I have kept the engine filled on my 04 with 15W50 since the first oil change and this car sits months at a time. NEVER has the engine made the noise you guys are talking about.

 

I can easily email you the sound file so you can hear it yourself... PM me your email and I'll send it over...

-Blake

 

Your car has a wet sump motor. Again, it is totally "normal".

 

1999Porsche911 - I was under the impression that you have an 04 GT3. Is this correct?

-B

 

Yup. I listened to the sound file you sent. Hard to determine much except I can hear a rattle/knocking in the background. That is a sound I have never heard on my car even when it has sat for 3 months without being started. The noise also goes on so long that it would be a concern for me and I would request that Porsche take a look and provide me with an a written official position as to what the noise is and a statment that it is there by design.

Curious as to why a Porsche mechanic would even investigate the noise, if as some here have stated, it is "normal".

 

Some of these cars have been experiencing loose intermediate shaft gears and that sounds like rattling chains/tensioners.

 

0W-40 Mobil 1. My 2001 996TT made the same sound on cold startups.

 

I can feel a vibration in the clutch pedal as the GT3 does the rattle sound on cold start up (not driven for days). It only makes the sound for a very few seconds. Use factory recommended 0W-40 Mobil 1.

 

As you described it as a rattle and not a tick or knock, I’d put my money on a CAT. I had this sound appear twice in one year. Both CATs. Both replaced under warranty. my car is an 04 996 C2 with 60k miles. All is well. Too much track time I guess. I hear its not uncommon for the 996 series when used lots on track or ran at high rpm often.

All the best...

 

dont start the motor.
open the door
and slam it shut.
if you hear rattle from the *** end, your cat is gone.
no, this is not a joke. it is how i found out my cats are dead.
this test worked on all my 996.

 

Talk about bringing a thread back from the dead. 4+ years and no problems related to the start up rattle. Its still normal AFAIK...

 

Cool Sloth - and search really works!

Thanks to all of you Rennlisters for the great feedback. I've got my first DE day in a few weeks and just got the BendPak scissor lift up and running at the track garage... Can't wait to lay down some rubber!

-Blake