When your vehicle makes noises or shows other symptoms, how do you know if it needs immediate attention? Consider these guidelines:
Screeching, squealing brakes: May need new brake pads, rotor resurfacing or replacement. Some vehicle makers build in a brake-wear indication system that squeals to indicate brake pads should be replaced. If you ignore the warning, you may begin to hear grinding or groaning, which may be a sign that your brake pads are worn through and should be immediately seen by a mechanic.
Check engine light: Indicates your car should be examined at your earliest convenience. But if the light flashes, take it in right away.
Sputtering, rumbling or rattling exhaust system: May need repair or adjustment. If your car simply is louder than usual, you may have a hole in your exhaust pipe or muffler. If you hear what sounds like a box of rocks shaking when stopped at a light or stop sign, your catalytic converter may need to be repaired.
Smoking tailpipe: May be something a tune-up can fix or it could be as serious as a major engine problem. (In cold weather, it's normal for exhaust to be visible.)
Chirping or squealing under the hood: May come from a worn drive belt, which transfers power from the engine to accessories such as the air conditioner, power steering and alternator. The belt can eventually wear and slip, causing squealing that you may hear when you start or rev the engine. Replacing a belt is relatively simple and inexpensive. But if the problem is ignored, the engine may overheat, creating more damage.
Leaks: May not be a problem, if drips are small, but major leaks may require that you have the vehicle towed to a shop. Watch for bright green coolant or dark red-brown liquid, which can be transmission oil, engine oil or brake fluid. (During the summer, it's normal for water to pool under the front passenger side. This is condensation from the air conditioner.)
Engine racing, shaking or chugging: A component in the fuel or ignition systems may be failing and should be examined. Bad fuel is a less frequent cause of engine roughness.
"Smoke" from under the hood: May be a ruptured cooling system. Watch the temperature gauge. If the temperature rises, stop until the engine cools, and consider seeking immediate help.
Humming, growling or roaring: May need new tires or new wheel bearings. To determine which, slightly move the steering wheel back and forth as you change lanes while maintaining a constant speed. If the noise changes pitch while the car changes lanes, but returns to the usual noise when the car is straight, it's likely you need new wheel bearings. Don't delay taking the car to the shop; a bearing problem can render your vehicle undriveable.