ROOF TO 'B'/'C' PILLAR CRACK (REPAIR PROCEDURES OUTLINED). GMC Truck S15 Pickup - 2WD 1985

For 1990-2009 cars

# ROOF TO 'B'/'C' PILLAR CRACK (REPAIR PROCEDURES OUTLINED)

#### SUBJECT: ROOF TO PILLAR CRACKS (REPAIR CRACKS)

#### MODELS: 1982 - 1992 S/T PICKUPS AND TWO-DOOR UTILITY VEHICLES

The joint between the roof and "B" or "C" pillar on some 1982-1992 S/T pickups and two door utility vehicles may exhibit a hairline crack in the joint seam. If this should occur, rust could develop in the joint. The seams join the roof panel to the body side panels. There are seams at the truck "B" pillar, behind the front door opening. S/T extended cab and two-door utility vehicles have an additional seam at the "C" pillar, behind the rear quarter glass.

Some 1984-1992 vehicles may already have welds as described in this repair procedure. If cracks have occurred in these vehicles, it will be necessary to grind out the existing welds and repair as stated below.

#### SERVICE PROCEDURE:

It the "B" pillar or front of the "C" pillar seam on the S/T extended cab or utility is to be repaired, the top cap on the quarter window reveal molding should be sliced free and taped back out of the way (refer to figures 1 and 2). This is done by sliding a sharp knife edge UNDER the molding to cut it free.

#### Note: Do not damage painted surfaces. Do not distort molding, as the molding will have to be bonded back in place.

Also, peel back a portion of the drip gutter seal to expose the seam inside the front door opening. The "B" pillar welds on the pickup and utility will be similar. The extended cab pickup requires an extra weld at this pillar (refer to figures 3, 4, and 5 for weld locations).

1. Clean the area of the affected joint seam with grease and wax remover (DuPont 3919 Prep-Sol or equivalent).

2. Remove the paint down to the bare metal two inches on each side of the affected seam using an 80-grit disc.

3. Using a knife or pointed tool, remove all paint and sealer from the seam. Also remove the sealer in the door opening at the front of the "B" pillar (figure 3, section A-A). Some 1983 trucks may already have a weld in the door opening. If this is the case, a MIG weld is not needed here. It is important that all sealer and paint be removed from the seam. Failure to do so may result in weld spatter or pitting.

4. Isolate the repair area by placing a drop cloth over the surrounding finished panels and glass areas to prevent accidental weld spatter.

5. Using a MIG welder with 0.023" steel or silicon bronze filler, apply 10-15 mm (0.25 - 0.40 in.) welds at the "B" pillar as shown in figures 3 and 4. The "C" pillar weld on the utility should extend from the rear radius to the end of the seam at the tailgate glass as shown in figure 5. This weld is approximately 30 mm (1.2 in.) long.

One source for MIG welders is the GM Dealer Equipment Program. Refer to your current GM Dealer Equipment Catalog or call 1-800-GM TOOLS.

#### NOTICE: Care must be taken to minimize the amount of heat input to the panels to prevent distortion of the roof panel and/or degradation of the quarter window urethane bonding material.

6. Finish the welds flush with the exterior surface. The panel should be allowed to cool from welding operation prior to finish to minimize heat input and possible panel distortion. Cooling between rough finish and final finish is also recommended.

7. If the weld in the door opening provides a poor gap appearance with the door closed, it should be dressed to provide an acceptable appearance.

8. Feather edge the paint using standard paint preparation procedures.

9. Metal prep the bare metal thoroughly using DuPont 5717 metal conditioner or equivalent.

10. Mask off the surrounding area and spray on an acrylic primer, using DuPont 215S Acrylic Primer or equivalent.

11. Apply primer surfacer. Allow primer to air dry or bake at 180 degrees F for 20 minutes.

12. Sand primer with 360-grit dry followed by 400-grit dry.

13. Clean panel with solvent. Use DuPont 3812, or equivalent.

14. Apply 3M #5900 sealer, or equivalent to the joint. This is a two- component material used for flexible parts repair.

#### NOTICE: A flexible sealer must be used, A rigid body filler will result in future cracking.

15. Follow the sealer manufacturer's instructions for application and dry time. The material should be applied into the joint and the excess removed immediately. Care must be taken not to damage the primer previously applied.

#### NOTE: Sealer should not be applied over the MIG welds.

16. Apply 3M #5900 sealer or equivalent over the weld in the corner of the door opening to seal any opening between the roof, side, and door frame.

17. Apply a paint adhesion promoter (DuPont 222S or equivalent) and allow to dry.

18. Follow recommended paint repair procedures for acrylic paints.

19. Using a vinyl adhesive, bond utility quarter window reveal molding back into place using Krazy Glue@ or equivalent. Care should be taken to ensure that the sharp front corner of the reveal molding is tight to the body to prevent it from being ripped loose by car wash brushes, etc.

#### WARRANTY INFORMATION

Model Labor Op. Labor Time ------------------ --------- ----------- Pickup (Regular Cab) T7331 3.1 hrs. Pickup (Ext. Cab) T7332 3.7 hrs. Two-Door Utility T7333 4.4 hrs.

For vehicles repaired under warranty use:

#### Note: Labor operation is coded to base vehicle coverage codes in the Warranty System.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.