This groaning sound can also be reproduced when in 3 rd gear. When I slow down there is no groaning sound. 'm concerned that this might be a beginning of a major problem. Is this engine related, or is it caused by the exhaust, transmission. I had a similar situation on a truck and the dealer installed weights on the exhaust to eliminate that noise.
When accelerating there is a groaning sound at 3200 rpm on 2008 Pontiac G6
by sutak in East Freetown, MA on June 25, 2009
ANSWER by Russ , June 26, 2009
If your noise is only limited to specific engine load conditions then it could very well be related to the exhaust system. It may be a good idea the road test your G6 with a technician from your local dealer to try and determine to cause of the noise. I don't fine any service bulletins for exhaust or engine noise on your G6 at this time.