Knocking sound coming from left (drive side) rear area

[Rui725]

Being a tiptronic car, It's hard to tell whether the 2nd gear is rough to engage, but, as a general rule, the car chooses 2nd gear when coming off from a stopped position in normal every day driving. From a range of 1-5, 1 being the worse, 5 being the optimal, i would say there it's a 3.25 with a bit gear slippage when the computer engages the 2nd gear off a stop. There is a small lag that causes a very slight stutter in the car when engaging 2nd off from neutral.

I reckoned it could be the mount, but upon acceleration, there is no strange vibration. Instead, the car feels better at higher rpm's and speeds. I do not have a record of whether the engine mount has been changed or not, but most likely it is still the original engine mount. I do feel there's a lot of movement on the top engine compartment right behind my head when hitting pot holes and uneven roads though.

Is there a way to check for worn engine mount when up on a lift? From what I've read the bona fide sign of a need for a new engine mount is strong vibration at 4k rpm, which I have yet to experience. I'm going to have to check the wheel bearings when I have access to a lift and a 2nd hand to help me out. One thing I learned about owning a Porsche is preventative maintenance and reading goes a long way, and most of this I have to give credit to the helpful online community.

[JoeFromPA]

Completely missed tht you have a tiptronic - disregard my comment on shifting quality.

Here's the thing - a boxer six is inherently balanced but will still be rougher at lower speeds. Even with a broken engine mount, you should experience less vibration at medium high engine speeds - what you might get is harmonic resonance at certain speeds.

Anyway, I can't comment on the stuff behind your head, except to say that it's easy to access those things and check to see if they are on tight. IIRC, they are all tightened in back there by hand/latch. So if something is moving around, it probably became unlatched somehow. None of that shelf should move if it's latched properly, at least as it is on my car...

You can not truly inspect the engine mount until it's out of the car. Even from under the car, its true condition is hid behind some rubber buffers.

If your car's is the original, I'm betting 95% its shot. That being said, just because it's shot doesn't mean it's the cause of your clunk.

Other symptoms of a bad engine mount = feeling the engine move behind you (front to back & some twisting), watching tha tailpipe move a good amoutn when the car takes off pretty quickly from a full stop, and various vibrations and resonances.

It's basically a rubber ball around a metal support that holds your engine supported and stable, and the rubber rips and tears. I just started a thread this morning about my own recent replacement of the mount - you can see it in there and how ripped my 99 boxster's was.

[dennis]

I have the same thing going on and cannot figure it out. It seemed to happen right after I did some exhaust work, so I am thinking when the engine torques, it may hit a pipe? Did yo do any exhaust work recently?