Engine Operation, Repair, Maintenance and Trouble Shooting

Gasoline engine

Engine capable of compressing air-fuel mixture

in order to create explosion when ignited.

Diesel engine

Engine that raises the temperature of the air high

enough during compression to create combustion of

fuel.

d. All of the above

Which of the following is an advantage of compressionignition

over spark-ignition engine?

a. Higher reliability

b. Uniform distribution of fuel in each cylinder

c. Uniform torque characteristics

d. All of the above

e. None of the above

d. All of the above

Which of the following is an advantage of two-stroke over

4-stroke engine?

a. Power stroke is much higher for the same engine size and

speed.

b. Simple in construction.

c. Higher mechanical efficiency.

d. All of the above

e. None of the above

d. All of the above

Which of the following is a possible cause of engine's failure

to start up?

a. No gas

b. Damage spark plugs

c. Dirty/clogged air filter

d. All of the above

a. Gasoline engine

Engine capable of compressing air-fuel mixture

in order to create explosion when ignited.

a. Gasoline engine

b. Diesel engine

c. Flexi-Fuel Engine

d. None of the above

b. Diesel engine

Engine that raises the temperature of the air high

enough during compression to create combustion of

fuel.

a. Gasoline engine

b. Diesel engine

c. Flexi Fuel Engine

d. None of the above

c. All of the above

Which of the following is a possible cause of engine

running poorly or stalling after starting?

a. Governor needs adjustment.

b. Engine accessories are jammed.

c. All of the above

d. None of the above

c. All of the above

Excessive smoke while engine is running is due to

___.

a. oil has reached exhaust manifold

b. cracked cylinder head gasket

c. All of the above

d. None of the above

d. All of the above

What factor causes overheating of engines?

a. Blocked cooling fins

b. Dirty or clogged air intake

c. Faulty radiator and/or water pump

d. All of the above

e. None of the above

d. All of the above

What factor causes knocking noise of engines.

a. Carbon deposit inside the cylinder

b. Engine has overheated

c. Spark-plug damaged

d. All of the above

e. None of the above

e. All of the above

Which of the following problems frequently

experienced in diesel engines?

a. Engine overheating

b. Oil leakages

c. Oil supply problem

d. Using wrong fuel

e. All of the above

f. None of the above

d. All of the above

What is the negative effect of overheating of

engine.

a. Damage to bearings and crankshaft

b. Piston expanding and scraping against cylinder

walls

c. Cylinder head swelling, distorting , and braking

d. All of the above

Cylinder Head

Problems related to this are usually categorized by loss of COMPRESSION

cylinder head

Cracks in __ ___, which leads to leakages, are also a common issue as are internal

casting defects

Damaged Bearings

They face a lot of stress due to the daily friction experienced, such as

insufficient LUBRICATION and

improper selection of bearing material for the engine type at hand

Gasket

The most common failure in ____ is OVERHEATING via coolant leaks

diesel

In general,

___ engines are more prone to gasket failure than other types of engine largely because

___ gaskets regularly face higher combustion pressure.

e. All of the above

Engine part that frequently encounters problems.

a. Piston

b. Gasket

c. Cylinder head

d. Bearings

e. All of the above

f. Three of the above

d. All of the above

When diesel engine lacks power, the probable

cause is ___.

a. lack compression

b. choked air supply

c. heavy carbon deposit on the intake valve

d. All of the above

i. All of the above

Which of the following is a common cause of

troubles among multiple-cylinder diesel engines?

a. Abnormal exhaust

b. Hard to start

c. Lack of power

d. Overheating

e. Defective instruments

f. Air leakages

g. Fuel leakages

h. Malfunctioning of fuel injection equipment

i. All of the above

j. None of the above

black

When there is INSUFFICIENT AIR during combustion of fuel,

the color of the smoke coming out of the muffler is ___.

blue

When the LUBRICATING OIL is carried into the combustion

chamber of the engine, the color of smoke will be ___.

gray

When EXCESSIVE amount of WATER is mixed with the

fuel or there is leaky valve set rings, the color of the

smoke is ___.

e. All of the above

What is the factor that causes heavy knocking in

cylinders?

a. Too early or too late injection

b. Chocked or enlarge nozzle holes

c. Insufficient lubricating oil

d. Too hot circulating water

e. All of the above

f. Three of the above

e. All of the above

Which of these factors causes high-cooling wateroutlet

temperature?

a. Low water pressure

b. Water pump failure

c. Engine too hot

d. Malfunctioning of thermostat valve.

e. All of the above

f. Three of the above

e. All of the above

What factor causes the engine to run irregularly?

a. Damage governor

b. Water in fuel

c. Leaky fuel pump valve

d. Defective injection nozzle

e. All of the above

f. None of the above

d. All of the above

What factor affects the frequency of changing engine oil.

a. Type of engine (diesel or gasoline)

b. Age of engine

c. Operating condition of engine

d. All of the above

e. None of the above

b. black

When there is insufficient air during combustion of fuel,

the color of the smoke coming out of the muffler is ___.

a. blue

b. black

c. gray

d. All of the above

e. None of the above

b. blue

When the lubricating oil is carried into the combustion

chamber of the engine, the color of smoke will be ___.

a. black

b. blue

c. gray

d. All of the above

c. gray

When excessive amount of water is mixed with the

fuel or there is leaky valve set rings, the color of the

smoke is ___.

a. black

b. blue

c. gray

d. All of the above

Parts of Diesel Engine that Frequently Encounter Problems

Piston

a. Timing belt snapping.

b. Piston rings becomes worn out.

c. Piston slap (noisy piston).

d. Piston becoming burnt (usually dirty fuel injectors).

e. Piston becoming cracked (caused by frequent use of

poor quality fuel.

Piston slap

noisy piston

dirty fuel injectors

Piston becoming burnt is caused by

frequent use of

poor quality fuel.

Piston becoming cracked (caused by

100 to 250 hours

Frequency of changing engine oil for MODERN DIESEL

farm tractors

75 to 150 hours

Frequency of changing engine oil for OLDER DIESEL

farm tractors

50 to 100 hours

Frequency of changing engine oil for gasoline powered

farm tractors.

At least once a year

Frequency of changing engine oil for light-used tractors.

Every 6 months

Frequency of changing engine oil for single-piston

gasoline engine used by farmers.

50 hours

Required oil change for initial breaking-in of engine to

remove initial contaminants from manufacturing process

50 to 100 hours

Frequency of engine oil change in regular operation

of single-piston gasoline engine.

50 hours

Engine subjected to harsh condition like dusty, hot

climatic condition will required changing oil every ___

of operation.

100 to 200 hours

For routine use, single-piston diesel engines require

changing of oil every ___.

50 to 100 hours

For heavy-duty use, single-piston diesel engines

require changing of oil every ___.

g. All of the above

Which of the enumerated factors affects oil-change

frequency in diesel engine?

a. Type of use

b. Oil type

c. Manufacturer's recommendations

d. Operating conditions

e. Oil analysis

f. Engine age and condition

g. All of the above

h. Four of the above

Every 500 hours of use

Frequency of changing air filter in tractors

more frequent

Dusty or dirty environment may require ___ change of

filter.

Once a season

Frequency of changing spark-plugs in small engines

e. All of the above

Which of the following factors affects frequency of air

filter replacement?

a. Operating environment

b. Usage intensity

c. Signs of clogged filter

d. Manufacturer recommendation

e. All of the above

f. None of the above

e. All of the above

Which among the enumerated factors affects sparkplug

life in single-piston engines?

a. Type of spark plug

b. Operating condition

c. Engine type

d. Signs of wear

e. All of the above

f. None of the above

a. them in one set

When changing spark plug for multiple-cylinder

engine, it is recommended to change ___.

a. them in one set

b. only those who are damaged

c. one at a time

d. None of the above

a. Every 500 hours of use

Frequency of changing air filter in tractors.

a. Every 500 hours of use

b. Every 750 hours of use

c. Every 1000 hours of use

d. None of the above

a. more frequent

Dusty or dirty environment may require ___ change of

filter.

a. more frequent

b. less frequent

c. seldom frequent

d. None of the above

a. Once a season

Frequency of changing spark-plugs in small engines.

a. Once a season

b. Twice a season

c. Thrice a season

d. None of the above

a. 100 to 200 hours

For routine use, single-piston diesel engines require

changing of oil every ___.

a. 100 to 200 hours

b. 200 to 300 hours

c. 300 to 400 hours

d. Ne of the above

a. 50 to 100 hours

For heavy-duty use, single-piston diesel engines

require changing of oil every ___.

a. 50 to 100 hours

b. 100 to 150 hours

c. 150 to 200 hours

d. None of the above

a. 50 to 100 hours

Frequency of engine oil change in regular operation

of single-piston gasoline engine.

a. 50 to 100 hours

b. 100 to 150 hours

c. 150 to 200 hours

d. None of the above

b. 50 hours

Engine subjected to harsh condition like dusty, hot

climatic condition will required changing oil every ___

of operation.

a. 25 hours

b. 50 hours

c. 75 hours

d. None of the above

b. 100 to 250 hours

Frequency of changing engine oil for modern diesel farm tractors.

a. 50 to 100 hours

b. 100 to 250 hours

c. 250 to 300 hours

d. None of the above

a. 75 to 150 hours

Frequency of changing engine oil for older diesel

farm tractors.

a. 75 to 150 hours

b. 150 to 250 hours

c. 250 to 300 hours

d. None of the above

c. At least once a year

Frequency of changing engine oil for light-used tractors.

a. 50 to 200 hours

b. 200 to 350 hours

c. At least once a year

d. None of the above

b. Every 6 months

Frequency of changing engine oil for single-piston

gasoline engine used by farmers.

a. Every months

b. Every 6 months

c. Every 12 months

d. None of the above

a. 50 to 100 hours

Frequency of changing engine oil for gasoline powered

farm tractors.

a. 50 to 100 hours

b. 100 to 150 hours

c. 150 to 200 hours

d. None of the above

a. 50 hours

Required oil change for initial breaking-in of engine to

remove initial contaminants from manufacturing process.

a. 50 hours

b. 100 hours

c. 150 hours

d. None of the above

1. valves must sit properly on the valve seat;

2. good fit must exist between piston rings and cylinder wall;

3. use of recommended oil to enable it to seal minute gaps between the piston rings and

cylinder wall;

4. cylinder head gasket must be tightly secured.

The cylinder should have good compression. To ensure good compression

correct air-fuel mixture

In general, there are

two carburetor adjustments, the high speed and the low speed adjustments, neither of which

should affect the other.

Carburetor adjustments should always be made on hot engine and

operating and generally, the low speed is made first.

knocking

The combustible mixture must be

ignited at the right moment so that its maximum effect would be felt when the piston is at

TDC.

If the maximum effect of ignition occurs before TDC, there will be ___ and

appreciable loss of power.

power loss.

The piston needs to reach TDC but the expanding gases is

resisting it. If the maximum expansion occurs after TDC, the maximum effect will not be felt

resulting in considerable __ ___

spark advance

If the engine is at low speed, the spark may occur at TDC. However, as engine

speed increases, the spark must occur before TDC so that maximum expansion will be felt at

TDC. The higher the speed, the earlier the spark should occur before TDC

Servicing

a term which includes both the essential daily and periodic maintenance

work.

Daily maintenance

involves the simple activities such as checking the levels of fuel and oil,

condition of the cooling system and transmission belt, and the tightness of the bolts, nuts and

screws.

Periodic maintenance

involves the scheduled cleaning, replacement or

adjustment of parts related to the valve, ignition, fuel, lubrication and cooling systems

25 hrs

The fins, shrouds and fan screen must be cleaned at least every __

hours of operation.

warm.

Service the air cleaner when the oil is changed.

Drain the oil when the engine is

___.

After the oil is well drained, fill with the correct quantity and weight of oil.

above

The engine

manufacturer will usually recommend

SAE 30,

SAE 40,

SAE 10W-30

or SAE 10W-40

for ambient

temperature ___ 40°F.

below

Recommendations for temperature ___ 40°F do not apply to us.

5

Check the oil level every ___ hours of

continuous operation

cooling and

lubrication systems

The servicing of the valve, fuel and ignition systems are not as simple as the ____.

These are usually referred to mechanics who have the necessary skill and

tools to perform the job

(1) Compression;

(2) Ignition (spark at the plug);

(3) Carburetion (fuel and air

into the cylinder)

[Troubleshooting small gasoline engines]

1.

When trouble shooting a small engine, first check the three things any engine must have

to start and run:

[Troubleshooting small gasoline engines]

2.

Check the compression by cranking the engine to the point of strongest resistance, and

note whether the engine snaps back. If there seems to be no resistance, check to see if the

spark plug is tight and its gasket is in place. There are other reasons for lack of compression

but the checking of these are beyond the capability of the ordinary user.

[Troubleshooting small gasoline engines]

3.

Check the ignition by removing the cable from the spark plug, holding the cable about

3/16 inch away from some metal surface on the engine and cranking the engine. If a bluish

spark will jump a 3/16-inch gap, the trouble is not in the ignition but may be in the spark plug.

[Troubleshooting small gasoline engines]

4.

Remove the spark plug and reconnect it with the cable. Place the threaded portion of

the plug in contact with some metal surface of the engine and crank the engine. If a bluish

spark is produced at the spark plug gap, the trouble is not in the spark plug.

[Troubleshooting small gasoline engines]

5.

Check the carburetion by holding a thumb over the spark plug hole while cranking the

engine a few turns. Your thumb should be moist with gas if fuel is reaching the cylinder. If

there is no gas getting to the cylinder, check the vent in the gas tank cap, check for fuel in the

tank and check the fuel lines to see that the fuel is getting to the carburetor.

(1) Compression;

(2) Fuel injection

[Troubleshooting small diesel engines]

1.

When trouble shooting a small diesel engine, first check the two things a diesel engine

must have to start and run:

[Troubleshooting small diesel engines]

2.

Check the compression by following the procedure for checking compression of small

gasoline engines.

[Troubleshooting small diesel engines]

3.

Check the flow of fuel by opening the bleeder located at the low pressure side of the

fuel injector. If no fuel flows out of the bleeder, the fuel filter is probably clogged assuming that

there is fuel in the tank and the fuel shut-off valve (fuel cock) is turned on.

[Troubleshooting small diesel engines]

4.

If air and fuel flow

out of the bleeder, continue bleeding the system. This occurs when the engine runs out of fuel

during operation.

[Troubleshooting small diesel engines]

5.

Tighten the bleeder and the engine should now start. If the engine still does

not start, there is probably something wrong with the injector nozzle. However, a competent

mechanic is required to perform the repair.

5000 to 10000 km

regular oil change for every ___ km

periodic tuning

adjust valve clearance, ignition timing and fuel injection system

freeze

weak coolant can ___, causing damage to the engine block and radiator

coolant hydrometer

a device that check the coolant strength

basic principle to check small engine problems

1. check the easiest things first

2. verify the fundamental operating requirements

5 Fundamental Operating Requirements

1. Proper carburetion

2. Correct ignition system operation

3. Adequate lubrication

4. Sufficient cooling

5. Proper compression

30-45 psi

minimum pressure compression for starting

[______ psi]

90 psi

minimum pressure compression for efficient operation and sufficient power

[___ psi]

Tachometer

it is a digital or optical device used to measure the rpm of engine

Differential pressure tester

a device that requires the application of air pressure to the cylinder being tested with the piston at TDC on the compression stroke

Black smoke

rich fuel mixture, clogged air filter, faulty injector

REPAIR: clean air filter, service injector, adjust fuel system