minor "thump" from rear of car when pulling away

[sluggo]

Hi all - In my 2013 3.8 Premium I've noticed a noise from somewhere in the rear of the car when pulling away from a dead stop. Just as the car starts forward I hear a very slight "tump", as though something in the trunk has fallen over. It's very faint, and no one else has commented on it, but it's there.

There's no rattle or other associated sounds and no vibration felt through the wheel or seat. I suspect either the suspension or the drive train, but I have no evidence for either. I looked all through the trunk and spare tire well and found no loose objects that could explain it.

I believe the noise has been there from the time I bought it new. It has 15k miles on it now.

Any ideas?

 

[Taxman]

Is the "noise" the same with or without passengers in back seat or a heavy load vs unloaded trunk?

 

[Retry]

I have noticed exactly what you describe in my 2012. It is very slight and has been there for the past 6 months or so. Haven't taken it in to be checked. It seems to be less frequent with a full tank of fuel. It sounds like the rear wheels roll over an expansion joint just as you begin to pull away from a stop. I can feel it in the car although it's slight. A passenger wouldn't notice it.

 

[sluggo]

Is the "noise" the same with or without passengers in back seat or a heavy load vs unloaded trunk?

I rarely have passengers, but I have had about 150 lbs in the trunk from time to time and it happens with a loaded trunk.

 

[sluggo]

It sounds like the rear wheels roll over an expansion joint just as you begin to pull away from a stop.

Great description, and glad to hear others have noticed it. I didn't recall hearing it when backing away, so I tried it some in reverse and didn't hear it over a half-dozen attempts.