EXPERTEC TSB (39-2)

GENERAL INFORMATION

A. Beginning the repair

B. Responsibility of the service adviser

THE WIND NOISE CONDITION

A. Questions specific to all wind noise conditions

B. Analyzing the wind noise

1. Door alignment
2. Outside sports mirrors
3. Areas and percentages of reported objectionable wind noise
4. Classifications of wind noise

THE ROAD TEST - DIAGNOSTIC TECHNIQUES

1. Compressed air and soapy water test
2. Dollar bill test
3. Flashlight or shop light test
4. Sonic tester and tone generator
5. Visual inspection
6. Tracing powder or chalk test
7. Air pressure test
8. Soap suds or bubble test

TOPICS TO BE COVERED IN NOVEMBER ISSUE

1. External wind noise

SEALERS AND RELATED PRODUCT USAGE

A. Adjustments and sealing repair operations

B. Stationary glass repairs

C. Vinyl reveal molding

SPECIFIC AREAS

A. Windshield

B. Front door

C. Rear door

D. Back glass

BEGINNING THE REPAIR

1. The repair process actually begins: when the customer brings the vehicle to the dealership or repair shop and the condition is written up on a repair order. A lot of valuable information can be obtained by the service adviser during his/her initial contact with the customer if questions regarding the vehicle's condition are channeled in the right direction.
2. Responsibility of the service adviser: As the liaison between the customer and the repairman, the service adviser obtains all needed information and writes it in a common service language to assist everyone in the repair cycle in making a lasting leak repair in an efficient manner the first time. The service adviser should keep in mind that the cause of a wind noise can vary between body styles and from vehicle to vehicle within a given body style. It is also possible that a reported condition on a given vehicle may never be encountered again on any other vehicle.

They are as follows:

1. What? Wind noise
2. Where? Specific area(s) leak(s) are located.
3. When? Under what condition(s) does the leak/noise occur?

A. QUESTIONS SPECIFIC TO ALL WIND NOISE CONDITIONS

To assist in diagnosing and repairing the owner's vehicle quickly, the following information should be obtained:

1. What specific noise is objectionable?

   A. Whistle?

   B. Fluffer?

   C. Rush of air?

2. Under what condition does the noise occur?

   A. In motion?

   B. Heater/AC blower motor on or off?

3. Does the noise appear to be....

   A. Air leaving the body?

   B. Air passing over the body's exterior surface?

4. In which occupant seating position of the vehicle is the noise most objectionable?

   A. Front seat

   • Driver's seat?
   • Center Passenger's seat?
   • Right passenger's seat?

   B. Rear seat

   • Left passenger's seat?
   • Center passenger's seat?
   • Right passenger's seat?
5. At what speed does the specific noise first occur?

   A. Less than 10 miles per hour?

   B. 10-34 miles per hour?

   C. 35-55 miles per hour?

   D. Over 55 miles per hour?

6. In what general area does the noise appear to originate?

   A. Front of vehicle

• Grille
• Bumper
• Hood
• Fender
• Shroud (Cowl) area
• Windshield

B. Sides of vehicle

• Windshield pillar
• Upper
• Center
• Lower

C. Rear of vehicle

• Rear window
• Tulip panel
• Tailgate/window (wagons)
• Quarters
• Rear bumper
• Roof rack (wagons)

B. ANALYZING WIND NOISE

When a vehicle is in motion, it strikes the air causing it to bend around the vehicle and deflect around the windshield pillars (Fig 2 ). When this occurs, areas of high and low pressure are then created. It is the difference between the pressure build up that varies levels of sound pitches. As air strikes the base of the windshield, it backs up. This causes a low pressure center to develop outside the vehicle around the front pillars and side windows.

The amount of low pressure build-up along the sides of the vehicle is increased by the impact speed of the air as it strikes against the windshield surface. The faster the vehicle is traveling, the greater the pressure difference becomes.

This pressure build-up at the windshield causes the air flow that is filtered through the vehicle vents and/or air conditioner to build up high pressure inside of the passenger compartment. The faster the vehicle is traveling, the greater the inside pressure becomes. The speed of the vent fan will also have an effect on pressurization of the passenger compartment.

The pressure pushes outward on the glass and other seals. This situation is not normally a problem, but if a door or window is out of alignment, leaks can develop and cause a wind whistle.

The high inside pressure and low outside pressure is separated only by vehicle's sheet metal panels, glass, weatherstrips and body seals.

When an opening is created at a joint at any of these areas, the high inside air pressure will move toward the low outside pressure area to create an air leak.

The shape of the opening would then determine if an audible noise or whistle can be heard. It may require a specific vehicle to create enough high pressure to break the seal.

The vehicle has a large area, plus a number of exterior attachments in which air must move around. As a result, some rush of air will be heard and is considered normal.

Examples Are:

1. Door alignment - a door should fit properly into the vehicle's body opening for several reasons:

   A. Appearance

   B. Ease of operation

   C. Smooth quiet air flow.

   A vehicle door that is not properly aligned will act similar to an air scoop. The inside area of the door jamb will become pressurized and create air turbulence which may be transmitted as noise inside of the passenger compartment (Fig 3 ).

2. Outside sports mirrors - they are shaped similar to a bullet in front, and flat across s the face or rear.

   When a vehicle is moving, its outside mirrors strike and bend the air around it. This flow of air around the body of the mirror can create a low pressure area or vacuum across its face allowing turbulence to build up (Fig 4 ).

   Because of the styling design of the sports mirror, the noise cannot be eliminated.

   The noise source can be verified by taping over the face of the mirror and then subject vehicle to the same road conditions.

   The high pressure inside air moves toward the low pressure (vacuum) area through the door belt sealing strips and/or any other voids in the mirror head or inside the door. If the air passage is shaped just right, an objectionable air noise can be heard. Thus, you could have a wind whistle and wind roar condition.

3. Areas and percentages of reported objectionable wind noise (Fig 5 ).

   It is estimated that 7% of all reported objectionable wind noise conditions can be located at the front end (bumpers, grille, hood and fenders) of the vehicle.

   Another 90% of the reported objectionable wind noise conditions are located in the area between the dash panel and the rear edge of the door or center pillar.

   The remaining 3% of those reported conditions were located between the rear edge of the door or center pillar area to the rear of the vehicle (usually vent window seals, luggage racks or tailgates and wind deflectors).

4. Classifications of wind noise - it is important to note that wind will not create a noise until it is forced to change directions or is forced to move around an object. Wind noise may be classified into three categories:

THE ROAD TEST

To analyze a reported wind noise condition, a test drive in the vehicle is necessary due to the many variables that could singularly or collectively be attributed to creating the objectionable wind noise condition.

FOR SAFETY REASONS: An assistant should drive the vehicle while the technician checks for the location of the reported condition(s). In addition, the following items should be taken for utilization by the technician during the test drive to aid in pinpointing and marking area(s) of the leak:

1. Mechanics stethoscope or vacuum hose.
2. Masking tape (2" in width).
3. Strip caulk.
4. China marking pencil.
5. Screwdriver.

First determine if the noise is an objectionable wind noise as opposed to normal or standard sounds.

If noise can be heard with the door glass lowered and vehicle is being driven, it is EXTERNAL WIND NOISE.

Locating an EXTERNAL WIND NOISE condition can be accomplished by taping various moldings and gaps until the noise is eliminated to pinpoint the exact cause of the noise.

If noise cannot be heard with the windows lowered, this indicates a body seam is leaking or a sealing surface such as a glass to weatherstrip or door weatherstrip to door is poor. Internal wind noise is air leaving the body.

INTERNAL WIND NOISE

The first step in locating the source of internal wind noise is to tape off the body lock pillar pressure relief valves. This will cause air presure to build-up inside the vehicle and enhance the wind noise. Trace the suspected seal using the stethoscope or section of vacuum hose to locate the leak area.

Temporarily repair the condition with masking tape (Fig 6 ). Adjust tape as required. Continue testing to determine if noise has been eliminated or other leak areas exist.

When all reported leak conditions have been located, return to shop and make permanent repairs utilizing proper alignment techniques and sealing materials as required.

1. COMPRESSED AIR AND SOAPY WATER TEST

Another form of localized testing is performed utilizing compressed air and a soapy water solution.

Using a mixture of liquid soap and water, or a foaming type glass cleaner, apply it directly to the exterior surface of the suspected leak area.

Apply compressed air (30 P.S.I. - 205 kPa) to the suspected area from inside of the vehicle outward at the panel joint, or suspected seam or seal (Fig 7 ).

Large bubbles will appear outside as the exact leak point is reached.

2. DOLLAR BILL TEST

Place a dollar bill or similar size piece of paper between weatherstrip and contact surface, then close door, lid, etc. (Fig 8 ).

Slowly withdraw the bill or paper after panel is closed, to check the amount of pressure on the weatherstrip.

There should be a medium amount of resistance as the bill or paper is slowly withdrawn. Continue around the entire seal area. If there is little or no resistance, it indicates there is insufficient contact to form a good seal. This test may indicate that the door, glass or weatherstrip is out of alignment.

3. FLASHLIGHT OR SHOP LIGHT TEST

A bright light may be used to check panel seams and openings. Have a helper move light along suspected seam such as the rear wheelhouse, and check for light leaks inside the trunk.

4. SONIC TESTER AND TONE GENERATOR

The sonic tester and tone generator (J 23455.01) is a useful tool available for testing seams, seals and weatherstrips.

The sonic tester consists of a microphone pickup that is monitored through a headset and a tone generator (transmitter) that is placed inside of vehicle or in the trunk. Pass the pickup head along each seam or weatherstrip until a noise is detected.

5. VISUAL INSPECTION

The source of the condition is not always in the same location where the noise is heard. The visual inspection should begin and center around the suspected area(s).

Inspect vehicle for:

1. Misaligned components
2. Loose fasteners
3. Torn weatherstrips
4. Broken weld joints
5. Sealer and/or adhesive skips

6. TRACING POWDER OR CHALK TEST

Tracing powder or chalk test is best suited for checking weatherstrip contact of doors, rear compartment lids, door glass, sunroof, vista vents, hatch roof and tailgate areas. Tracing powder is conveniently available in aerosol cans.

Spray powder or apply soft chalk to the weatherstrip contact surface and close the door, hatch, lid, etc. Do not slam. Check the weatherstrip mating surface for unbroken areas of powder or chalk.

Areas that have a 1/8" or 3.17 mm skip in the powder or chalk line should be considered leak areas.

Close the panel completely, without slamming, to press weatherstrip firmly against its mating surface, and then, reopen.

The applied line on the weatherstrip will be marred where there is good contact. There will be a corresponding imprint left wherever the weatherstrip touched its mating surface.

Any gaps or irregularities in the powder or chalk line on either surface indicates a poor seal.

7. AIR PRESSURE TEST

Wind noises are often caused by high pressure air escaping whenever the vehicle travels at road speed. However, this condition can often be recreated without the vehicle moving by performing the following static test.

To recreate this effect, proceed as follows:

1. Completely mask off both pressure relief valves
2. Turn on the vehicle's ventilation fan, roll up all windows and close all openings (doors, sunroof, etc.). This will cause an abnormal amount of high pressure to build up inside of the vehicle. The buildup of air pressure will travel through any voids or poor seals.
3. With a stethoscope or a length of heater hose, listen for escaping air from the outside of vehicle along the door and window seals.

A smoke or dusting powder test can be used in the same manner as the above test procedure, except instead of listening for the air leak area(s), the exact location can be seen as the smoke or powder travels through the void or bad seal. Dusting powder often leaves a tell-tail path in the void area.

8. SOAP SUDS OR BUBBLE TEST

This test can be performed using two different methods:

1. The FIRST METHOD is similar to the smoke or dusting powder test:
   1. The interior of the vehicle is pressurized and a soapy solution or a foamy glass cleaner is applied to potential leak areas on the outside of the vehicle.
   2. Bubbles will appear at the void or leak point as the air escapes, pinpointing the exact area.
2. A SECOND METHOD of detecting the leak is the following:
   1. Apply the soapy solution or foam glass cleaner to the suspected leak area (windshield area, body joint, taillight, etc.).
   2. Apply air pressure with an air hose from inside of the vehicle at the suspected leak area. Do not exceed 205 kPa (30 psi).
   3. Bubbles will appear at the voids, thereby pinpointing the leak area.

This second method is generally used for water leak diagnosis but can also apply to some wind noise diagnostic testing procedures.

External wind noise and other related topics will be covered in the November Service Guild Issue.