(SEM VII) THEORY EXAMINATION 2023-24 TROUBLE SHOOTING, SERVICE & MAINTENANCE REPAIR

SECTION A – Very Short Answer Type

(2 × 10 = 20 Marks)

a) Situations where Condition Monitoring is more suitable

Condition monitoring is suitable for critical, costly, and continuously operating machines, where unexpected failure can cause heavy loss, such as engines, gearboxes, and industrial machines.

b) Trip sheets

Trip sheets are records maintained for vehicles showing distance traveled, fuel consumed, route taken, and time, used to monitor vehicle performance and efficiency.

c) Types of maintenance cost

Preventive maintenance cost

Breakdown maintenance cost

Corrective maintenance cost

d) Lubrication oil topping up

Lubrication oil topping up means adding oil to the engine to maintain the required oil level between scheduled oil changes.

e) FIP adjustment and testing

Fuel Injection Pump (FIP) adjustment ensures correct fuel quantity and timing, while testing checks pump performance using calibration equipment.

f) Emergency maintenance vs general maintenance

Emergency maintenance is unplanned and immediate, done after sudden failure, whereas general maintenance is planned and preventive.

g) Wiring harness testing

Wiring harness testing checks continuity, insulation, and proper connections to ensure reliable electrical power flow in the vehicle.

h) Voltage of a fully charged battery cell

Each fully charged lead-acid battery cell contributes approximately 2.1 volts.

i) Fuel feed system

The fuel feed system supplies fuel from the tank to the engine at the required pressure and quantity.

j) Window glass actuation

Window glass actuation is the mechanism that raises or lowers window glass, either manually or electrically.

SECTION B – Long Answer Type

(Attempt any three – 10 Marks each)

2(a) “Engine tuning is a life-extending activity” – Justification

Engine tuning involves adjusting ignition timing, fuel supply, valve clearance, and idle speed to ensure optimal performance.

Justification:

Reduces engine wear

Improves fuel efficiency

Prevents knocking and overheating

Enhances power output

Example:
Correct ignition timing prevents detonation, protecting pistons and valves, thus extending engine life.

2(b) Short notes

(a) Overcharging of battery

Overcharging occurs when excessive voltage is supplied, causing:

Water loss

Plate damage

Overheating

It reduces battery life.

(b) Ignition timing light

An ignition timing light is used to check and adjust ignition timing by flashing light synchronized with spark plug firing.

2(c) Method of setting ignition timing using timing light

Steps:

Connect timing light to battery and spark plug wire

Start engine and aim light at timing marks

Observe mark alignment

Adjust distributor until correct timing is achieved

This ensures smooth engine operation.

2(d) Capacitor Discharge Ignition (CDI) testing method

CDI stores electrical energy in a capacitor and releases it quickly to the ignition coil.

Testing procedure:

Check capacitor voltage

Inspect ignition coil resistance

Test triggering circuit

Verify spark strength

CDI ensures strong spark at high speeds.

2(e) Minor body panel beating, tinkering, and shouldering

Panel beating: Straightening dented panels

Tinkering: Minor body repairs using tools

Shouldering: Smoothing repaired surfaces before painting

These restore vehicle appearance.

SECTION C – Descriptive Answer Type

3(a) Servicing and its types

Servicing is the routine inspection, adjustment, and replacement of vehicle parts to maintain performance.

Types:                                                                Free servicing

Paid servicing                                                    Preventive servicing

Periodic servicing

Servicing prevents breakdowns and improves safety.

3(b) Types of service stations

Authorized service station                                 Independent service station

Specialized service station                                 Mobile service station

Each type differs in equipment, expertise, and service scope.

4(a) Reconditioning and repairing of engine components

Reconditioning:

Restoring worn components using:                    Grinding

Honing                                                                Reboring

Repairing:                                                            Replacing or fixing damaged parts like:

Pistons                                                                 Valves

Bearings                                                              These processes reduce replacement cost.

4(b) Cleaning and inspection

Cleaning:                                                             Removal of dirt, grease, and deposits.

Techniques:                                                          Solvent cleaning

Steam cleaning                                                    Ultrasonic cleaning

Inspection:

Visual, dimensional, and non-destructive testing to detect wear and cracks.

5(a) Objectives of transmission and related troubles

Objectives:                                                           Transmit power

Vary speed and torque                                        Allow reverse motion

Troubles:                                                              Gear slipping

Noise                                                                   Hard shifting

Maintenance:                                                       Lubrication

Proper adjustment                                               Periodic inspection

5(b) Tire rotation

Need:                                                                  Uniform tire wear

Longer tire life                                                    Better handling

Arrangements:                                                    Front-to-rear

Cross rotation                                                     Five-tire rotation

(Tire rotation diagrams are usually drawn in exams.)

6(a) Need for regular electrical maintenance

Electrical maintenance ensures:                           Reliable starting

Proper lighting                                                     Efficient charging

Battery troubles:                                                   Sulphation

Low electrolyte level                                             Overcharging

Loose terminals

6(b) Ignition system and comparison

Ignition system:

Produces spark to ignite air-fuel mixture.

7(a) Corrosion and anti-corrosion methods

Corrosion:                                                     Gradual deterioration of metal due to chemical reaction.

Types:                                                            Uniform corrosion

Galvanic corrosion                                        Pitting corrosion

Prevention:                                                    Painting

Galvanization                                                Cathodic protection

Use of coatings

7(b) Regular body maintenance & window winding mechanism

Body maintenance steps:                              Washing and waxing

Rust inspection                                              Paint touch-ups

Lubrication of hinges                                     Window winding mechanism:

Consists of:                                                     Handle or motor

Regulator mechanism                                    Glass channel

It converts rotational motion into vertical movement of glass.