Volkswagen ID.3: Technical data. Volkswagen equipment for localising noises

• Design of ultrasonic tester V.A.G 1842S
• Example of procedure for identifying noises using ultrasound

Design of ultrasonic tester V.A.G 1842S

Design of ultrasonic tester -V.A.G 1842S-

♦ Plastic case

Example of procedure for identifying noises using ultrasound

Example of procedure for identifying noises using ultrasound

Clattering, knocking and humming sounds

The low-frequency noises such as dull knocking (e.g. when the headliner strikes against the roof) or low-frequency humming noises do not generate any ultrasound signals or only weak ultrasound signals. Therefore, the combined probe should be used to detect and amplify the audible noise and ultrasound simultaneously. This probe is connected to the receiver via two connectors. Due to the high directivity and the possibility to amplify the sound, the noises can be localised very precisely although they are not very intense or located behind trims.

Note

Headphones are mandatory to avoid being confused by the whistling noises emitted by the unit itself.

Noises from the engine compartment or body

are localised using an ultrasonic receiver -1- or a microphone with magnetic mountings -1-. These are secured as a pair near the suspected origin of the noise. The supplied extension cables are used to connect them to a changeover switch on the receiver in the vehicle interior. The noise is analysed during the road test and the origin is determined by switching between the sensors and by changing their position.

Caution

It is recommended to secure the sensors and cables using adhesive tape to avoid any damage to them or to other components when the position of the sensors is changed. Do not secure the sensors and cables near any heat sources.

Localising small leaks in the intake connecting pipe and exhaust system

The receiver allows for clearly localising leaking joints, loose clamps, porous or defective vacuum lines and damaged seals when the engine is running. If there is a leak, a whistling/intake sound can be heard through the headphones.

These small leaks may cause noises at increased engine speed.

First, inspect the entire engine compartment using the receiver set to maximum sensitivity and with headphones connected.

A strong air flow generates higher ultrasound levels. In this case, reduce the sensitivity of the unit accordingly. After the origin of the sound has been identified roughly, the exact location is determined using the unidirectional probe or the pointed attachment to ensure a higher accuracy.

Noises from mechanical components or bearings

Nearly any friction between metal components generates ultrasound which becomes audible and visible using the ultrasonic tester.

First, identify the potential origin of the noise using the receiver with headphones connected. Set the sensitivity on the receiver to a level at which the noise can be heard well but is not too loud.

The status LED must be in the medium range (yellow LED) at most. However, the intensity of the noise itself is the deciding factor. Weak signals may be audible even if they are not displayed. The closer the receiver is moved towards the source of the noise, the stronger is the received signal. Fit the unidirectional attachment (with pointed attachment as necessary) to localise the source of the noise more precisely.

After the source of the noise has been determined, it is to be verified by holding the tip of the ultrasonic tester for structure-borne noise against the component.

Ingress of air into vehicle interior

This type of leaks can be identified during a road test using the receiver and the unidirectional attachment. This test always requires two mechanics. Any search for leaks on the driver side during a road test bears a certain risk. In this case it is safer to perform a static test using the sender in the vehicle interior and the receiver outside the vehicle. In this way, air leaks can be localised by sensing the seals of doors, windows and panoramic tilting sunroof.

Air leaks may cause whistling noises and dynamic noises in the vehicle interior.

WARNING

♦ Always adhere to the safety precautions when performing road tests which include 2 mechanics. One mechanic drives the vehicle while the other mechanic performs the test.

♦ Always adhere to the traffic rules when performing road tests on public roads. The vehicle safety as well as the safety of any other road users must never be impaired by the test.

Technical data. General procedure for identifying noisesTechnical data. Borescope VAS 6748A