Bruce Nunnally Posted March 31, 2007 Report Share Posted March 31, 2007 Tools Required • J 39570 Chassis Ear • J 41416 Ultrasonic Leak Detector Caution An assistant should drive the vehicle while the technician checks for the location of the reported condition. Otherwise, personal injury could result. To analyze a reported windnoise condition, test drive the vehicle to determine the origin of the noise. Choose a regular route with smooth and straight streets that run in all 4 directions: North, South, East, and West. The area should have little traffic or little noise in order to eliminate interference with the test. Important: Often there is one primary leak source and one or more secondary leaks that contribute to the noise condition. Repairing only one of the contributing leak sources may not completely repair the total condition but only reduce the condition. Drive the vehicle at the speed in which the noise was noticed, or until the noise is heard. Maintain safe and legal speeds. Many of the waterleak diagnosis tests are also used for the windnoise diagnosis. Most windnoise is caused either by leaking seals or by misaligned body surfaces. You can diagnose the following types of windnoise with the aid of J 41416 or J 39570 : • Wind whistle • Wind roar • Wind rush When moving at highway speeds, air pressure inside the vehicle becomes greater than the air pressure outside. When a leak occurs, the escaping air causes a hiss or a whistle. Wind roar occurs when air passes over or through an opening between the 2 body surfaces. To correct the condition, adjust the alignment to the body surfaces. Wind rush occurs when air presses over the vehicle's body, and is related to the aerodynamics of the vehicle. Wind whistle and wind roar are repairable. Rule out wind whistle and wind roar before concluding that the wind noise is due to wind rush. Use the following inspections in order to aid in diagnosing wind whistle or wind roar: Note the details for wind noise: • The perceived location • The location where the noise is loudest • When the noise occurs • The vehicle speed • The interior fan speed • The position of the windows • What the noise sounds like Inspect the vehicle for the possible cause of the windnoise. Test drive the vehicle and determine if the windnoise is external or internal. Perform a visual inspection of the following components: • Loose fasteners • Torn weatherstrips • Broken weld joints • Sealer and/or adhesive skips Tracing Powder or Chalk Test Clean the weatherstrips and the contact surfaces with cleaning solvent. Apply powder or chalk in an unbroken line to the contact surface of the weatherstrip surrounding the perimeter of the suspected areas. Close the panel completely without slamming the panel. Closing the panel completely presses the weatherstrip firmly against the mating surface. Inspect the applied line on the weatherstrip. The applied line is marred where contact is good. A corresponding imprint is on the mating surfaces. Gaps or irregularities in the powder or the chalk line on the mating surfaces indicate the areas with a poor seal. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
JohnnyG Posted March 31, 2007 Report Share Posted March 31, 2007 Thanks for posting that piece of info. I really didn't realize that there were at least 3 distinct types of wind noise, leave it to engineers to figure that out. Unfortunately, it seems that I have the unrepairable condition - wind rush. The noise is not a whistle, so that one is automatically ruled out by the nature of the sound. Nor does it sound like a leak of any kind. Wind roar was a possibility, but all surfaces are properly aligned. Except for the biggest one that is, the gap between the hood and the windshield, occupied by the wiper blades. Nothing on earth can clean up that area of turbulence. There is no damage or misalignment in that area, but I'm pretty certain it is the source of the noise. I can hear the noise through the windshield glass, and was able to reduce it slightly by filling all the small gaps around the chrome and black rubber trim using black RTV. I was thinking, can some sort of deflector be attached at the front of the hood that might divert some of the air away from that area? Has anyone seen a "bug deflector" on the hood of an STS? I'm thinking that changing the aerodynamics and rate of air flow in that area would quiet things down a little. If any turbulence occurred around the deflector, it should be far enough away from the driver to be unnoticeable. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Ranger Posted March 31, 2007 Report Share Posted March 31, 2007 Caution An assistant should drive the vehicle while the technician checks for the location of the reported condition. Otherwise, personal injury could result. DUH. Lawyers Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted March 31, 2007 Author Report Share Posted March 31, 2007 There is a suggestion about using masking tape over gaps that you think are causing wind noise, to validate the source of the noise. Then remove the tape and adjust the body panels or trim in order to fix. Also this test: Air Pressure Test Mask off both the pressure relief valves. Close all the windows. Turn the vehicles ventilation fan to the on position, with the selector on high speed and in the defrost mode. Unlock and close the doors. Listen for escaping air along the door and the window seals with a stethoscope or a length of heater hose. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
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