Interview Techniques for Hiring Heavy-Duty Mechanics

Why Hiring the Right Mechanic Matters More Than Ever

The technician shortage in heavy-duty repair isn't news — it's been building for years. But the pressure is real: demand for skilled diesel mechanics is outpacing supply, and the competition for good candidates is fierce.

For independent and mid-sized shop owners, this means every hire counts. A bad hire costs time, money, and morale. A great hire can transform your shop's productivity and reputation.

The difference often comes down to how you run your interviews.

This guide will help you identify the right candidates, ask the right questions, and make hiring decisions you won't regret.

Before the Interview: Know What You're Looking For

Before you sit down with a candidate, get clear on what you actually need.

Define the Role

• What systems will they work on? (Engines, transmissions, electrical, HVAC, etc.)
• What certifications are required or preferred? (ASE, OEM-specific, CDL?)
• Will they be in the shop, on the road, or both?
• What level of experience do you need — entry, mid, or senior?

Identify Your Non-Negotiables

Some things can be taught. Others can't. Be honest about what you're willing to train for — and what's a dealbreaker.

Examples:

• Non-negotiable: Shows up on time, works safely, communicates clearly
• Trainable: Specific software systems, shop-specific procedures

Consider Culture Fit

Skills matter, but so does attitude. A technically brilliant tech who clashes with your team or ignores processes will hurt more than help.

Screening Before the Interview

Don't waste time interviewing candidates who aren't qualified. A quick phone screen can filter out mismatches early.

Ask:

• What types of trucks/equipment have you worked on?
• What certifications do you hold?
• What's your experience with diagnostics and modern systems?
• Why are you looking to leave your current role?
• What's your availability and salary expectation?

If the answers don't align with the role, move on. If they do, bring them in.

The Interview: What to Ask (and Why)

A good interview balances technical assessment with behavioral insight. You want to know:Can they do the job? andWill they do it well, here?

Technical Questions

These should be tailored to your shop's work. Here are some examples:

Diesel Engine Systems:

• "Walk me through how you'd diagnose a no-start condition on a Cummins ISX."
• "What's your process for troubleshooting a low-power complaint?"

Electrical/Diagnostics:

• "How comfortable are you with scan tools and OEM software?"
• "Tell me about a time you tracked down an intermittent electrical issue."

Preventive Maintenance:

• "What does a thorough PM inspection look like to you?"
• "How do you prioritize repairs when multiple issues are found?"

Tip: Listen for process and reasoning, not just right answers. A good tech explains their thinking.

Behavioral Questions

Past behavior predicts future behavior. Use "Tell me about a time when…" questions to understand how they handle real situations.

• "Tell me about a time you made a mistake on a repair. What happened, and what did you do?"
• "Describe a situation where you had to work under pressure to meet a deadline."
• "How do you handle a disagreement with a coworker or supervisor?"
• "Tell me about a time you had to learn a new system or tool quickly."

Look for honesty, accountability, and adaptability. Avoid candidates who blame others or can't give specific examples.

Culture and Fit Questions

• "What kind of shop environment do you do your best work in?"
• "What's most important to you in a job?"
• "How do you stay current with new technology and techniques?"
• "What would your last supervisor say about your work?"

These questions reveal whether the candidate will thrive inyour shop — not just any shop.

Hands-On Assessment

If possible, bring promising candidates in for a practical evaluation. This could be:

• A paid working interview (a few hours on a real or simulated job)
• A diagnostic scenario (present a problem and ask them to walk through their approach)
• A shop tour where they can ask questions and interact with your team

Seeing someone work tells you more than any interview question.

Red Flags to Watch For

Trust your instincts — and watch for warning signs:

• Vague answers: Can't give specifics about past work or accomplishments
• Blame-shifting: Every problem was someone else's fault
• Job-hopping without explanation: Frequent moves with no clear reason
• Overconfidence: Claims to know everything, dismisses questions
• Lack of curiosity: Doesn't ask questions about the shop, team, or work

A great candidate is curious, honest, and self-aware.

After the Interview: Making the Decision

Check References: Always. Ask previous employers about reliability, skill level, and how they handled challenges.

Discuss as a Team: If the candidate met other staff, get their input. They'll be working together every day.

Move Quickly: Good candidates don't stay on the market long. If you've found the right person, make the offer.

Onboarding: Set Them Up to Succeed

Hiring is just the first step. A strong onboarding process helps new techs hit the ground running:

• Introduce them to the team and shop culture
• Walk through your systems, software, and SOPs
• Pair them with a mentor for the first few weeks
• Check in regularly to address questions and concerns

The first 90 days shape whether a hire sticks — or starts looking elsewhere.

Final Thoughts: Hire Slow, Fire Fast

Finding great technicians is hard. But rushing the process — or settling for "good enough" — will cost you more in the long run.

Take the time to define what you need, ask the right questions, and evaluate candidates thoroughly. When you find the right person, invest in their success.

That's how you build a team that drives your shop forward.

Looking for tools to help manage your growing team?Book a demo of ShopView and see how we help shops streamline operations, track productivity, and support technician success.