of Engine Cooling System

There must be enough coolant inside cooling system to ensure normal engine work well, so

please check it before using vehicle each time. Add coolant of clear soft water, if not enough. It is

prohibited to use hard water composing lots alkali of mineral material, bad liquid as well.

3.4.1 Change coolant: choose good glycol base coolant, and mix as per suppliers specifications.

Change coolant each time after running 20000km, as per is the order as follow:

(1)Open the radiator cover and radiator water switch, drain coolant

(2) Dismantle water tank, drain coolant

(3)Open the water switch of cylinder block’s left side, drain coolant

(4)After drain all the coolant, close and fasten the water switch of radiator and engine

(5)Add new coolant

(6)Fasten radiator cover

(7)Start engine and check if there is leakage

(8)Check the coolant and add according

3.4.2 Replace and adjust the fan belt The fan belt is moving electricity generator, water pump and cooling fan. Low tensility or other faults will make engine over hot of generator less output. When belt is damaged, check, adjust and change as follows:

(1) Stop engine loosen the adjustment belt, push the

generator outward to make the belts, tensility reach the valve

in regulation.

(2)Measure fan belts tensility load 98N power on the middle of the belt between alternator and

cooling fan, the belt deformation valve should be: New belt: 5-7mm, used belt:7-8mm

(3)Fan belt should keep good status. If it can not work normally, replace the fan belt.

3.5 Maintenance Cycle

Please accord to the following procedure to assure engine work normally.


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3.5.1 Everyday maintenance.

(1) Check gasoline, cooling water, and height of coarse oil surface. Please add if necessary.

(2) Clear ash and spilling electrolyte on the accumulator to assure small vent-hole expedite. Add

distilled water betimes if electrolyte is lacking.

(3) Checking whether there is oil leakage or water leakage after starting engine.

(4) Checking whether joints of high-voltage and all the wires are loose.

(5) After starting engine, check whether it can run normally. Assure instruments work normally.

3.5.2 Season maintenance.

(1) Please add anti-freeze in winters.

(2) Change concentration of electrolyte according to seasons.

Chapter 4 Engine Configuration, Maintenance and Adjustment

To ensure engine’s performance, repair and maintenance are necessary.

To repair and adjust the engine correctly, please use the suitable equipments and special tools

following the key points below.


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4.1 Cylinder Head

4.1.1 To prevent from gasket air or water leakage, please inspect the torque of cylinder head bolts

after 500km and 2,000km running for a new vehicle.

The fastening torque is 88N.m (9kgf.m) (No. 1-10) and 19N.m (1.95kgf.m) (N0. 11-13).


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4.1.2 Please follow the sequence in the picture to disassemble the rocker arm shaft assy, loosen

the shaft’s bolts and nuts by 2-3 times, to avoid of breaking the shaft or damaging the bolts or nuts.

Please follow the reverse sequence in the picture to install the rocker arm shaft assy., tighten the

shaft’s bolts and nuts by 2-3 times with torque 24N.M (2.4kgf.m)

4.1.3 Loosen the cylinder head bolts 2-3 times gradually with reverse sequence as 4.1.1 while

disassembling the cylinder head. Otherwise it may cause the cylinder head out of shape.

4.1.4 To keep from damaging the cylinder head, cylinder block and cylinder gasket while scraping

off the stuffs on these parts and to avoid of cylinder gasket stuffs dropping into lifter holes, cooling

water passage hole and bolts hole.

4.1.5 Cylinder gasket can be used once only. Please replace the gasket while reassembling the

cylinder head.


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4.1.6 Inspect the breaks on cylinder head and measure the flatness degree. The numeric value

should be under 0.15mm. The flatness degree of manifold interface should be under 0.12mm.

Please repair or change the cylinder head if the numeric value is up.

4.1.7 Inspect the fit clearance between valve pushing rod and valve guide. Please replace the

valve and valve guide if the intake valve clearance exceeds 0.1mm and exhaust valve clearance

exceeds 0.12mm. The standard clearance between valve pushing rod and valve guide should be

0.025-0.060mm for intake valve and 0.030-0.065mm for exhaust valve.

4.1.8 Inspect the valve conical surface if it is unevenness or if it has grooves or carbon deposition.

Please modify the valves with 44.5°conical angle. Please to be sure don’t grind too much as you

may damage the valve.

Change the valve if the thickness is less 0.5mm (intake valve) and 0.8mm (exhaust valve)

after grinding.

Using grinding wheel to grind the valve rod to no more than 0.5mm if there’s scratch on it. The

standard length of total intake valve is 108.2mm, exhaust valve is 108.5mm.


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4.1.9 Inspect the abrasion level and scratch on the valve seat. If necessary, please modify the

valve seat. Firstly please inspect the abrasion level of valve guide and change it if the valve seat is

over abrasion. Then grind the valve seat with grinding wheel as the numeric value shown in picture.

The strip width between valve seat and valve conical surface is at the range of 1.2-1.6mm. The

strip should be in the middle of conical surface. To grind it with 30°or 45°grinding cutter if it is up or

with 60°or 45°grinding cutter if it is down.

Finally, grind the valve and valve seat with grinding cream to make it fit tightly without leakage,

and clean the valve seat, valve and inner hole of valve guide.

4.1.10 Inspect the free length of valve spring at 47±0.5mm.

Check the uprightness degree of the valve spring using right-angle ruler and flat board. To be

sure the degree should be less than 2mm, please change it if it exceeds 2 mm. measures the

valve spring with spring tester. The elasticity while installing at 40.6mm should be 282.5N (28.8kgf).

If it is less than standard please change.


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4.1.11 Measure the gap between rocker arm and rocker arm shaft. The standard gap should be

0.013-0.041mm, maximum is 0.08mm. If the gap is more than the maximum, please change the

rocker arm and rocker arm shaft.

Check the direction of back rocker arm shaft and assemble the rocker arm & spring with

special tools according to the picture.

If the contact surface of rocker arm and valve is abrasion, please grind it using whetstone or

change it.


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4.2 Cylinder Block

4.2.1 Inspect the breaks on cylinder block and measure the flatness degree. The numeric value

should be under 0.05mm. If the flatness degree exceeds 0.05mm, please grind or change it.


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4.2.2 Inspect the inner bore of cylinder block and measure the real dimension of the inner bore

with cylinder-measure gauge from up to down.

The maximum dimension should be

Piston diameter Maximum cylinder inner diameter(mm)

Standard 91.24

Enlarged 0.50mm for repairing 91.74



If any inner diameter is more than the maximum, please re-bore it.

4.2.3 Please re-bore it if the cylinder wall is seriously scratched, burned or over worn. Select the

most worn cylinder to confirm the size of enlarged piston while re-boring.

The piston dimension is stamped on the top of the standard piston which is fixed on the engine.

The specification is as following

Line Piston diameter(mm)

1 90.938-90.948

2 90.948-90.958


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3 90.958-90.968

See the picture to measure the piston diameter.

The enlarged piston dimension is as 0.50, 0.75 and 1.00. See below

Piston dimension Piston diameter(mm)

Enlarged 0.50mm for repairing 91.438-91.468



Fit clearance between piston and cylinder is 0.052-0.072mm

4.2.4 The main bearings are not exchangeable and please don’t install in reverse direction. To

avoid installing in reversal, the order no and the mark TOWARDS FRONT are stamped on the

main bearing.

4.2.5 It is fixed with crankshaft thrust washer gasket at the side of third main bearing seat and the

side of third main bearing cover. Make sure the bush side with oil groove toward-out and don’t fix it

in reverse direction.


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4.2.6 There’s oil grooves and oil hole on cylinder main bearing. Please don’t fix it in reverse

direction.

4.2.7 Take off the valve lifter by a metallic wire shown in picture and keep it in sequence to make it

easy to reinstall.

4.2.8 Inspect the crankshaft clearance with standard 0.02-0.22mm. If the crankshaft exceeds

0.3mm please change the crankshaft thrust bush.

The thickness of crankshaft thrust bush is as below.

Standard 2.450-2.490mm

Enlarged 0.125mm for repairing 2.575-2.615mm

Enlarged 0.250mm for repairing 2.700-2.740mm

4.2.9 Inspect the fit clearance between crankshaft journal and main bearing with standard

0.020-0.051mm. If the clearance exceeds 0.10mm, please change the bearing or crankshaft.

Please to be sure the standard main bearing is accordance with the dimension of main bearing

hole which is stamped on right rear cylinder block undersurface (1st to 5th main bearing hole from


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front cylinder block). 3 dimensions of main bearing are corresponding with the marks 1, 2, and 3.

The standard diameter of crankshaft journal is φ57.985-φ58.00mm. The maximum conicity

and ovality is 0.02mm.

Fastening torque of main bearing bolts is 78N.m (8kgf.m).

4.2.10 Inspect crankshaft bending degree

Put front and rear crankshaft journal on the V-shape metal, measure the bending degree in

the center of crankshaft journal using dial indicator. The maximum bending degree is 0.06mm. If it

exceeds the maximum, please change the crankshaft.

4.3 Connecting Rod Unit

4.3.1 There’s mark on connecting rod and connecting rod cap, don’t fix it exchangeable. The

connecting rod and the semi-circle protrusion on connecting rod cap must be at the same side

towards engine front.


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4.3.2 Check the gap between big end of connecting rod and crankshaft at standard 0.160-0.312mm. Chang it if it is out of standard. Check the fitting clearance between crankshaft/connecting rod journal and connecting rod bearing at standard 0.020-0.051mm, maximum is 0.10mm. Change it if it exceeds the maximum. The standard dimension is corresponding with the size which is stamped on the side connecting rod or side connecting rod cap. 3 size for standard bearing as marked 6, 7 and 8. Standard diameter of crankshaft/connecting rod journal isφ47.985-φ48.00mm. The maximum conicity and ovality is 0.02mm.

4.3.3 Install the connecting rod corresponding with the marks on cap using torque wrench with 49N.m (don’t move the crankshaft at this moment).

4.3.4 Inspect the bending degree using connecting rod adjuster with standard no more than 0.05mm at length 100mm. Please adjust or change it if it exceeds the maximum.


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4.3.5 Inspect the abrasion of piston or piston ring groove. Please change it if necessary. Please change piston ring as you change the piston. Side gap of piston ring is 0.03-0.07mm. Change it if it is out of the standard. The split gap of piston ring is as below. 1st ring 0.027-0.039mm 2nd ring 0.040-0.055mm Oil ring 0.20-0.70mm Change it if it is out of the standard.

4.3.6 To avoid fixing in reversal direction, the small round hole in combustion chamber must be towards to the engine front. The open split must cross each other while installing the 3 rings in ring grooves. See picture.

4.3.7 The marks “1T” on 1st ring and “2T” on 2nd ring must be towards to cylinder head while installing.


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4.4 Air-distribution system

4.4.1 Inspect the abrasion of rocker arm and rocker arm shaft. Change it if it is over abrasion. The gap between rocker arm and rocker arm shaft is 0.013-0.041mm, maximum is 0.08mm. Inspect the abrasion of contact surface between rocker arm and valve rod. Change or grind it if it is over abrasion.

4.4.2 Inspect the fitting clearance between hydraulic lifter and lifter hole in cylinder at standard 0.012-0.056mm, maximum is 0.1mm. Change it if it is out of standard or maximum. To inspect the lifter: put lifter in oil, press the lifter using pushing rod to let out the air in lifter, then


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the oil is filled inside lifter. Press the lifter seat again using pushing rod, if it is difficult to press down, it shows the lifter is good to use. If it is easy to press down, it shows the lifter is leakage, please change it. Otherwise the rocker arm hit the valve as PA while engine running. Let out the air inside lifter to fill with oil before the lifter is fixed on the engine. The lifter is a precise mechanical part matching with the lifter seat. Not allowed to exchange or disassemble. Clean it with clear oil.

4.4.3 Inspect the pushing rod if it is damaged or bent. Change it if necessary. The maximum bending degree of pushing rod is 0.3mm. Make the oil passage of inner pushing rod free instead of blocking. 4.4.4 Inspect the tension degree of timing gear at 98N (10kgf) with spring balance. Check the maximum gap of chain tension unit at 13.5mm. Change timing gear or timing chain if it is out of the maximum.


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4.4.5 Inspect the length of timing chain Measure it as shown in picture. The maximum length of chain is 291.4mm while adding force 49N (5kgf) on the spring balance. Change the chain if it exceeds the maximum length.

4.4.6 Inspect the diameter of sprocket Measure the diameter of sprocket (with chain) using slide gauge. Minimum length of sprocket (with chain) is as below. Crankshaft timing sprocket: 59mm Camshaft timing sprocket: 114mm. Please change the 2 sprockets and chains if the diameter is less than the minimum.

4.4.7 Inspect the abrasion of plug seal on chain tension unit. Measure the minimum thickness of plug seal at 12.5mm with slide gauge. If the thickness is less than the minimum, change the plug seal.


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4.4.8 Inspect the abrasion of damper on chain with slide gauge at minimum 5mm on rubber damper. Change it if it is less than the minimum. 4.4.9 Install camshaft thrust plate Fix the camshaft thrust plate with 2 bolts and fasten with torque 18N.m (1.85kgf.m). Please note the installing direction shown in picture.

4.4.10 Inspect the bending degree of camshaft Put the front/rear camshaft journal on v-shape metal. Measure the bending degree of centre camshaft journal with dial indicator. Maximum bending degree is 0.06mm. Change it if it exceeds the maximum.

4.4.11 Inspect the protuberance degree of cam. First check the abrasion of cam surface. Please change it if necessary. If the abrasion is not serious, grind it using whetstone. Measure the protuberance length at the big head bevel of cam. The minimum protuberance length is as below. Intake cam: 38.26mm Exhaust cam. 38.27mm If the length is less than the minimum, please change the camshaft.


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4.4.12 Inspect the fitting clearance between camshaft journal and cam shaft at the standard 0.025-0.081mm, and maximum at 0.1mm. if the fitting clearance exceeds the maximum, please change the crankshaft or camshaft.

4.4.13 Inspect the gap of camshaft. Fix the thrust plate and camshaft timing sprocket on camshaft and fasten the screw with stated torque. Measure the fitting clearance between thrust plate and front camshaft thrust surface with standard 0.07-0.22mm, the maximum is 0.3mm. If the clearance exceeds the maximum, please change the thrust plate or camshaft.

4.4.14 Fix the timing sprocket and timing chain. 1. The mark of small hole towards to engine front while installing camshaft thrust plate. 2. Turn the crankshaft, and make one piston position at the upper dead center (crankshaft moon


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key towards up). Camshaft moon-key up-towards corresponding with the small hole mark on thrust plate. 3. Fix the timing chain onto the camshaft sprocket and crankshaft sprocket making the white strip mark on chain towards to the small hole mark on the 2 sprockets.

4.4.15 Mounting clearance of crankshaft position sensor. See 4.8.3.

4.4.16 Put some lubricant to the hole of seat while fix the chain tension unit.

4.5 Fuel Supplying System


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1. Natural gas flow diagram

The

gas inlet is connected with the natural gas pipeline, to connect the gas inlet of solenoid valve and

natural gas pipeline with dedicated gas pipeline, the gas outlet port of solenoid valve is connected

with Maxitrol RZ series zero pressure regulator, the maximum inlet gas pressure of which is 1psi

(68mbar), and the outlet gas pressure is nearly zero, according to the requirements, the outlet

pressure (-2.5mbar~3.75mbar) can be adjusted by turning adjusting bolt. Natural gas enters into

the inlet port of the speed governor after regulated by a zero pressure regulator. The power

regulation valve is installed in the inlet port of the speed governor to regulate the gas intake flow to

change the air fuel ratio. The system has following advantages:

♦ By solenoid valve and zero pressure regulator’s regulation, the outlet pressure of gas is zero

or negative, which makes engine easy to start, more stable and reliable.

♦ The speed governor is a mix of Venturi mixer and throttle body, easy to install and

space-saving.

♦ The speed regulation is realized by the speed governor’s butterfly valve that controlling

throttle valve, the built-in throttle return spring can ensure to close the throttle valve when

failure occurs.


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2. LPG flow diagram

It adopts IMPCO’s solenoid valve and vaporizer, to connect the LPG tank and solenoid valve filter

with gas copper tube, to install the vaporizer vertically, to fully vaporize the LPG by internal

circulating water. The gaseous fuel enters into the inlet port of the speed governor after regulated

by a zero pressure regulator. The power regulation valve is installed in the inlet port of the speed

governor to regulate the gas intake flow to change the air fuel ratio. The system has following

advantages:

♦ By solenoid valve and vaporizer’s regulation, the outlet pressure of gas is zero or negative,

which makes engine easy to start, more stable and reliable.

♦ The vertical installation can effectively filter impurities in LPG, well avoid erosion of the

impurities to diaphragm and prolong the service life.

♦ The speed controller is a mix of Venturi mixer and throttle body, easy to install and

space-saving.

♦ The speed regulation is realized by the speed governor’s butterfly valve that controlling

throttle valve, the built-in throttle return spring can ensure to close the throttle valve when

failure occurs.

4.6 Lubricating System

4.6.1 Inspect the oil level

Check the oil level in oil sump and the level must be at the center between the L mark and L mark.

Check the leakage. If it is under the mark L, please add the oil to reach the F mark. The oil


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capacity is 4.2L.

4.6.2 Inspect the quality of oil.

Check and change it if the oil is bad, polluted or diluted by water, otherwise it will cause the

performance of the engine. Use SE 10W-3- or SE 15W-40 oil as the viscosity of oil shown in

picture. Please don’t mix the oil with other brand.

4.6.3 Inspect the pressure of oil. Inspect the pressure of oil while engine warming at the working temperature. At idle speed≥29kPa (0.3kgf/cm2) At 3000r/min 245-490kPa (2.5-5kgf/cm2)

4.6.4 Change the oil filter Take off the oil filter with special wrench. Put some oil on the oil filter seal; fix it on the oil filter seat and fasten the oil filter with special wrench. Please don’t reuse the oil filter as it is one time use.


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4.6.5 Inspect oil pump. As shown in picture, put a opener in oil pump and take the oil collector into oil sump. Turn the pump shaft in clock wise. The oil pour out from the hole. And block the hole with hand, thus it’s difficult to turn the shaft.

4.7 Cooling System

4.7.1 Inspect the cooling water in storage.

If it is lack of cooling water, add it. If you use antifreeze liquid, please mix it according to the

manual.

4.7.2 Fill full cooling water and start the engine. And stop the engine to fill full cooling water again

till the water level don’t change.

4.7.3 Inspect the quality of cooling water.

4.7.3.1 Change cooling water if it is dirty.

4.7.3.2 Inspect if the radiator cap and the filler choke are rusty.

4.7.4.1 Inspect the leakage of cooling system.

4.7.4.2 Inspect if the radiator and its hose are damage or out of shape.

4.7.4.3 Inspect if the hose clips are tight.

4.7.5.1 Inspect the belt fan and change it if necessary. 4.7.5.2 Inspect and adjust the tension degree of belt fan. Measure the center belt from alternator to water pump with torque 98N (10kgf). If the tension degree is out of the standard 7-8mm (5-7mm for new belt), please adjust it.


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4.7.5.3 Please to be sure good contact with belt pulley.

4.7.6 Inspect the thermostat.

Put thermostat into water and heat the water gradually, to check the opening temperature and

raising length of the valve.

Opening temperature of valve: 76

Raising length of valve: ＞8mm at 90

If the opening temperature rises, please change the thermostat.

4.7.7 Inspect the water pump

Inspect the water pump and timing sprocket if it has split damage and if the water pump gear runs

freely without noise.

Obverse if the cooling water leak out from the cooling water out hole as shown in picture.

4.7.8 Inspect if the silicone oil fan is leakage.

4.8 Electrical System

4.8.1 Inspect he spark plug

Take off the spark plug and clean it. Check if the spark plug electrode and thread are damaged.

Change it if necessary.

Spark plug type T4197J, F7TC M14×1.5


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Standard electrode gap: 0.8-1.1mm

Installing with torque: 17.64N.m (18kgf.m)

4.8.2 Inspect the distributor

Inspect ignition advance. Disconnect the vacuum tube and connect to vacuum ignition advance

diaphragm. Add vacuum and check the status of ignition advance. If the ignition advance doesn’t

work well, please repair or change it.

Inspect the regulator advance. Rotate ignition distributor with clockwise, and release it to check if

the ignition distributor returns quickly with counterclockwise.

Check if the ignition distributor is tight. 4.8.3 Inspect the distributor. Disconnect the distributor cap, ignition distributor and anti-dust cover. Measure the gap between signal rotor and coupling coil protuberance with standard 0.2-0.5mm. Adjust it if it is out of the standard. Inspect the coupling coil resistance with ohm gauge. Coupling coil resistance (cold): 420-550Ω (normal type) Integrative type: 200-250Ω Change it if it is out of the standard. Inspect the ignition coil resistance (integrative type) Measure the resistance of the 1, 2 terminals as shown in picture. The primary ignition coil resistance is 1.3-1.6Ω (cold). Measure the resistance of the 1, 3 terminals as shown in picture. The vice ignition coil resistance is 10.4-14Ω (cold). Change the coil if it is out of the standard.

4.8.4 Inspect the resistance of the 2 poles with ohm gauge. The primary ignition coil resistance is 1.3-1.6Ω (cold). Change it if it is out of the standard


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Measure the resistance between positive pole and high voltage cable. The vice ignition coil resistance is 10.7-14.5Ω (cold). Change it if it is out of the standard.

4.8.4 Inspect the high voltage cable. Take the rubber sleeve and put off the high voltage cable from spark plug. Please be careful don’t damage the conductor inside. Measure the resistance of high voltage at maximum 250,000Ω. Check the terminals if the resistance exceeds the maximum and change it if necessary.

4.8.5 Fix the distributor Adjust the 1st piston to the upper dead center. Rotate the fuel pump gear and make the concave groove mark towards to the position as shown in picture. Rotate the distributor gear and make the concave groove mark towards to the concave groove mark on driving gear. Insert the distributor with the distributor gear towards to the mark on fuel pump gear.


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4.8.6 Adjust the contactless distributor and ignition timing. Inspect the ignition advance angle with ignition advance tester at the engine speed 750r/min. The timing advance angle is 10°-14°at front upper dead center. Adjust the angle if it is out of the regulation. Loose the screw of distributor, rotate the distributor cover clockwise to advance the ignition timing. Rotate the distributor cover counterclockwise to delay the ignition timing. Fasten the screw with torque 1.85kgf.m. 4.8.6 Adjust the ignition advance timing of integrative distributor. Take off the vacuum from the front vacuum sub cavity and block it.

The adjust method is the same with above, but the ignition advance timing angle is 8°at front

upper dead center 4.8.7 Reinstall the vacuum tube to the vacuum front cavity box and recheck the ignition timing.


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The ignition timing advance angle is 18°-22°at front upper dead center at the engine speed 750±50r/min.

4.8.8 Starting system

Note: the following test must be finished within 3-5 seconds to avoid from the coils bursting out. 4.8.8.1 Take off the excitation coil from the connector. Connect the battery to the magnetic switch and check if the small gear moves towards out. If the small gear doesn’t work, please change the magnetic switch assy.


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Take off the negative pole from the connector and check if the small gear moves towards out. If the small gear returns inside, please change the magnetic switch assy.

Connect the battery and current gauge. Check if the starter moves stably with the small gear towards out and check if the current shown on Ampere gauge is under the standard. Standard current: ＜90A at 11.5V

4.8.9 Generating system


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Take off the cables from generator. connect the negative pole of current gauge to generator. connect the positive pole to generator. Connect the negative pole of voltage gauge to ground. Connect the positive pole to generator. Speed the engine from idle to 2000r/min, check the volume of current and voltage on gauge. Standard current: ≤10A Standard voltage: 13.5-14.8V If it is not at the standard, please adjust or change the regulator.

4.9 Crankcase Vent Unit

The engine is fixed coercive crankcase vent unit. To clear the mixture, the mixture inside the

crankshaft is blown to the intake manifold through the vent valve. It can avoid the fuel pollute the

oil, and avoid the waste mixture and vapour erode the part surface. Please don’t take off the

crankcase at anytime.

The crankcase consists of PCV valve, vent pipe connecting vent valve to the connector on

carburetor heat insolating plate, and short pipes connecting the valve cover to inlet pipe of air filter.

Avid the vent valve blocked. Not damaged connecting hose. No leakage.


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4.10 Clutch and Operating System

4.10.1 Disconnect the gear, gear cover and release fork. Take off the thrust and pull out the gear and gear cover together.

Disconnect the disc. And plate. Please make mark.

4.10.2 Inspect if the parts of clutch plate are damaged or abrasion. Measure the depth of the rivets at minimum 0.3mm.


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Check if the diaphragm spring is abrasion with micrometer. Maximum depth: 0.6mm Maximum width: 0.5mm Change the clutch plate assy. if necessary.

4.10.3 Install the clutch Fix the clutch plate on flywheel matching the fitting marks on flywheel and fasten the screws with torque 1.95kgf.m Check if the bottom of diaphragm is aligned with micrometer. Maximum gap: 10mm. Adjust it if the gap exceeds the maximum.


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Chapter 5 Trouble and Trouble Shooting

After the engine has run for long time, some parts of the engine will wear or be damaged, which

will cause its technical condition getting worse. When the technical specifications are not in the

limited range, it indicates the engine is in trouble. The failure should be resolved in time as soon as

it appears. If the engine works with malfunction, not only the power and economic capability will

decrease, but also operation performance will change, even the accessories will wear quickly and

the engine will be damaged.

For some failures, such as air existing in oil system, clog of filter, loose of belt and so on that

can be resolved after maintenance or adjustment. But for other failures, such as piston ring is

further worn, cylinder gasket is damaged and so on, which cannot be resolved by maintenance or

adjustment because of the limitation of the engine. The operator has to disassemble the engine or

change accessories to resolve these failures.

Notes:

(1) Usually failure is caused by inappropriate operation or missing maintenance. The operator

should check if the engine is operated according to the regulations and maintenance guide when

failure happening.

(2) Resolve failure in time. Firstly, find the reason of the failure. Then go to service station if the

engine needs disassembly.

(3) For complicated failures, the technician should perform the process with professional

instrument and equipment. If the clients are not qualified to adjust or maintain the engine, they

should go to service station.

(4) It is not allowed for the engine to work with "sickness". Engine working with "sickness" will not

only damage the parts and decrease the life span of engine, but also cause accident.

The following malfunction, cause and solution are for reference only.


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5.1 The Engine Is Difficult to Start

Malfunction & Cause Solution

1. Malfunction with Start System

(1) battery voltage weakness

(2) Battery loose connection

(3) Fuse cutting off

(4) Malfunction with starter

(5) Malfunction with ignition switch

1.

(1) Charge battery

(2) Tighten all connections

(3) Change fuse

(4) Change or repair starter

(5) Change ignition switch

2. Malfunction with Ignition System

(1) wrong ignition timing

(2) Coil(s) damaged

(3) Hi-voltage cable damaged or loose connection

(4) Low-voltage cable damaged or loose

connection

(5) Improper clearance of spark plug electrodes

(6) Wateriness of the spark plug(s) or carbon

deposit on the electrodes

(7) Insulator of the spark plug(s) damaged

(8) Distributor cap or contact (s) damaged

2.

(1) Readjust

(2) Replace coil(s)

(3) Replace hi-voltage cable or fasten

connection

(4) Replace low-voltage cable or fasten

connection

(5) Adjust clearance

(6) Dry or clear away the carbon deposit

(7) Replace the spark plug(s)

(8) Replace the distributor

3. Malfunction with Fuel-supplying System

(1) Over-rich gas mixture

(2) Malfunction with fuel pump

(3) No fuel supply to the carburetor

(4) Improper working of the choke valve of the

carburetor

(5) Idle speed solenoid valve not open

(6) Fuel over flow from the carburetor

(7) Fuel supply hose plugged

3.

(1) Make the gas mixture lean. Clean

the air supply system.

(2) Check or replace fuel pump

(3) Check the fuel supply system

(4) Adjust or repair the choke valve

(5) Check the idle speed solenoid valve

(6) Repair the float and needle valve

(7) Clean the hose


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5.2 Malfunction with Engine Accelerating


1. Malfunction with Carburetor

(1) Fuel level too low

(2) Gas mixture too lean

(3) Malfunction with accelerating pump

(4) Malfunction with power valve

(5) Piston of the power valve improper working

(6) Throttle opening not enough

1.

(1) Adjust the fuel level

(2) Adjust or repair carburetor

(3) Check or repair accelerating pump

(4) Check or repair power valve

(5) Replace the spring of the piston

(6) Adjust the connecting rod

mechanism


(1) Spark plug improper working

(2) Hi-voltage cable damaged

(3) Coil(s) damaged

2.

(1) Check or replace spark plug(s)

(2) Replace hi-voltage cable

(3) Replace Coil(s)

3. Malfunction with Engine

(1) Valve(s) leaking or damaged from burning

(2) Improper cylinder pressuring

(3) Cylinder gasket leakage

(4) Intake manifold leakage

3.

(1) Repair or change valve(s)

(2) Repair or change related parts

(3) Change cylinder gasket

(4) Inspect manifold and its gasket,

fasten the nuts

5.3 Engine Power & Torque Not Enough


1. Improper Compressing

(1) Valve(s) leaking

(2) Hydraulic lifter(s) improper working

(3) Valve spring weakness or damaged

(4) Cylinder head gasket leaking

(5) Piston rings sticking together or damaged

(6) Over wear of piston(s) or cylinder liner(s)

1.

(1) Grind the valve(s)

(2) Check or replace hydraulic lifter(s)

(3) Replace valve spring(s)

(4) Replace cylinder head gasket

(5) Replace piston rings

(6) Repair or replace related parts


(1) Improper timing

2.

(1) Adjust timing


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(2) Spark plug(s) improper working (2) Clean, adjust or replace spark

plug(s)

3. Improper Fuel Supply

(1) Dust in fuel tank

(2) Fuel supply hose plugged

(3) Fuel filter plugged

(4) Fuel pump improper working

(5) Fuel passage or carburetor metering bore

plugged

3.

(1) Clean or replace fuel tank

(2) Blow or clean the fuel hose

(3) Replace fuel filter

(4) Repair or replace fuel pump

(6) Dismantle or replace carburetor

4. Throttle Body Opening Not Enough Adjust the operating mechanism

5. Improper Gasoline Quality Follow the regulation on the gasoline

quality

6. Intake Manifold Leaking Check intake manifold and gasket

7. Leaking from Ventilation Valve of the

Crankshaft Chamber

Fasten the connection

8. Carburetor inlet air not enough

(1) Air filter plugged

(2) Throttle body opening not enough

8.

(1) Clean the air filter housing and

element

(2) Repair or adjust the mechanism

9. Engine Over Heating Find 5.9 for details

5.4 Engine Back Fire and Deflagrating



(1) Improper timing

(2) Loose connection

(3) Spark plug(s) improper working

(4) Improper spark plugs

1.

(1) Adjust timing

(2) Fasten connection

(3) Clean, adjust or replace spark

plug(s)

(4) Use the right spark plugs

2. Improper Air/fuel Ratio

(1) Gas mixture too lean

(2) Fuel supply system plugged

2.

(1) Clean and adjust carburetor avoiding

leakage

(2) Find 5.3.3 for details


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3. Malfunction with Valve System.

(1) Valve(s) leaking or pasted together

(2) Hydraulic lifter(s) in poor condition

(3) Valve spring(s) weakness

3.

(1) Grind or change valve(s)

(2) Change or clean hydraulic lifter(s)

(3) Change valve spring(s)

4. Cylinder Head in Poor Condition

(1) Carbon deposit in combustion chamber

(2) Cylinder head over heating and poor cooling

(3) Cylinder head damaged

4.

(1) Clear away carbon deposit

(2) Remove air inside the cooling

system

(3) Replace cylinder head

5. High-voltage Wires in Wrong Order or Wires

Damaged

Reconnect or change the wires

5.5 Engine Unstable at Idle Speed


1. Malfunction with Carburetor

(1) Malfunction with the metering bore

(2) Fuel passage or low speed fuel metering bore

plugged

(3) Needle valve in wrong position or leaking

(4) Choke valve not working

(5) Solenoid valve not open

1.

(1) Adjust idle speed screw

(2) Clean

(3) Clean, adjust or replace

(4) Check and repair

(5) Check solenoid valve

2. Air Leakage

(1) Intake manifold leaking

(2) Leaking from ventilation valve of crankshaft

chamber

(3) Loose bolts of carburetor

2.

(1) Check intake manifold or replace

gasket

(2) Fasten connection

(3) Fasten the bolts

3. Malfunction with Ignition System Find 5.1.2 for details

4. Malfunction with Valve System

(1) Air leakage from valve(s)

(2) Improper working with hydraulic lifter(s)

(3) Over clearance between valve stem & valve

guide

4

(1) Grind valve(s)

(2) Replace hydraulic lifter(s)

(3) Replace valve stem & valve guide

5. Air Leakage from Cylinder Head Gasket Replace cylinder head gasket


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6. Problem with Fuel Supply System Find 5.3.3 for details.

5.6 Abnormal Noise from Engine


1. Knocking Due to Early Timing 1. Adjust the timing angle

2. Problem with Hydraulic Lifter(s) 2. Check or replace hydraulic lifter(s)

3. Piston Pins too Loosing 3. Replace piston pin(s) or piston(s)

4. Over Wear from Piston(s), Piston Ring(s) and

Cylinder(s)

4. Check, replace or horning cylinder(s)

5. Over Wear from Bearing(s) of Connecting

Rod(s)

5. Check and replace bearing(s)

6. Over Wear from Main Bearing(s) 6. Check and replace bearing(s)

7. Over Wear from Crankshaft Thrust Washer Set 7. Repair or replace thrust washer set

8. Over Clearance Between Camshaft and

Camshaft Thrust Plate

8. Replace crankshaft Thrust Plate

9. Over Wear from Timing Chain and Timing

Pulley

9. Replace

10. Improper Working of Chain Tensioner 10. Replace Tensioner

11 Too Much Carbon Deposit in Combustion

Chamber of Cylinder Head

11 Clear away the carbon deposit

12. Gasoline Do Not Meet Regulation 12. Use the qualified gasoline

5.7 Fuel Consumption Too High


1. Fuel Leakage from the Fuel Supply Hose 1. Fasten connections & clips

2. Air Filter Plugged 2. Check or replace air filter

3. Problem with Carburetor

(1) Fuel level too high

(2) Idle speed too high

(3) Improper opening of Choke Valve

(4) Leakage from power valve

3.

(1) Check fuel level

(2) Adjust idle speed

(3) Check and repair choke valve

(4) Check power valve


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(5) Loosing bolts or metering bore

(6) Gasket damaged

(5) Replace bolts or metering bore

(6) Replace gasket

4. Problem with Ignition System

(1) Improper timing

(2) Malfunction with spark plug(s)

4.

(1) Adjust timing

(2) Check or replace spark plug(s)

5. Improper Compressing 5. Find 5.3.1 for details

6. Clutch skidding Check and adjust clutch

5.8 Oil Consumption Too High


1. Oil Leakage

(1) Oil discharge screw loosing

(2) Bolts of oil sump loosing

(3) Gasket of oil sump damaged

(4) Bolts of chain chamber loosing

(5) Sealing gasket of valve chamber damaged

(6) Oil seals of crankshaft damaged

(7) Bolts of oil pump loosing or gasket damaged

(8) Bolts of oil filter loosing or gasket damaged

1.

(1) Fasten oil discharge screw

(2) Fasten bolts

(3) Replace gasket

(4) Fasten bolts and replace gasket

(5) Replace gasket

(6) Replace oil seals

(7) Fasten bolts or replace gasket

(8) Fasten bolts or replace gasket

2. Piston Oil Rings Over Wearing or damaged 2. Replace piston oil rings

3. Over Wear of Pistons with Cylinders 3. Repair or change

4. Oil Seals of Valve Stem Damaged 4. Replace oil seals

5. Over Wear of Valve Stems with Guides 5. Replace valves & guides

6. Ventilation System of Crankshaft Chamber

Plugged

6. Check & clean

7. Long Time Engine Running at High Speed with

Low Load

7. Avoid long time engine running at

high speed with low load

5.9 Engine over Heating


1. Cooling Liquid Not Enough 1. Add enough cooling liquid


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2. Fan Belt Loosing or Damaged 2. Adjust belt tension or replace belt

3. Problem with Water Pump 3. Check or replace

4. Problem with Thermostat 4. Replace thermostat

5. Radiator, Cylinder Block, Cylinder Head and/or

Related Passages Plugged or Leaking

5. Clean, repair or replace parts

6. Problem with Silicon Clutch 6. Check or replace

7. Late Timing 7. Adjust timing

8. Oil Not Enough or Viscosity Too Low 8. Add oil or replace oil

9. Too Much Carbon Deposit in Combustion


9. Clean out the carbon deposit I

10. Exhaust System Plugged 10. Clean or replace related parts

5.10 Oil Pressure Too Low


1. Oil Leakage 1. Find 5.8.1 for details

2. Oil Not Enough or Viscosity Too Lean 2. Find 5.9.8 for details

3. Oil Temperature Too High 3. Cool down the engine and repair the

cooling system

4. Problem with Pressure Reducing Valve of Oil

Pump

4. Repair the valve

5. Problem with Oil Pump 5. Repair or replace oil pump

6. Oil Strainer Plugged, Oil Leaking from the

Connection

6. Clean and fasten connection

7. Oil Filter Plugged 7. Replace air filter

8. Problem with Oil Pressure Sensor 8. Replace oil pressure sensor

9. Problem with oil Pressure Gauge 9. Replace oil pressure gauge

10. Over Wear of Main Bushings and Crankshaft

Bearings

10. Replace bushings or bearings

11. Oil Leaking from Rocker Arm Shaft or Chain

Tensioner

11. Check and fasten


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5.11 Firing Not Stops after Ignition Key Switches Off


1. Engine Over Heating 1. Run the engine without load until

water temperature drops below 80 .

Then switch off the igniting key

2. Spark Plugs Over Heating 2. Choose the right spark plugs

3. Too Much Carbon Deposit in Combustion


3. Clear away the carbon deposit

4. Late Timing 4. Adjust timing

5. Problem with Carburetor

(1) Maladjustment of the idle speed or fast idle

speed

(2) Problem with solenoid valve for idle speed

5.

(1) Check and adjust

(2) Check or replace solenoid valve

Chapter 6 Engine’s Preservation and Depreservation

6.1 Long Storage of Engine

6.1.1 Discharge all the cooling liquid from the radiator and water pump

6.1.2 Dismantle battery

6.1.3 Make sure the engine in good condition and clean the engine

6.1.4 Pull out the spark plugs. Then inject about 30 grams of dry oil. Crank the engine for 15-20

revolutions and install the spark plugs again.

6.1.5 Daub anti-rust grease to the parts which are easy to rust like flywheel, clutch plate & etc.

6.1.6 Loosen the fan belt.

6.1.7 Drain out all gasoline and clean fuel tank.

6.1.8. Pack the engine with water proof material. Put some drier inside the bag.

6.1.9 Put the engine in a room with good ventilation and keep away with corrosive goods.

6.1.10 Check the engine every 2 months for corrosion. Take measures to avoid corrosion.


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6.2 Start Engine after Long Storage

6.2.1 Clear away the grease.

6.2.2 Refill coolant.

6.2.3 Refill oil.

6.2.4 Refill gasoline.

6.2.5 Check the battery liquid.

6.2.6 Connect the battery with engine. Apply Vaseline to the contacts.

6.2.7 Check and fasten all connections.

6.2.8 Follow the previous procedures to start the engine.

4y operation manual mdn-18s

Documents

maintenance of gasoline

engine configuration

check engine

engine inspection

usage of gasoline engine

maintenance cycle

lubricating system

contents chapter