Guide · Mechanical

5 noises your truck should never make.

A truck speaks before it breaks. Here are five noises that signal a repair bill — ranked by urgency, with the cost of ignoring them.

The golden rule: a new noise is a message.

Almost every major repair bill we see started as a small noise someone decided to tolerate. On a heavy truck, the difference between “I had it checked that day” and “I finished my contract first” is often tens of thousands of dollars.

These are the five noises we take seriously, from the most urgent to those you can plan for.

Worried about a noise?

Describe it over the phone: when it happens, cold or hot, at idle or under load. Often, we can already tell you whether to keep driving or stop.

514-654-0882

Mechanical shop · Mon–Fri 8am–6pm · Sat 8am–12pm

A deep engine knock (bottom end)

What it sounds like: A deep “knock-knock” at idle or under load, following engine speed.

What it probably is: Worn connecting-rod or crankshaft bearings, bottom-end play, or a faulty injector causing knock. On a heavy diesel engine such as an ISX, DD15 or MX-13, a developing bottom-end knock is a countdown to failure.

STOP. Continuing to drive can turn a bearing repair into a full engine replacement — the difference between a few thousand dollars and $25,000+.

Turbo whistling or howling

What it sounds like: A high-pitched whistle that rises with RPM, loss of power and smoke.

What it probably is: Play in the turbo shaft, damaged blades, or an intake or intercooler leak. A howling turbo can draw in its own oil; a turbo that breaks apart sends debris into the engine.

Soon. A leaking boost pipe is minor. A turbo with play should be replaced before it contaminates the intake.

Metallic brake grinding

What it sounds like: Grinding, metal-on-metal rubbing or a continuous squeal when braking.

What it probably is: Linings worn down to metal, a damaged drum or disc, a misadjusted slack adjuster or a broken brake-shoe spring. On air brakes, a brake overheating on one side can also signal a worn chamber or adjuster.

Immediate — this concerns your safety and your PEP inspection. A heavy truck that brakes unevenly risks failing the SAAQ inspection and poses a real danger on Highway 40.

Clunking in the suspension or steering

What it sounds like: A sharp front-end “clunk” over bumps, in a turn or when steering.

What it probably is: Worn kingpins, sway bar, equalizer bushings, deflated suspension airbags or play in the drag link. Steering play that clunks can also be felt in the steering wheel.

Soon. It rarely immobilizes the truck, but it means a failed inspection and faster tire wear in the meantime.

Belt squeal on startup

What it sounds like: A high-pitched squeal on a cold start or when the air conditioning engages.

What it probably is: A glazed or stretched serpentine belt, a tired tensioner, or a binding alternator or compressor pulley. It may seem minor, but a belt failing on the road can mean no charging, cooling or power steering on some setups.

Schedule it. A belt and tensioner are routine work at our shop, rather than an $800 tow beside Highway 20.

Frequently asked questions

Truck noises: your questions

My truck knocks at idle but drives normally. Can I finish the week?

Do not assume it is safe to keep driving. A bottom-end knock can turn a repairable engine into a major failure within hours. Have it assessed the same day. Call 514-654-0882, describe the noise and ask our workshop about an inspection.

How much does a noise diagnosis cost?

We start by listening and visually inspecting the truck at our Pointe-aux-Trembles workshop. Cost depends on investigation time; we give an estimate before starting. A noise can often be located in about 30 minutes.

My truck has broken down on the road. Can you come out?

Our roadside service covers greater Montréal for breakdowns, brakes and mechanical assistance. See the roadside-service page or call us directly.

How can I check for these noises before buying a used truck?

Check a cold start, listen at idle and under load, brake at low speed with the windows open and check full steering lock while stopped. At our yard, ask to hear a cold start and inspect the truck before purchase.

We listen to your truck. Free over the phone.

Full shop in Pointe-aux-Trembles: diagnostics, engine, brakes and suspension. If the truck cannot move, our roadside service comes to you.

514-654-0882

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