Serpentine Belt Squeal Belt & Tensioner Replacement

By the Radman Auto Repair team, independent auto repair in Etobicoke since 1999 · Updated November 2026

The serpentine belt drives the alternator, A/C compressor, power steering and often the water pump. A worn belt, weak tensioner or noisy pulley causes squeals and chirps, especially on cold or wet mornings. A broken belt can leave you stranded and overheating.

Symptoms

What Causes It

Before You Start

• Park on level ground, set the parking brake and chock the wheels. Never work under a car held up only by a jack: use rated jack stands.
• Let the engine and exhaust cool before you touch them; coolant systems are under pressure when hot.
• Wear safety glasses and gloves, and disconnect the 12V battery before unplugging electrical parts or working near airbags.
• Check for open recalls on your VIN (Transport Canada or the manufacturer’s site) before you buy parts: a recall repair is free at the dealer.
• Keep hands clear of the belt with the engine running; never reach in while it turns.

Step-by-Step: Serpentine Belt Squeal

1. Photograph the routing. Photograph the routing or find the diagram.
2. Inspect the belt. With the engine off, look at the ribbed side for cracks, missing chunks and a shiny, glazed surface. Modern belts can also wear without cracking, so a belt wear gauge helps.
3. Watch the tensioner. With the engine running, watch the tensioner arm. A little movement is normal; a large shake or wobble means the tensioner is weak.
4. Spray test. A quick water spray changes the noise if the belt is the source.
5. Release the tension. Rotate the tensioner and slip the belt off.
6. Spin the pulleys. With the belt off, spin each idler and the tensioner pulley by hand. They should turn smoothly and quietly with no play or roughness.
7. Install new parts. Fit any new tensioner or pulley, then route the new belt following your photo or diagram and release the tensioner slowly onto it.
8. Test. Start the engine and check the belt tracks correctly.

When to Stop and Bring It In

• The noise comes from an accessory such as the alternator or A/C compressor.
• The belt keeps coming off.
• There is oil or coolant on the belt.
• The timing belt is due as well. See timing belt vs serpentine belt.

Not sure, or out of time? Radman Auto Repair in Etobicoke does this repair every week. Book online or call (416) 742-4521.

Also Known As

People search for “serpentine belt squeal”, “belt squeal on startup”, “squealing noise when A/C on”, “tensioner noise” or “drive belt replacement”. The part is the serpentine (drive) belt and tensioner.

Frequently Asked Questions

See also Timing Belt vs Serpentine Belt, Multi-Point Inspection, Failing Alternator, DIY Repair Guides by Manufacturer.

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11:02 10 Oct 26

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20:58 31 Aug 26

I cannot say enough good things about Livio and the team at Radman Auto Repair in Rexdale. We brought in my son’s 2015 Mitsubishi Lancer because the A/C was malfunctioning. We had already been to two other shops, paid for diagnostics, and received different explanations, so we were frustrated and unsure what to do next. Livio was outstanding. He listened carefully, looked at the issue, and explained everything clearly and in detail in a way that actually made sense. He was able to narrow down what was going on within minutes, without guessing, pressure, or recommending unnecessary work. What really stood out was that he did not charge us another diagnostic fee after learning we had already paid for two separate diagnoses. Even better, the work was completed the same day, which was a huge relief. It is rare to find a mechanic who is knowledgeable, honest, patient, efficient, and genuinely focused on helping customers understand the real issue before they spend money on repairs. Livio truly gets it. We are so happy we found Radman Auto Repair and would highly recommend Livio and his team to anyone looking for trustworthy, skilled, and customer-focused service..

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04:42 10 Aug 26

My 2015 Honda CR-V was blowing hot air and making noise when the A/C was on. The Compressor and Expansion valve needed replacement due to metal debris in the system. I rarely write reviews, but I felt it would be wrong not to appreciate Radman for their service, especially after what I went through before finding them. I’m writing this one month after the repair because I wanted to test my A/C on multiple long trips before recommending them. One thing I learned from this experience is that many mechanics know how to replace parts, but very *few follow the right procedures* and perform the proper checks. I initially went for a cheaper repair at a local mechanic. The problem came back, and afterward he didn’t seem to know what to do next. I found Radman through Google reviews without any personal recommendation, so I was taking a chance. They properly diagnosed the issue, explained everything clearly before starting the work, didn’t exaggerate the problem, and charged me a reasonable price. A/C issues can be complicated but they answered all my questions and I honestly haven’t had such a good and detailed conversation with a mechanic in the GTA about an A/C problem. Their knowledge and experience with A/C systems really stood out. I also had a catalytic converter issue. Another mechanic simply recommended replacing it, which would have cost at least $2,000. Radman explained that considering the age and condition of my 2015 CR-V, such an expensive replacement might not make sense. They gave me the replacement cost but also suggested trying Cataclean first. I tried it, and so far I haven’t had any issues. After a month and several long trips, my A/C is still working well. It’s rare to find this combination of knowledge, transparency, and honesty. Thank you, Radman, for the knowledgeable and honest service. I genuinely appreciate it.

Moklas Salkon

17:17 23 Jun 26

I fix my cars myself but I always go to Radman for AC work. Been coming here for years and they do great work and are fairly priced. The guys are honest and reliable. Very clean waiting room too!

Alexa De Los Santos

18:30 26 May 26

Finding a mechanic who actually understands EVs and is completely trustworthy is hard to come by, but ⁠Radman Repair is excellent. The service was top-notch, they explained everything to me with so much patience, and the overall experience was a 10/10. 100% recommended!

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