99 323i Drivetrain noise

[peoples1234]

I attempted to search, but was unsuccessful with finding a solution to my problem. For the record I am a BMW newbie. I recently purchased a 99 323i and I have what I would consider an abnormal thunk in the rear of the car occasionally when I take off or shift to second. I can slightly hear it going in to third. I was wondering if this was a normal noise that just develops with mileage. I, however, was thinking that it almost sounds like a broken transmission mount or even motor mount. Either way my question is does this sound normal or should I have it checked out. Other than that the car drives perfectly.

 

[MasterofPuppets]

Yes, you should definately get it checked out. You are not going to like this, but I have seen several 323i's tear the rear subframe right out of the floor which causes a clunk. Usually the left rear mount where the subframe bolts to the floor rips right out of the trunk area. I am not saying that is what happened to yours, it could be a simple transmission crossmember mount failure.

Just make sure you check the subframe mounts while you are under there. It could also be a diff problem, but again, worst case senario.

 

[geneo]

i have seen that also from pulling hole shots and i have seen the rear diff cover bolts become loose and clunk because there is a mount on it

 

[aNoodle]

The 1999 328 makes a slight clunk in the rear differential. This is normal and has been the same since I've had my car. Since I'm not sure what your clunk is, it would be hard to say it's the same as my normal clunk.