Diagnosis Techniques
FIGURE 7:
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 (Figure 7).
FIGURE 8:
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. (Figure 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There should be a medium amount of resistance as the bill or paper is slowly withdrawn.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 the 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:
a. Misaligned Components
b. Loose Fasteners
c. Torn Weatherstrips
d. Broken Weld Joints
e. Sealer and/or Adhesive Skips
6. Tracing Powder or Chalk Test
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 inch 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
Windnoises 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:
a. Completely mask off both pressure relief valves.
b. 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.
c. 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.
Soap Suds or Bubble Test
This test can be performed using two different methods.
The FIRST METHOD is similar to the Smoke or Dusting Powder Test:
a. 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.
b. Bubbles will appear at the void or leak point as the air escapes, pinpointing the exact area.
A SECOND METHOD of detecting the leak is the following:
a. Apply the soapy solution or foam glass cleaner to the suspected leak area (windshield area, body joint, taillight, etc.).
b. Apply air pressure with an air hose from inside of the vehicle at the suspected leak area. Do not exceed 205 kPa (30 psi).
c. 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 windnoise diagnosis testing procedures.
External Windnoise
Visually inspect vehicle in suspected leak area(s) for loose trim, loose fasteners, and poorly aligned panels or components. Grilles may whistle under certain conditions.
PERFORM THE FOLLOWING TO DIAGNOSE AN EXTERNAL WINDNOISE:
a. Road test the vehicle to determine if the noise is coming from the front of the vehicle.
b. If the noise is coming from the front end, mask off the entire grille, headlight bezel areas and windshield upper reveal molding. Care must be taken not to allow masking to restrict air flow and vehicle overheating.
c. Retest the vehicle if the noise can no longer be heard.
d. Remove a small section of the masking tape and retest for the noise.
e. Continue this procedure as required until the noise has been located.
f. Take vehicle back to shop and make permanent repairs.