1991 Mercedes-Benz 420SEL Noise Diagnosis Cost

Even brand new vehicles come back to the dealership with squeaks, rattles, vibrations, noises, electrical issues, and leaks. These items can happen anytime on a vehicle, but they tend to occur in the first 25,000 miles, and after 125,000 miles most frequently. The age of a vehicle does influence the amount of noises and vibration issues it may encounter, since most components on the vehicle slowly degrade with time.

Most experienced technicians have heard the same sounds repeatedly, and they know where to look. Most often, a technician will diagnose a noise within a few minutes, and test, if possible, to ensure they have found the issue. However, diagnosing a noise can prove to be difficult, especially if the vehicle only makes noise under specific conditions. Worse yet, if the vehicle makes the noise randomly, the technician would have to spend all day driving the vehicle until the sound is heard, or, being inspecting every component on the vehicle. Mechanical noises from the engine and transmission are normally easy to identify. Noises associated with the engine and transmission can be identified through connecting a computerized scanning tool, and monitoring the conditions in the engine and transmission during the noise. This may give a trained technician an understanding of why the drivetrain is making noise, to which they must apply classroom training and experience to identify the responsible component. If the noise only occurs as the vehicle is moving, the technician will conduct a test drive and visual inspection of the vehicle. The suspension and driveline are inspected for worn or broken components. When the noise is identified, the technician should know the problem, when it happens, why it happens, and how to repair it.

Noises can come from a variety of sources, and repairs could range from a few minutes to many hours. Some noises are very simple fixes, and other can be outrageous. In many cases, brakes and suspension are the culprit, and servicing or replacing worn components typically restores the vehicle to proper operation.

We recommend bringing the vehicle to a certified shop with ASE certified, and, if possible, factory trained technicians. This will limit the amount of time needed to complete a diagnosis, and can help save cost for diagnosis. Many non-reputable shops charge diagnostic fees, and allow their non-certified helpers inspect the vehicle. It is completely acceptable to request an ASE certified technician, and ask the shop if they have a factory trained technician for your brand of vehicle.

Diagnosing a noise can be very easy, or very difficult. For instance, a specific SUV may make a rattle noise across every bump, many technicians can observe this rattle in many countries around the world, and on thousands of vehicles. However, the rattle can go undiagnosed for years, until the manufacturer, or someone in the field figures out the issue. This is not a common occurrence, but there are several cases of known noises in vehicles that are unknown in origin, and recalls may be pending.

Many DIYers can find out what is making that noise, and get it fixed properly, however, many noises are not a matter of metal on metal contact, or a squeaky wheel bearing. Quite a bit of time can be swallowed by attempting to diagnose a noise, and hoping to stumble onto the answer. The task of diagnostics should be left to a professional technician once all knowledge and tooling resources are dissolved, as damage may occur without excellent knowledge, skill, and tooling.