Thump at Quick Accelleration from Stop

[crwarren11]

Hi guys,

I have a 2000 Boxster Tiptronic with almost 97k miles.  Over the past few weeks a "thump" has developed when I accelerate quickly from a stop (sitting at a stop light or stop sign).  It feels like it is inertia related, like something is moving back, when I punch it.  I feel the thump, don't really hear anything.  If I do fast start in 2nd gear, I still feel a thump, but it is much less.  If I accelerate at an average rate then it doesn't happen in either 1st or 2nd.  At first I thought it was maybe a slip in the transmission, but since then it really feels more like something is actually moving to create the thump.

 

Car is running great otherwise, no CELs, no leaks, normal temps, etc.  I did rebuild the transmission in Oct 2013 and have almost 5k miles on it since then so I am probably overly sensitive to things that seem to be transmission-related.

 

Please let me know if this sounds familiar to any of you and what I can look for in diagnosing the problem.

 

Thanks!

 

[Ahsai]

Engine mount?

[JFP in PA]

Engine mount?

 

+1.  A common complaint, and an easy fix.

[crwarren11]

Ok great, thanks!  I actually have a new one already, been sitting here for months looking for the time to put it in, but my wife's smoking X5 took priority.

[crwarren11]

That was it. Switched it out today and it feels like new. No thump, less vibration, smoother shifting. Took me a few hours and had to take the carrier to a shop to press out the old and in the new, but well worth the $25! Thanks for the advice!

[Ahsai]

:thumbup:

[crwarren11]

I have a question about the "stop" p/n 986-375-255-01.  When I removed the carrier/mount assembly, there was only one of them on mine on the "nuts" side of the bracket:

There wasn't one on the "bolts" side:

The parts diagram shows one on each side (#3 in the diagram), but as you can see above there was definitely only one on mine.  Should I have two?  Should I add another one?

My mount was completely shot...the guts literally fell right out when I took out the bolts...

http://vid779.photobucket.com/albums/yy73/crwarren11/Porsche/IMG_3314.mp4