Mechanical Maintenance Engineer Interview Questions UK: 8 Real Questions and What Interviewers Want

Most Mechanical Maintenance Engineer interviews in the UK follow a pattern, and knowing it beats guessing. Below are eight questions from our bank of 16, each with a note on what the interviewer is really after.

Eight Mechanical Maintenance Engineer interview questions, and what the interviewer is thinking

1. How would you diagnose a bearing failure on a gearbox, and what would you do to stop it happening again?

Why they ask: Bearing failure is one of the most common mechanical faults and tests both diagnosis and root cause thinking.

2. What are the main methods of shaft alignment, and why does misalignment matter?

Why they ask: To test practical precision skills on rotating equipment.

3. Explain what LOLER and PUWER require of you when you are using or maintaining lifting equipment.

Why they ask: Mechanical engineers regularly work with hoists and slings, so legal awareness of lifting regulations is essential.

4. What is the difference between a centrifugal pump and a positive displacement pump, and how would you troubleshoot low flow from a centrifugal pump?

Why they ask: Pumps are central to most plants, so this tests core mechanical knowledge.

5. How do you use a CMMS and maintenance data to improve how a plant is maintained?

Why they ask: To see whether you work with data rather than just spanners.

6. A critical pump fails during a night shift and the production supervisor asks you to get it running immediately. The pump is still hot and under pressure. What do you do?

Why they ask: To test safety discipline under production pressure.

7. Tell me about a time you led a repair or breakdown that was complex or had a high production impact.

Why they ask: To assess leadership and technical ability under real pressure.

8. What does a typical week look like for a mechanical maintenance engineer, and what attracts you to the role?

Why they ask: To check realistic understanding of the role and motivation.

A sample answer to question 1

How would you diagnose a bearing failure on a gearbox, and what would you do to stop it happening again?

I would start with the evidence before it is disturbed: vibration and temperature history, lubricant condition, noise reports and the failed bearing itself. Looking at the damage tells me a lot. Spalling on the race suggests fatigue or overload, discolouration means overheating, fluting points to electrical discharge, and corrosion pitting suggests water ingress. I would check shaft and housing fits with micrometers and bore gauges, alignment, and whether the seals were intact. Then I would look for causes upstream: wrong grease or over-greasing, misalignment, soft foot, imbalance or incorrect installation method such as hammering the race. After replacement I would use an induction heater or hydraulic method, set the preload or clearance to the manufacturer's data, and align with a laser tool. To prevent a repeat, I would fix the root cause, adjust the lubrication schedule, and add vibration monitoring so we catch early signs, recording the findings in the CMMS.

Common mistake to avoid: Just replacing the bearing; ignoring lubrication and alignment

Want the rest?

Full model answers, key points and common mistakes for all 16 questions are on the Mechanical Maintenance Engineer interview questions page. The first five are free, no sign-up needed.