Mercedes-Benz S400 Car is making a noise Inspection at your home or office.

Common reasons for this to happen:

The first step in identifying the cause of a noise involves pinpointing its location. Here are the most common and concerning noises that cars make -- along with conditions that often create them -- according to their location within the car.

Under the Hood:

• Belts and pulleys: If there is a screeching noise with a repetitive tone, it may indicate the serpentine belt is worn or the engine pulley that drives the belt is freezing up. This belt is responsible for providing power to multiple systems in your car, including the air conditioning compressor, alternator, power steering pump, water pump, and radiator fan. Belt noises are usually quickly identified and typically vary with engine speed.

• Hoses: There are a host of different hoses beneath your hood, which can develop holes or cracks over time and affect your engine’s performance. If you can hear a hissing noise or see coolant beneath the front of your car, a worn hose is the likely culprit. The mechanic will carefully trace any liquids to the source or listen for the escaping of air until they can identify the source of the problem.

• Internal engine parts: If you hear a tapping or metallic slap, there may be an issue with the way your engine is rotating parts. Possible causes are low motor oil levels or an issue with timing or engine calibration. If you suspect an internal engine noise, it is wise to have the vehicle inspected by one of our expert technicians as soon as possible.

Under the Car:

• Brakes and wheels: If a high-pitched squealing is present, the brake pads are likely in need of replacement. A deeper growling or grinding noise usually indicates pads that are past due for replacement, and may require more parts and labor than a standard brake job.

• Exhaust system: When a clanking noise is present beneath your car, or its normal running noise is significantly louder, there is potentially an issue with your exhaust system. The mechanic will review the individual pieces of the system from the tailpipe to the front and check that all clamps are secure with a bit of space from the chassis to identify the source of the noise.

• Suspension system: This system is made up of many moving parts, bushings, and joints that can produce irregular clunking noises when any part becomes worn. To verify there is an issue with your suspension system, the mechanic will inspect the entirety of the system, which will usually involve lifting the car.

Outside the Car:

• Aerodynamic interference: Over time, parts on your exterior can loosen or become caked in debris, ultimately resulting in odd noises that often resemble a low rumble or whir. The sound is often intermittent, increasing with speed and sometimes stopping entirely. Frequent culprits are the heat shield and the dust shield, although just about any part of your car’s body could be the cause.

• Tires: If there is a humming sound that consistently increases with acceleration and stops when your car is not in motion, your tires may be responsible. A quick check of the condition of tread, as well as the tread depth itself, may reveal the issue in short order.