POPPING NOISE IN FRONT FLOOR PAN AREA ON ACCEL AND/OR DECEL

MODELS AFFECTED: 1989-1990 DE VILLES AND FLEETWOODS

Some 1989-1990 DeVilles and Fleetwoods may have a popping noise when accelerating, coasting, or braking (i.e., any time) which seems to come from the front floor pan area. This may be due to broken spot welds at the #2 frame mount reinforcement plate on the floor pan and excess clearance of the #2 or #3 lower cushions to the frame on the right or left side.

To repair this condition raise the car on a hoist and support the frame. Refer to Figure 1.

1. Remove the #2 and #3 mount bolts and check for broken spot welds at the #2 frame mount reinforcement plate on the floor pan. Identify any #2 or #3 lower cushions which have excess clearance to the frame by looking for signs of relative motion, such as shiny areas on the frame around the mount.

2. MIG weld any broken welds and prime the repair area with zinc-rich primer and then color coat.

3. Elongate lower cushions you suspect to be loose by squeezing them on their flats in a vise so relative motion between the cushion and the frame in the fore/aft direction is eliminated.

NOTE: The lower cushions are normally a press fit in the frame.

4. Lube upper and lower cushions and bolts with petroleum jelly before reinstalling and torquing to 100 N-m (72 lbs. ft.).

NOTE: The upper cushions on the #2 mounts were eliminated during the 1989 model year. If they are present, however, reinstall them.

For warranty purposes use Labor Operation T6463 at .8 hour.

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.