For 1990-2009 cars

# EXHAUST MANIFOLD / NEW DESIGN TO CORRECT EXHAUST NOISE

SOME 1980-1981 DEVILLES AND BROUGHAMS AND 1980-1983 LIMOUSINES AND COMMERCIAL CHASSIS' EQUIPPED WITH A 6.0L V-8 ENGINE MAY EXPERIENCE AN EXHAUST NOISE BY THE LEFT EXHAUST MANIFOLD AREA. A NEW LEFT EXHAUST MANIFOLD (P/N 1628232) HAS BEEN RELEASED FOR SERVICING VEHICLES WITH THIS CONDITION. TO REPLACE THIS EXHAUST MANIFOLD, PROCEED AS FOLLOWS, PAYING PARTICULAR ATTENTION TO THAT PART OF THE PROCEDURE WHICH IS SHADED. REMOVAL: 1. REMOVE AIR CLEANER AND TUBE ASSEMBLY FROM AIR PREHEAT STOVE. 2. REMOVE SCREWS SECURING AIR PREHEAT STOVE TO EXHAUST MANIFOLD AND REMOVE STOVE. 3. DISCONNECT EXHAUST PIPE FROM MANIFOLD. 4. REMOVE OXYGEN SENSOR. 5. IF EQUIPPED WITH LOCKING TABS, BEND LOCK TABS FROM BOLT HEADS. 6. REMOVE BOLTS AND MANIFOLD. INSTALLATION: 1. LUBRICATE CYLINDER HEAD MOUNTING SURFACES WITH A THIN COAT OF A MOLY-BASED LUBRICANT (GRAPHITE). 2. IF EQUIPPED WITH LOCKING TABS AND BOLTS, DISCARD THESE PARTS AND INSTALL MANIFOLD WITH PREVAILING TORQUE BOLTS (P/N 1622236) AND TORQUE TO 25 N.M (19 FT.LBS.). 3. INSTALL OXYGEN SENSOR. 4. CONNECT EXHAUST PIPE TO MANIFOLD. 5. INSTALL SCREWS SECURING AIR PREHEAT STOVE TO EXHAUST MANIFOLD. 6. INSTALL AIR CLEANER AND TUBE ASSEMBLY TO AIR PREHEAT STOVE. FOR WARRANTY PURPOSES, USE OPERATION NUMBER J0101 AT 1.0 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.