EXHAUST MANIFOLD LEAKS NEW MANIFOLD TO REPAIR P/N

EXHAUST MANIFOLD LEAKS

VEHICLES AFFECTED: 1981-86 C/K TRUCKS, P CHASSIS AND MOTORHOME CHASSIS WITH 7.4L (VIN CODE W) ENGINES AND CAST IRON EXHAUST MANIFOLDS

Some 1981-86 trucks with 7.4L engines and cast iron exhaust manifold may experience a condition where an exhaust leak develops between the manifold and the cylinder head mating surface causing a noise condition.

Starting in 1987, an improved cast exhaust manifold using nodular iron instead of grey iron was released on the 1987 R/V trucks with the 7.4L engine. The nodular iron manifold is less susceptible to heat warpage than the previously used grey iron exhaust manifold. This manifold can be used to repair leaking exhaust manifolds on earlier year trucks and motorhomes. This manifold is NOT interchangeable with tubular manifolds used with the H5D (Federal Emissions NA5/NA6 equipped trucks built after January 1, 1985, Heavy Duty Emissions and dual air pumps) emission system. To install, the following parts are required:

Part No. Usage Quantity -------- ----- --------

14103191 Manifold-Exhaust LH 1 10045732 Manifold Assembly-Exhaust RH 1 14053573 Stud-Exhaust Manifold LH 3 14053574 Stud-Exhaust Manifold RH 3 587575 Spring-Exhaust Manifold 6 9422297 Nut-Exhaust Manifold (3/8-16) 6 120395 Washer-Exhaust Manifold (3/8 Flat) 6 15592451 Seal Assembly-Exhaust Manifold 2 3909821 Bolt-Exhaust Manifold (3/8 x 1 3/16) 16 10017198 Plug-Oxygen Sensor (18mm) LH Side 1 5617102 Gasket-Oxygen Sensor Plug LH Side 1 10068600 Shield-Starter 1 9439915 Nut-Starter Shield (1/4-20) 2

NOTICE: THE RIGHT HAND MANIFOLD ASSEMBLY INCORPORATES A SHORTER HEAT STOVE. TO PROTECT STARTER WIRING, A HEAT SHIELD (P/N 10068600) MUST BE INSTALLED.

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.