RINGING NOISE AT 42 TO 45 MPH HEAT SHIELD VIBRATES

VEHICLES AFFECTED: 1985-86 'N' Series With 3.OL Engine

Some 1985-86 'N' models built between January and September of 1985 may exhibit an audible 'ringing' noise from the speed sensor heat shield located on top of the transaxle. This noise is dependent on engine speed, and it is most audible at vehicle speeds of 67 to 72 kph (42 to 45 mph). This corresponds to 1,650 to 1,800 engine rpm with transaxle in 3rd gear and TCC on.

The cause of this condition is the speed sensor heat shield vibrating against the transaxle case. See Figure.

Service Procedure

Raise the car up on the hoist and looking from the underside of the transaxle, bend the speed sensor heat shield away from the transaxle case until the distance between the heat shield and the transaxle case is 5 mm (3/16 in.). See Figure. After the heat shield has been bent away from the case, it should be visually checked to make sure the heat shield will not be contacting the exhaust manifold.

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.