NEW DESIGN CRANKSHAFT PULLEY. GMC Truck GMC P RV/Van/Commercial Chassis 1986

VEHICLES AFFECTED: 1986 C, K, G, P 10/1500 - 30/3500 EQUIPPED WITH THE 4.3L (VIN CODE N) 5.0L (VIN CODE F, H) 5.7L (VIN CODE L, M, K)

Some 1986 C, K, G, P model trucks equipped with the 4.3L, 5.0L and 5.7L engines without air conditioning (A/C) may experience belt squeal or popping noise from the crankshaft pulley area. These noises may be caused by a separation in the generator belt groove portion of the pulley.

If this condition is encountered, it can be repaired by replacing the pulley with a new design pulley. These pulleys were changed in production effective with the following VIN breakpoints:

Model Plant VIN Breakpoint ----- ----- -------------- C/K Flint - Line 1 GMC 729913 Chevrolet 426588 Line 2 GMC 528408 Chevrolet 192683

St. Louis GMC 530639 Chevrolet 119883 Janesville GMC 511469 Chevrolet 128233

G Van Lordstown GMC 518113 Chevrolet 118449 Scarborough GMC 525644 Chevrolet 163060

P Chassis Detroit Assembly GMC 503976 Chevrolet 330510

Parts Information

New Part Number Description Application Quantity ----- ----------- ----------- -------- 10069912 Pulley C/K 1,2,3 4.3L (N) 1 w/o A/C C/K 1,2,3 5.0L (F,H) 1 5.7L (L,M) w/o A/C

P 2,3 5.7L (M,K) 1 w/o BM3, w/o A/C

10069913 Pulley G 1,2 4.3L (N) 1 w/o A/C, VO5 G 3 (03-05-06) 4.3L (N) 1 w/o A/C, VO5 G 1,2 5.0L (F,H) 5.7L 1 (L) w/o A/C, V05 G 3 5.7L (L,M) 1 w/o A/C, VO5

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.