Underhood Whine or Rattle Type Noise (Replace Tensioner)

This bulletin is being revised to update the warranty information. Please discard Corporate Bulletin Number 04-06-01-016A (Section 06 - Engine/Propulsion System).

Some customers may comment on a whine type noise and/or a possible rattle noise on light acceleration coming from the engine. This noise may seem more pronounced at start up after an overnight soak.

The source of the noise may be the balance shaft chain and the tensioner interaction. There are 2 balance shafts in this engine that are driven by the crankshaft to keep the engine running smoothly. This noise does vary from vehicle to vehicle and does not cause any durability concerns; however, some customers may find it objectionable.

A new tensioner has been designed to eliminate this noise. The kit consists of an oil fed tensioner, longer tensioner bolts, balance shaft drive chain and right side balance shaft assembly. Please note that it is necessary to install the updated balance shaft assembly because it contains an oil feed passage for the oil fed tensioner.

This new tensioner was introduced into production in the mid December time frame. If you have a vehicle built prior to VIN breakpoints 48123220 (Chevrolet) and 48123225 (GMC), install a new tensioner, P/N 89017543.

Follow the removal and installation instructions in SI for the Balance Shaft Chain Tensioner Replacement in the Engine Mechanical sub-section. You will also need to order and install a new rear oil seal, P/N 12568124.

For vehicles repaired under warranty, use: