If you encounter a customer complaint that there is an unusual sound heard at 1,200 rpm, best described as a fluttering sound which can be duplicated in Park or Neutral and while moving at low speeds, it may be caused by the timing belt.
The sound is a resonance from the timing belt created during normal engine operation and transmitted from the engine to the body where it becomes audible in the passenger compartment. The condition is non-detrimental and will not impact vehicle use or long term durability. It may vary slightly in volume from vehicle to vehicle due to the stack up of small variations in manufacturing tolerances.
If you have a vehicle with an unusual, noticeable or distinctive sound of this type when compared to comparable vehicles, a countermeasure belt idler and timing belt tensioner bracket may be installed along with adjusting the front engine mount to reduce the presence and transmission of the sound.
This applies to 2011 and early production and 2012 Subaru Legacy/Outback equipped with the 2.5L engine. Changes were made in production mid-December 2011.
The repair involves replacement of the timing belt tensioner bracket (#7) and idler (#10), and adjusting the engine mount.
TIMING BELT TENSIONER BRACKET
Note that the diameter of the bolt holes in the bracket have been enlarged which permits a slight adjustment of the bracket. This allows achieving additional extension of the automatic belt tension adjuster rod.
Install the C/M timing belt tensioner bracket using the three bolts that were removed. Just snug the bolts, allowing slight movement for positioning.
Lift up the bracket. Then rotate the bracket clockwise and torque the bolts to 18.1 ft.-lbs. Install the C/M belt idler and the remaining components in reverse order of disassembly.
MOTOR MOUNT ADJUSTMENT
An engine hoist and chain will be needed to support the engine. Loosen the right rear and left rear motor mount nuts (do not remove either nut). Loosen the front motor mount nut and bolt and remove the nut, leaving the bolt in place.
Raise the engine slightly until the bolt can be moved in and out of the mount with no resistance (free movement). Install the front motor mount nut and tighten to 33.2 ft.-lbs. Lower the engine and torque the rear motor mount nuts to 33.2 ft.-lbs.