| Subject: | Rattle Noise In Engine (Install Timing Tensioner Kit) | 
| Models: | 1996-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado and P Models | 
| 1996-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma | 
| 1996-2001 Oldsmobile Bravada | 
| with 4.3L V6 Engine (VINs W, X -- RPOs L35, LF6, LU3) | 
This bulletin is being revised to add additional models. Please discard Corporate Bulletin Number 03-06-01-024B (Section 06 -- Engine/Propulsion System).
Some customers may comment on a rattle-type noise coming from the engine at approximately 1800 to 2200 RPMs.
The spark, rattle-type noise may be caused by torsional vibration of the balance shaft.
If detonation noise is present , perform detonation/spark knock diagnostics first.
Install a new tensioner assembly kit using the procedure below.
Tighten
Tighten the bolt to 25 N·m (18 lb ft).
Tighten
Tighten the bolts to 12 N·m (106 lb in).
Part Number  | Description  | Qty  | 
|---|---|---|
12458911  | Chain kit  | 1  | 
89017257  | Tensioner  | 1  | 
10220906  | Oil pan gasket  | 1  | 
88893989  | O ring and gasket kit  | 1  | 
3754587  | Water pump gasket  | 2  | 
89017259  | Cover  | 1  | 
For vehicles repaired under warranty, use:
Labor Operation  | Description  | Labor Time  | 
|---|---|---|
J1944  | Tensioner, Timing Chain - Install (S-10 Blazer, Pick Up, S-15 Jimmy, Sonoma With Manual Transmission)  | 8.6 hrs  | 
Tensioner, Timing Chain - Install (S-10 Blazer, Pick Up, S-15 Jimmy, Sonoma with Automatic Transmission)  | 9.0 hrs  | |
Tensioner, Timing Chain - Install (T-10 Blazer, Pick Up, T-15 Jimmy, Sonoma and Bravada)  | 7.5 hrs  | |
Tensioner, Timing Chain - Install (Express, Savana)  | 4.1 hrs  | |
Tensioner, Timing Chain - Install (Silverado, Sierra with Four Wheel Drive)  | 7.5 hrs  | |
Tensioner, Timing Chain - Install (Astro, Safari With All Wheel Drive)  | 7.5 hrs  | |
Tensioner, Timing Chain - Install (Astro, Safari)  | 3.9 hrs  | |
Tensioner, Timing Chain - Install (Silverado, Sierra)  | 3.9 hrs  | |
Add  | To Replace Crankshaft Gear  | 0.2 hr  | 
Add  | To Clean Parts On Vehicle over 48,280 km (30,000 mi)  | 0.1-0.3 hr  | 
Add  | With Skid Plate  | 0.2 hr  | 
Add  | With A/C  | 0.2 hr  |