WRINKLES, BLISTERS AND BUBBLES IN FABRIC ROOF COVER

The correction of wrinkles, blisters or bubbles in the cover material can be accomplished by either a shrinking process or by partially removing the cover in the affected area and repositioning to draw the wrinkle out of the material. The latter method would be required to correct the more serious cases of wrinkles, while the shrinking method would be the practical approach for less severe wrinkles as well as blisters and bubbles.

Shrinking can be performed in the following manner:

1. Pierce each wrinkle, blister or bubble with a small hypodermic needle and withdraw any trapped air from inside the wrinkle, blister or bubble. A hand held vacuum pump (Kent-Moore J-23738 or equivalent) attached to the hypo- dermic needle also can be used (Figure 1). When using either of these methods, place a piece of masking tape on material and pierce tape with needle. After evacuating trapped air, remove needle and rub clear silicone rubber sealant (Dow Corning 732-47 or equivalent) on tape at needle hole for sealing purposes. The masking tape provides location of needle hole and aids in sealer cleanup. Remove tape prior to heating operation.

2. Apply heat directly to the affected area with a heat gun.

NOTICE: Keep heat gun in motion when applying heat to roof cover material. Over-heating of vinyl will cause grain loss and permanent damage to the roof cover material.

When the material has warmed, it will begin to draw. At this point, the cover should be pressed against the roof panel. The heat will cause shrinking and reactivate the cement under the cover. The pressure on the top material will re-establish adhesion between the cover and the top.

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.