Exhaust Moan Or Vibration Supplement To 02-06-05-003G - keywords pipe resonance
| Subject: | Exhaust Moan or Vibration Supplement to 02-06-05-003G |
| Models: | 1999-2008 Chevrolet Silverado, Silverado Classic Reg. Cab Short Bed |
| 1999-2008 GMC Sierra, Sierra Classic Reg. Cab Short Bed |
| with 4.3L Engine (VINs W, X - RPOs L35, LU3) |
This PI was superseded to update models and model years. Please discard PIT3566B.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some owners may comment of a moan or vibration at low vehicle speeds between 900-1200 RPM under load. This is the same condition that is described in Bulletin 02-06-05-003G (or later). However, the bulletin does not cover regular cab vehicles with a short box. This information may be helpful in addressing this condition on these vehicles that are not covered by the bulletin.
Recommendation/Instructions:
The flex coupling listed in Bulletin 02-06-05-003G (or later) will not fit on these trucks because there is not a sufficient length of straight pipe in this area to accommodate the coupling.
Obtain a 3 inch weld in flex coupling locally; most larger exhaust shops will have these available. Install the shorter flex coupling in the same location described by the bulletin by cutting the exhaust pipe to accommodate the flex coupling and welding it in place.
If this does not completely eliminate the moan/vibration, it may also be necessary to install one or more damper weights P/N 10199232 to the exhaust pipe in the area above the rear axle.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
