Commercial Engine Builder

Mayfair Gearbox; Johannesburg; On-site; ZAR 180,000 - 280,000; Full time

Job summary

Mayfair Gearbox in Johannesburg seeks a Commercial Engine Builder to strip, diagnose, rebuild and assemble heavy‑duty diesel engines for trucks and commercial vehicles. You will work to OEM specifications and Mayfair standards, delivering high‑quality rebuilds with attention to tolerances and safety.

Responsibilities include fault finding, engine assembly, cylinder head work, testing and quality control, and coordinating with foreman for parts and timelines.

Qualifications

• Diesel engine rebuilding knowledge and procedures.
• 3–5 years experience in engine rebuilding (commercial diesel engines).
• Matric/Grade 12 required; Diesel Mechanic Trade Test advantageous.

Responsibilities

• Strip and dismantle diesel engines and parts.
• Diagnose engine failures and determine root causes.
• Rebuild engines to OEM specifications and Mayfair quality standards.
• Assemble engines with correct torque settings and tolerances.
• Replace worn components and ensure proper clearances and timing.
• Assist in cylinder head work and head gasket prep.
• Perform final testing and quality inspections.

Skills

Fault finding

Attention to detail

Independence

Teamwork

Education

Matric / Grade 12

Diesel Mechanic Trade Test

Tools

Torque wrenches

Dial gauges

Micrometers

Measuring tools

Job description

The Commercial Engine Builder will be responsible for stripping, diagnosing, rebuilding, and assembling heavy-duty diesel engines for trucks and commercial vehicles. The role requires strong mechanical expertise, attention to detail, and the ability to deliver high-quality rebuilds that meet Mayfair Gearbox standards, ensuring reliability and minimal comebacks.

Key Responsibilities

• Engine Stripping & Fault Finding
• Strip and dismantle commercial diesel engines safely and accurately.
• Diagnose engine failures and identify root causes (e.g., overheating, oil starvation, wear, incorrect fueling).
• Inspect components including crankshaft, pistons, liners, cylinder head, valves, camshaft, injectors, turbo systems, and oil pumps.
• Assess damage and provide accurate feedback for quoting and parts requirements.

Engine Rebuilding & Assembly

• Rebuild heavy-duty diesel engines to OEM specifications and Mayfair Gearbox quality standards.
• Assemble engines using correct torque settings and tolerances.
• Replace worn components such as bearings, gaskets, seals, liners, pistons, rings, valves, timing components, and pumps.
• Ensure correct setting of clearances, timing, and alignment.

Cylinder Head and Component Work

• Assist in cylinder head removal, inspection, and refitment.
• Perform valve lapping, injector sleeve inspections, and head gasket preparation.
• Ensure correct inspection of block and head surfaces.

Testing & Quality Control

• Perform final checks before engine completion.
• Conduct quality inspections to ensure correct assembly, cleanliness, and workmanship.
• Ensure all rebuilt engines are tested (where applicable) and meet performance standards.
• Identify potential issues early to prevent comebacks.

Workshop Coordination

• Liaise with foreman/service advisor regarding parts requirements and additional repairs.
• Provide technical input on turnaround times and job progress.
• Support fitment teams with engine installations when required.

Tool, Equipment & Housekeeping

• Use engine building tools and equipment correctly (torque wrenches, dial gauges, micrometers, measuring tools).
• Maintain cleanliness and organisation of the work area.
• Ensure tools and special tools are handled responsibly and returned after use.

Health & Safety Compliance

• Adhere to Mayfair Gearbox health and safety procedures.
• Ensure correct use of PPE and safe handling of heavy components.
• Maintain a safe and clean workshop environment at all times.

Minimum Requirements

• Matric / Grade 12 (preferred).
• Diesel Mechanic Trade Test (advantage).
• Minimum 3–5 years experience as an engine builder (commercial diesel engines).
• Experience working on heavy-duty truck engines (essential).
• Valid driver’s license (advantage).

Technical Knowledge Required

• Diesel engine rebuilding processes and procedures.
• Engine component measurement and tolerances.
• Knowledge of lubrication and cooling systems.
• Turbocharger systems and engine breathing systems.
• Fuel systems knowledge (injectors, pumps, common rail – advantage).
• Ability to interpret workshop manuals and OEM specifications.

Key Skills & Competencies

• Strong fault finding and diagnostic skills.
• High attention to detail and quality workmanship.
• Ability to work independently and meet deadlines.
• Good time management and productivity focus.
• Ability to work under pressure in a fast-paced environment.
• Good communication and teamwork skills.Strong mechanical aptitude and problem-solving ability.

Personal Attributes

• Honest, reliable, and accountable.
• Quality-driven with a strong work ethic.
• Willing to work overtime when required.
• Professional and disciplined.
• Ability to take instruction and follow processes.