For most RRB ALP aspirants, Diesel Mechanics is not just a subject — it is the qualification gate.
Every year, thousands of candidates score well in Maths, Reasoning, and Science, yet fail to qualify because of Part-B (Diesel Trade). The reason is simple:
Diesel Mechanics is trade-specific, concept-based, and strictly qualifying.
This creates a common aspirant intent:
How many Diesel Mechanics questions are asked in RRB ALP?
Which topics dominate CBT-2?
What is the safest preparation strategy to clear Part-B?
This blog answers all these questions in depth, with:
Expected question count
Topic-wise weightage
Smart preparation strategy
30-day actionable plan
Common mistakes & expert tips
Before planning any strategy, you must understand where Diesel Mechanics fits in the exam.
| Section | Subjects | No. of Questions | Marks | Time |
|---|---|---|---|---|
| Part A | Maths + Reasoning + General Science | 100 | 100 | 90 Minutes |
| Part B | Relevant Trade (Diesel Mechanic) | 75 | 75 | 60 Minutes |
✔ Important Rule:
Part-B is qualifying in nature, but failing it means total disqualification, regardless of Part-A score.
| Parameter | Details |
|---|---|
| Total Questions | 75 |
| Question Type | Objective (MCQ) |
| Level | ITI Diesel Mechanic (Easy–Moderate) |
| Negative Marking | 1/3 mark |
| Qualifying Requirement | Mandatory |
✔ Every Diesel candidate must attempt all 75 questions from Diesel Mechanics only.
The Diesel Mechanics syllabus is largely based on ITI Diesel Mechanic trade, with emphasis on practical knowledge and engine systems.
Diesel Engine Basics
IC Engine Cycles
Fuel Injection System
Air Intake & Exhaust System
Cooling System
Lubrication System
Turbocharging & Supercharging
Engine Components
Heat Engine & Thermodynamics
Maintenance & Troubleshooting
Based on previous RRB ALP CBT-2 papers, trade syllabus, and trend analysis, the approximate distribution is:
| Topic | Expected Questions (Out of 75) |
|---|---|
| Diesel Engine Basics & Classification | 6–8 |
| Two-Stroke & Four-Stroke Cycle | 6–7 |
| Fuel Injection System | 10–12 |
| Air Intake & Exhaust System | 4–5 |
| Cooling System | 5–6 |
| Lubrication System | 5–6 |
| Turbocharger & Supercharger | 3–4 |
| Engine Components & Valve Mechanism | 8–10 |
| Heat Engine & Thermodynamics | 6–8 |
| Maintenance, Defects & Troubleshooting | 8–10 |
✔ Fuel System + Engine Parts = Nearly 30–35% of the paper
Some topics consistently appear and are easy scoring if concepts are clear.
Fuel Injection Pump (Inline, Rotary)
Injector Types & Spray Pattern
Common Rail Direct Injection (CRDI)
Valve Timing Diagram
Cooling vs Lubrication Comparison
Engine Knocking Causes
Turbocharger Working Principle
Black, Blue & White Smoke Reasons
Overheating & Low Power Faults
✔ These questions are direct, factual, and diagram-based.
Understand working principles
Focus on flow paths and diagrams
Avoid mugging up definitions only
Minimum 40–60 MCQs per topic
Maintain an error notebook
Revise weak areas every 7 days
Reattempt wrong MCQs
| Days | Topics |
|---|---|
| Day 1–5 | Diesel Engine Basics + IC Cycles |
| Day 6–10 | Fuel Injection System |
| Day 11–14 | Cooling & Lubrication |
| Day 15–18 | Air System + Turbocharging |
| Day 19–22 | Engine Components |
| Day 23–25 | Heat Engine & Thermodynamics |
| Day 26–30 | Full Revision + MCQ Tests |
| Accuracy Level | Safe Attempts |
|---|---|
| 90%+ | 70–72 |
| 80–85% | 65–68 |
| Below 75% | Risky Zone |
✔ Target Score: 55–60 marks out of 75
❌ Treating Part-B lightly
❌ Skipping troubleshooting questions
❌ Ignoring diagrams
❌ Not revising fuel injection concepts
❌ Depending only on theory books
✔ Remember: Part-B failure = total elimination
Yes. For Diesel trade candidates, Part-B with 75 questions is compulsory and qualifying.
Yes. ITI syllabus + previous year MCQs is sufficient.
Very few. Mostly efficiency, compression ratio, and basic power concepts.
Easy to Moderate, concept-based rather than tricky.
Diesel Mechanics is not difficult — it is underestimated.
✔ 75 questions decide your qualification
✔ Concept clarity > rote learning
✔ Fuel system & engine parts are scoring gold
✔ Regular MCQ practice ensures success
✔ If you prepare Diesel Mechanics seriously, RRB ALP selection becomes realistic.
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