By Tom Purser, ALLDATA editor, and Jeff Webster, ALLDATA technical writer

Some GM truck, SUV and minivan owners may complain about a rattle-type noise coming from the engine area at approximately 1,800 to 2,200 rpm. The rattle-type noise may be caused by torsional vibration of the balance shaft.

Figure 1

To fix the problem, follow the service procedure below for installing a new tensioner assembly kit. If detonation noise is present, perform detonation/spark knock diagnostic testing first.

Applicable Models: 1996-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado and P Models; 1996-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma; and 1996-2001 Oldsmobile Bravada (with 4.3L V6 Engine)

PARTS INFORMATION

Part Number   Description
12458911     Chain Kit
89017257    Tensioner
10220906    Oil Pan Gasket
88893989     O-Ring and Gasket Kit
3754587      Water Pump Gasket (2)
89017259    Cover

Figure 2

Service Procedure
1. Remove the engine front cover.