K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
2.
At what speed does the noise occur?
3.
Is the heater/AC blower motor "ON" or "OFF"?
4.
In what general area does the noise appear to originate?
5.
Does the vehicle have a bug deflector or roof rack?
VISIBLE INSPECTION:
1.
Inspect the vehicle for:
A.
Misaligned components.
B.
Torn weatherstrips.
C.
Broken weld joints.
D.
Sealer and/or adhesive skips.
These indicators could be the cause of air leakage, repair if necessary before proceeding with the bulletin.
2.
Measure the door's fit (refer to the appropriate Service Manual Section, 10A1 "Door Adjustment", for door fit specifications).
ROAD TEST
1.
The vehicle should be driven under the conditions described by the customer in the "customer write up" section in order to hear the wind noise.
Safe legal speeds should never be exceeded.
2.
While driving the vehicle, place a stethoscope around the sealed areas of the door and glass.
3.
Temporarily repair the leakage area by sealing the area with masking tape.
4.
Continue to test drive the vehicle to determine if the wind noise has been eliminated or if other leaks exists.
DOLLAR BILL TEST
1.
Place a dollar bill or similar size piece of paper between the primary weatherstrip and seal surface and close the door.
2.
Slowly withdraw the paper and check the amount of pressure on the weatherstrip. There should be some resistance to ensure a positive seal.
3.
Continue around the entire seal. If there is little or no resistance, it indicates that there is insufficient contact to form a good seal. This test may
indicate that the door, glass, or weatherstrip is out of alignment.
COMPRESSED AIR AND SOAPY WATER TEST
1.
Apply a mixture of liquid soap and water or foamy type glass cleaner directly to the exterior surface of the suspected leak area.
2.
Apply approximately 30 psi (205 kPa) of compressed air to the suspected area from inside the vehicle.
3.
Large bubbles appearing will reveal the exact leak point.
CHALK OR TRACING POWDER TEST
1.
Spray powder or apply chalk to the weatherstrip contact surface. This test is best suited for checking weatherstrip contact to the seal surface.
2.
Close the door gently.
3.
Open the door and check the weatherstrip seal surface for unbroken areas of powder or chalk. Areas that have an 1/8 in. (3 mm) skip in the powder
or chalk should be considered leak areas.
When the suspected wind noise locations have been diagnosed, refer to the following sections of this bulletin for the proper repair procedure of that area.
II. REPAIR OF DOOR LOCATIONS
