I have a 1997 Accord and I have noticed recently that if I accelerate to over 3000 RPM and then let go of the gas pedal, about a half second later I will hear a thump/thud from the rear. I took it in to my mechanic and he looked at it and said there was nothing to fix. He said the transmission is just getting old, and that down the road I'd have to either replace the transmission or get a new car. Then when I went to pick up the car, I asked him how much longer the transmission would last, and he changed his mind and said the car was fine and I wouldn't have to replace the transmission in the future.

What do you guys think? Is the thump/thud normal for a car this old, and I don't have to worry about any problems related to it down the road?

 

Do you have a video of if while driving. It came be many things.

 

If it's from the rear of the car, I'd think exhaust moving and thumping/thudding against the floor.
Another possibility would be the sway bar thumping/thudding due to a broken sway bar link.

 

Sorry it took so long to reply. I finally put up a video - you can hear the noise at the very end:

https://www.youtube.com/watch?v=c10hNYdZmoA&feature=youtu.be

My mechanic did replace the muffler a couple months ago, and I'll have to check but I'm pretty sure I got the sway bar link replaced a year ago.

 

That sound is hard to tell. Do you know if you went over something when it sounded. I would have the mounts looked at (engine/trans). It seems to me as soon as you left off the thump sounds (less power being transferred causing the thump from the mount). That's what my guess would be but not being there I couldn't make a definitive diagnosis.