EXHAUST MANIFOLD LEAKS NEW MANIFOLD TO REPAIR P/N

Model and Year: 1981-86 C/K TRUCKS, P CHASSIS AND MOTORHOME CHASSIS EQUIPPED WITH 7.4L (VIN W) ENGINES AND CAST IRON EXHAUST MANIFOLDS

Chevrolet Dealer Service Bulletin 86-255-6F, dated November, 1987, is being revised to correct the labor operation number for the right side repair. All copies of 86-255-6F dated November, 1987 should be discarded.

Some 1981-86 trucks with 7.4L engines and cast iron exhaust manifolds 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, with 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- 1 Exhaust RH

14053573 Stud-Exhaust 3 Manifold LH

14053574 Stud-Exhaust 3 Manifold RH

587575 Spring-Exhaust Manifold 6

9422297 Nut-Exhaust Manifold 6 (3/8-16)

120395 Washer-Exhaust Manifold 6 (3/8 Flat)

15592451 Seal Assembly - 2 Exhaust Manifold

3909821 Bolt-Exhaust Manifold 16 (3/8 x 1-3/16)

10017198 Plug-Oxygen Sensor (18mm) 1 LH Side

5617102 Gasket-Oxygen Sensor 1 Plug LH Side

10068600 Shield-Starter 1

9439915 Nut-Starter Shield 2 (1/4-20)

NOTICE:

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

Labor Times and Operation Numbers:

Exhaust Manifold Replace

J0100 - Right Side C/K 1.6 hrs. J0101 - Left Side C/K 1.4 hrs.

Add for A/C .4 hr - Left Side

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.