Noise from Engine?
 

I have a 2001 boxster. My wife noticed a noise coming from the Engine compartment. She said it sounded like a drill/constant thumping noise. I started the car and drive it around the block. Nothing.

The second time I tried it, I let the car sit and idle for about 5 minutes. Sure enough... noise/knocking coming for the engine. It sounds like the knocking sound of a loose shock tower, but the frequency of occurrence was more constant, and the car was standing still.

This does not seem to occur all of the time. It seems that something is loose and vibrating? Thoughts?

I have no definitive answer here, but perhaps I can be of some help.

Based on your description it could be lots of things. The good news is that it does it while parked in the driveway. Suggest you take off the engine cover, start up the engine, and when it starts making the noise look around to see if something is loose and vibrating. Hopefully something is coming loose and can be tightened up.

Good luck.

By the way, any additional information you can provide would be helpful in diagnosing the problem. Such as, It only does it when idling, never at speed, only when in neutral, stops when I push the clutch in, or whatever.

noise
 

one of the members here had a noise that ended up being a part of the shock mount. could be the same thing.

I finally gave up and took the car in for repair. The shop found that the front motor mount was broken and vibration from the engine was the cause of the noise.

I have heard that broken motor mounts are a common problem in these cars. I am glad you were able to get it fixed, without breaking the bank.