I have the same problem going to rework the front end with new lower control arm ball joint and bushings-mounts and a pair of new struts which should correct the problem. Seems to be a common problem,.
Here ran across this Service Bulletin might shed some light. Sorry pics did not come through. I myself think it is more of a wear issue on the lower suspension components
TECHNICAL
Bulletin No.: 12-03-08-001
Date: August 06, 2012
Subject: Clunk or Thump Type Noise from Front Suspension
Models:
2008-2009 Buick Allure (Canada)
2008-2011 Buick Enclave, LaCrosse, Lucerne
2011-2012 Buick Regal
2005-2010 Chevrolet Cobalt (Including SS)
2006-2011 Chevrolet HHR (Including SS)
2008-2009 Chevrolet Uplander
2008-2011 Chevrolet Aveo
2008-2012 Chevrolet Equinox, Impala, Malibu
2009-2012 Chevrolet Traverse
2010-2012 Chevrolet Camaro
2011-2012 Chevrolet Cruze, Volt
2008-2012 GMC Acadia
2010-2012 GMC Terrain
2005-2006 Pontiac Pursuit (Canada)
2007-2010 Pontiac G5
2008 Pontiac Grand Prix
2008-2009 Pontiac Montana SV6, Torrent
2008-2010 Pontiac G3, G6, Vibe, Wave
Condition
Some customers may comment on a clunk or thump noise coming from the front suspension while driving over rough road surfaces. This noise will typically occur when the front suspension is returning to the upward position after a hard downward stroke, such as after driving through a large rut or pothole.
Cause
This condition may be caused by the jounce bumper slamming into the upper spring seat because it is not retained in the correct up position. The jounce bumper loses position due to oil being deposited onto its retention fingers. The oil is from the strut leaking.
Correction
Inspect the front strut(s) for evidence of oil. The leak may be slight but will still cause the concern. If oil is present, replace the affected strut, jounce bumper and dust boot (shield). Before reassembling the strut assembly, glue the new jounce bumper and new dust boot (shield) to the upper spring seat using the steps listed below. To further confirm this concern, the shield/bumper will easily slide up and down the strut shaft.
1. Clean the surface area of the upper spring seat using fine sandpaper.
2. Apply a light coat of *3M(TM) Automotive Adhesion Promoter, P/N 06396 or equivalent, to the top of the dust boot (shield) on the inside edge and to the top of the bumper. Allow to dry 10 minutes.
3. Glue the bumper to the inside of the dust boot (shield) as shown. Use *3M(TM) Duramix(TM) Super Fast Adhesive, P/N 04747 or equivalent. Allow to cure thoroughly 5-10 minutes at room temperature.
4. Apply a light coat of *3M(TM) Automotive Adhesion Promoter, P/N 06396 or equivalent, to the top of the dust boot (shield) and to the upper spring seat surface. Allow to dry 10 minutes.
5. Glue the dust boot (shield) to the upper spring seat as shown using the above recommended adhesive. Allow to cure thoroughly.
*We believe this source and their products to be reliable. There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any such items which may be available from other sources.
Parts Information
For part numbers and usage of the strut, see Strut Kit in Group 07.345 of the appropriate Parts Catalog.
For part numbers and usage of the boot/shield, see Strut Boot/Shield in Group 07.371 of the appropriate Parts Catalog.
For part numbers and usage of the bumper, see Strut Bumper in Group 07.395 of the appropriate Parts Catalog.
