'HOOT' OR 'MOAN' NOISE DURING STEADY THROTTLE

SUBJECT: "Hoot" or "Moan" Noise During Steady Throttle with Engine Speed Between 1800-1850 RPM (Install Additional Exhaust Clamps on Intermediate Exhaust Pipe)

MODELS AFFECTED: 1991-1997 Saturns

CONDITION: Some customers may comment about a "Hoot" or "Moan" noise from the exhaust with the engine speed between 1800-1850 RPM. The customer may comment that the noise is coming from the rear of the vehicle. This noise is present during a narrow RPM range and during balanced throttle or light throttle deceleration. The noise may be most noticeable in vehicles equipped with automatic transaxles at 64 - 81 km/h (40-50 mph) with TCC applied, and in vehicles equipped with manual transaxles in 3rd or 4th gear at 1800-1850 RPM. This noise can also be heard with the vehicle stopped in Neutral or Park and the engine speed between 1800-1850 RPM.

CAUSE: The noise is caused by exhaust system resonance.

CORRECTION: The installation of the additional exhaust clamps will add mass to the intermediate exhaust pipe and cause it to resonate at a frequency that is not audible to the customer. Refer to the following procedure for the correct placement of the additional exhaust clamps.

PROCEDURE

1. Raise vehicle.

2. Install two exhaust clamps on the straight section of the intermediate exhaust pipe forward of, and parallel to the front of the fuel tank, 100 mm (4 in.) from the outboard bend of the intermediate exhaust pipe as shown in illustration.

3. Align the exhaust clamps as shown in illustration.

4. Lower vehicle.

5. Verify customer's concern has been repaired.

PARTS REQUIREMENTS: 25517280 Clamp-Exh Muff (2-Required)

CLAIM INFORMATION: To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System as follows:

Labor Case Operation Type Description Code Time

VW Install Additional Exhaust T9766 0.3 hrs Clamps on Intermediate Exhaust Pipe

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.