Bang, clang, boom –– If you hear these sounds while driving, pull over!

If you’ve spent much time around semi-trucks, you know they make a lot of noise. Nothing is quite as satisfying as firing up your diesel engine and hearing it roar, but other sounds, like grating metal or high-pitched squeals, can indicate potentially serious issues.

To reduce the risk of an accident, it’s important to familiarize yourself with certain sounds. By using finely-tuned listening skills in your pre- and post-trip inspections, it’s possible to diagnose and repair mechanical problems or general wear and tear before they cause a problem. If you’re a new driver, you’re probably wondering what types of sound to listen for. Here are a few of our recommendations:

1.) A high-pitched squealing or grinding noise. High-pitched squealing or grinding noises are almost always a sign of brake problems. Often, they indicate worn-down or overused brake pads. If you spend any time driving on mountain passes or another type of high elevation terrain, it’s crucial your brakes work at full capacity. The last thing you want is an emergency situation where you’re forced to roll the dice on a runaway truck ramp.

2.) Loud banging, clanging or thumping under the hood. The average class-8 semi-truck has a 14.8 liter, six-cylinder engine. That engine weighs more than 2,000 pounds and boasts more than 550 horsepower. These machines are amazing feats of engineering that feature hundreds of moving parts. They’re designed to run for 750,000 miles or more, but that’s only in ideal conditions. If you fail to regularly change the oil or perform other types of preventive maintenance, it’s only a matter of time before something goes wrong. Banging, clanging or thumping is usually the result of a problem with the engine rods or pistons. It could also point to an issue with the hoses, belts or valves.

3.) A constant whine. If you hear a constant whine that occurs alongside flickering interior lights or a loss of battery power, it might indicate a problem with the truck’s alternator. If the whine is accompanied by a rattling or grinding sound, it might be due to a loose alternator bearing.

What should I do if I hear these noises?

If you hear any of these noises while behind the wheel of your semi-truck, slow down and pull over at your next opportunity. If you’re on a mountain pass or at a high elevation, pull over immediately and call for backup. If you’re on the highway and within 15 minutes of a truck stop or a gas station, maintain the speed limit and pull over at the next exit. After you come to a complete stop, call your manager right away. These sounds don’t always indicate a serious problem, but it’s better to get things checked out than it is to risk your safety.