Info - Serpentine Belt Identification and Diagnosis
| Subject: | Serpentine Belt Identification and Diagnosis |
| Models: | 2001-2003 Chevrolet Silverado |
| 2001-2003 GMC Sierra |
| 2003 Chevrolet C4500/5500 Medium Duty Truck |
| 2003 GMC C4500/5500 Medium Duty Truck |
| with 6.6L Duramax™ Diesel Engine (VIN 1 -- RPO LB7) |
This bulletin is being revised to add additional models and model years. Please discard Corporate Bulletin Number 02-06-01-010 (Section 06 -- Engine).
The following tables will assist the dealer in selecting the correct belt to install based on the engine configuration.
Generator | EGR Vacuum pump | RPO Code | Broadcast Code (BCC) | Part Number | Belt Length |
|---|---|---|---|---|---|
105 A | N/A | K68 | UUS | 97223129 | 2830 mm |
130A/150A | N/A | KG8 or 8A7 | UZA | 97223130 | 2853 mm |
Dual 105A | N/A | K65 or 8X5 | UUT | 97223131 | 3294 mm |
Generator | EGR Vacuum pump | RPO Code | Broadcast Code (BCC) | Part Number | Belt Length |
|---|---|---|---|---|---|
105 A | No | K68 and NF2 | UZZ | 97300653 | 2992 mm |
130A/150A | No | (KG8 or 8A7) and NF2 | WAA | 97300654 | 3012 mm |
Dual 105A | No | (K65 or 8X5) and NF2 | WAB | 97300655 | 3455 mm |
105 A | Yes | K68 and NC1 | WAA | 97300654 | 3012 mm |
130A/150A | Yes | (KG8 or 8A7) and NC1 | WAC | 97300656 | 3034 mm |
Dual 105A | Yes | (K65 or 8X5) and NC1 | WAD | 97300657 | 3476 mm |
Generator | EGR Vacuum pump | RPO Code | Broadcast Code (BCC) | Part Number | Belt Length |
|---|---|---|---|---|---|
105 A | N/A | K68 | WAA | 97300654 | 3012 mm |
130 A/150 A | N/A | KG4 | WAC | 97300656 | 3034 mm |
Dual 105 A | N/A | K65 | WAB | 97300655 | 3455 mm |
When looking at a belt, the part number, the broadcast code (BCC) and the belt spec-length are printed on the smooth side in white letters.
Diagnosis
The following information may assist the dealer with diagnosis of different belt conditions or failure modes.
Belt conditions may be generalized into two typical symptoms: shredding or belt wear, and noise. For shredding or wear conditions -- pulley alignment , a wrong idler pulley or foreign objects are the most found causes. Inspect all pulleys for proper alignment. Visually inspect that the belt is going according to the correct routing and that the correct pulleys are installed. Smooth pulleys should ride against the smooth side of the belt and ribbed pulleys should ride against the ribbed side of the belt.
The first issue with noise is a squeak at engine shutdown. This is a normal condition and no repairs should be made. Because of the higher cylinder pressures in a diesel engine, the engine stops faster than a gasoline powered engine. While the engine itself stops quickly, the other accessories have momentum. When the engine is shut down, the crankshaft stops and the accessories attempt to continue rotating. The squeak is produced when the belts slips slightly against the crankshaft pulley. If the squeak is produced while the engine is running, then look for contamination/debris on either the belt or the pulley. Also inspect the pulley system for misalignment.
Be sure when replacing a belt, especially for any noise concerns, that you select the correct part number from the charts above.
If the noise concern relates to either a knock or tension noise, inspect for the correct length belt. A belt that is too long could allow the belt tensioner to knock against its internal stop.
Some tensioner movement is normal and should not be the cause of concern. The tensioner will move back and forth as the tensioner attempts to remove slack from the serpentine belt.
