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Tuesday, January 3, 2012

KATE ON CARS: Those Winter Squeaks & Rattles part 2


By Kate Jonasse

A quick note before we start: I want this column to be fun, interesting and relevant. To do this I'd like my readers' feedback. Please send your thoughts, comments, car questions, and ideas for future columns to me via email at Please put “Gazette Reader” in the heading. Thanks for reading.

It seems that every day I hear at least one car driving down the road with a belt squeal. You've probably heard it – often sounds like a large bird trapped under the hood. What causes this?

Well, engine belts make noise for a few reasons – generally they can squeal, shriek, or chirp when they get wet, dry, loose or worn. When engine accessory belts get wet from rain or driving through a puddle they can squeal and shriek like crazy until they dry off. (Sometimes you can stop this noise temporarily by accelerating briefly and quickly – step on and off the gas pedal to speed up the engine and help dry and seat the belt.) Also, overly dry, cracked or loose belts can cause noises like that whenever the engine is running, whether your car is moving or not. What should you do if your car is making a noise like this? Have your trusted auto repair shop inspect it.

Finding the source of squeaks in a car or truck is an art and a skill. After years of practice working on cars, a technician can develop a certain 6th sense about noises. But we still rely on special tools and test procedures to help out. Some noises are easy to find, sometimes we need to pull out the big guns on trickier ones.

Your shop's technician may first use her/his stethoscope to poke around and see where noises are the loudest. This is a really helpful tool for belt and engine noises, but doesn't work so well during road tests. Can you imagine a technician with a stethoscope hanging on underneath a car listening for noises while another one drives it over bumps looking for noises? This sounds like something you'd hear from a caller on “Car Talk.”

Chassis “Ears”
Actually, for noises that happen only when you're driving we use something called “chassis ears” (pronounced “chassee” ears, with the “a” like “apple”). This tool consists of a setup with a controller box and a bunch of remote transmitters - see the picture in this article for a visual. The transmitters are placed under the car or under the hood on components that could be making noise, like on the steering or suspension components such as struts and control arms. The box is used to select which transmitter the technician want to listen to at a given time. The transmitter that picks up the loudest noise is usually the one closest to the source of the noise. This is a two person job – one person drives and the other listens (from the passenger seat) to the noises and switches the box to different transmitters. It can be a time-consuming procedure to set up the chassis ears but they work really well to help pinpoint noises.

Bottom line is: if your car is making a funny noise it is trying to tell you something – please for your safety don't ignore it. Damaged belts can break and cause problems like loss of charging system operation, loss of power steering, or the dreaded and costly overheating which can cause serious engine damage. Play it safe and contact a professional at the first sign of unusual car noises.

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