Interior - Tapping Noise In Corner of Dash
89chevy05Number: 89-101-10
Section: 10
Date: MARCH, 1989
Subject: TAPPING NOISE IN CORNER OF DASH
Model and Year: 1987-89 S/T TRUCKS
TO: ALL CHEVROLET DEALERS
Some 1987-89 S/T Trucks may experience a noise from the cowl area located around either of the front dash speakers. The noise has been described as a tapping or creaking noise similar to tapping a pencil lead on the windshield.
This condition occurs primarily at ambient temperatures below 45 degrees Fahrenheit. Therefore, vehicles which sit inside a heated facility during repair should be "cold soaked" prior to verifying the repair.
Repair Procedure
Apply repair procedure exactly as described in Chevrolet Bulletin 86-58 (Section 10) dated April, 1986, which has been reproduced in this bulletin for your convenience.
IMPORTANT: Windshield replacement will not resolve the situation.
For repairs to vehicles under warranty, use:
Labor Op: T7230
1983-86 Models -
Labor Time: .6 Hr per side
1987-89 Models -
Labor Time: .8 Hr. per side
NOTE: On 87-89 vehicles, the location of the one inch hole will encompass a small weld. Additional time has been added to the labor operation to take this into account. Be sure to cut through only the first layer of sheet metal as specified in Step 9 on the bulletin.
IMPORTANT: Dealers who have vehicles that are not repaired by this procedure should contact Technical Assistance for further assistance.
Subject: COWL POPPING NOISE
Model and Year: 1983-86 S/T TRUCKS
Number: 86-58
Section: 10
Date: APR., 1986
TO: ALL CHEVROLET DEALERS
On some S/T Trucks operating in low ambient temperatures, a condition may exist where a snapping or "popping" noise is heard coming from the cowl. This noise is caused by an "oil can" effect between the windshield frame and the door frame. The service procedure for eliminating the noise is as follows:
1. Remove the windshield wipers and radio antenna.
FIGURE 1:
2. Remove the cowl vent panel fasteners (Figure No. 1).
FIGURE 2:
3. Place tape on the fender edge and cowl panel edge to prevent paint damage (Figure No. 2) .
4. Disconnect the windshield washer hose from the nozzle.
5. Remove the cowl panel, being careful not to scrape the cowl on the inner hood edge or fender.
6. Pull back the hood hinge seal to expose the windshield frame and close the hood.
FIGURE 1:
7. Measure 1 1/4" down from the bottom of the windshield and make a horizontal mark on the windshield frame inboard of the cowl screen lock tab (Figure No. 1).
8. Measure 7/8" inboard from the cowl screen lock tab and make a vertical mark through the line made in the previous step.
9. Center punch the windshield frame at the point the lines intersect. Use a one inch hole saw to cut a hole in the windshield frame (cut through only the first layer of sheet metal) and remove the circular piece of metal that remains from cutting the hole. DO NOT CUT THE SECOND LAYER PANEL.
10. Drive the door frame (the second layer of sheet metal) down with a punch approximately 1/4" all the way around the hole.
11. Paint the bare metal edges left from cutting the hole with a zinc rich primer.
12. Completely fill the hole with black RTV, GM P/N 1052917, or equivalent and level for good adhesion and appearance.
13. Follow Steps 6-12 on each side of the vehicle.
14. Reinstall the hood hinge seals in their original position to prevent water leakage into the cowl. If it is necessary, additional adhesive (3M weather strip adhesive P/N 08001 or equivalent) should be used to secure the hood hinge seal.
15. Reinstall the windshield washer hose, cowl vent panel, radio antenna, and windshield wipers, and remove the protective tape from the fender and cowl vent panel.