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Troubleshooting those weird noises coming from your Porsche can help you determine needed repairs. It's important that you listen to what your car is trying to tell you.
Although many people still use the old broomstick-held-to-the-ear method of zeroing in on noises, the best method these days is a stethoscope. Indispensable in finding the source of a sound, it's also a lot easier to place it where you want it than the clunky end of a broomstick.
Here are a few general guidelines to what your Porsche's noises might mean:
BANG: A sharp, startling sound, like a rifle shot, means you're dealing with the dreaded backfire. You'll probably be able to trace this to something that's causing a rich air/fuel mixture.
In the past you might have zeroed in on a heavy carb float, but today think about faulty signals from coolant temp or O2 sensors. The catalytic converter may also be damaged.
Another possibility is a clogged monolithic converter blowing through. This will only occur once and will be accompanied by an amazing increase in power. If your car has air injection, perhaps the diverter valve is no longer diverting.
BOOM: A hollow, low-frequency sound/sensation, this makes you feel as if you're riding inside a metal drum and the atmospheric pressure is rapidly changing between positive and negative.
On rear wheel-drive cars, check out the driveshaft and its u-joints because if it's spinning out-of-true, it will cause waves that push up on the floor of your car.
BUZZ: An annoying "bzzzzzzzzz" sound, like a trapped insect, can usually be traced to unfortunate positioning of interior trim parts. Have somebody else drive while you press, pry and pound on every likely spot.
CHIRP: This sounds like birds are nesting under your hood. You can probably blame a maladjusted or misaligned belt, but don't ignore the idler pulley. Or, it could just be your tires when you hit second gear.
CLANG or CLANK: This sound couldn't possibly be emitted by any light, flimsy parts. It's coming from a heavy, essential component, such as a set of gears. A good example is the sound a bad rear axle pinion bearing makes when you drop the transmission into Drive, then Reverse.
CLICK or CLACK: This sounds like 007 working the slide of his Beretta automatic. When in an engine, it's typically repeated rhythmically.
With OHV, perhaps a stuck lifter is allowing clearance in the pushrod/rocker valve, or maybe a solid lifter is just out of adjustment. On carbureted cars, check out the fuel pump before you start opening up the motor.
When emanating from the nether regions of the front end during a turn, this sound may be traced to an outboard CV joint.
CLUNK: A heavy bumping sound, softer than a clang, usually indicates you should look at suspension bushings, including shock or strut mounts. Or how about a loose strut gland nut?
FLAPPING: If it's not due to a colony of bats under the hood, maybe a belt's coming apart. Fan interference is another possibility. Regardless, this is a visual inspection sort of thing.