As i posted before, I get a decent amount of light blue smoke on startup every day. Also I've been hearing a sort of intermittent metallic buzz under the car (1 second duration) and esp when the car decellerates under it's own power. At first the dealership mechanic thought it was something loose in the exhaust system that was vibrating under resonance. But he couldn't find a single thing wrong. so now, esp bcs of the smoke, he wants to boroscope the cylinders to see if anything looks bad and since it's under CPO for another 8 months I would be covered (I have to love their integrity...really first class folks over here in Switzerland). and I think he suggested it could be linked to the metallic buzz (my german is quite poor so maybe I misinterpreted).

Question: could anyone imagine something in the motor internals that would cause an externally audible intermittent metallic buzz sound? as per my previous post, most folks think it's normal for these cars to smoke a little upon startup, bcs of the small amt of oil that leaks pass the rings. But apparently my mechanic isn't so content with it (even though they don't get any cash from me. or is it that they get cash from the CPO program?).

 

Does the smoke come out of both sets of tail pipes or just one side? and which side?

 

Could be AOS, for the rattle I would check your heat shields around the muffler. I have a rattle right now on my right rear which I'm guessing is caused by this.

 

My '07 C2S just spent two days at the dealer with the techs (both very good) looking for a metallic, raspy, buzzing sound from 2400-3100 rpms, particularly on throttle lift. Could not identify it. However, with the chassis ears they ruled out anything internal in the engine (timing chain, valve train, connecting rods, etc.). Seemed to believe it too was in the muffler baffles or catalytic converter, since everything else was screwed down tight (heat shields, pipes, etc.). They were as baffled as I am. Mine was under CPO (expires this week), but they documented everything in the system in case it causes a problem (other than severe annoyance on my part) in the future. Wish I could find mine as well, but you're not alone. You might have them check your timing chain.

 

This metalic buzzing almost sounds like the issue my Indy found during the PPI of my C2S. Root cause turned out to be a broken tailpipe. BTW, it's very easy to remove the tailpipe and eliminate/determine if that is the cause.

 

Wow. your description really resonates for me (pardon the pun ). really sounds similar. Will keep everyone posted on what they find. They will keep it for 2 weeks as they are sending my wheels off to be repaired as per our sales agreement (they had curb rash when I bought it). so my mechanic said he will go over the entire car with a magnifying glass to solve it. I think it really bothers him personally that he can't fix it . Germans for you....

 

I think it's predominantly the left side. maybe even 100%. I've heard that is common but missed the explanation as to why left only...

 

Me also

 

Your pipes cross over so that should be bank 2 of the cylinders if left side = driver side. Cylinder #4 gets the least effective cooling and most likely to have over heating issues such as scolded cylinder lining. There's a very lengthy write-up by hartech.org re this... do a search on RL for it if you'd like some night time reading. GL and hopefully this is not the case but scoping the cylinder is the right way to eliminate this as a possibility. BTW, they'll need to remove your spark plugs to scope the cylinders so a good time to go ahead and have the plugs replaced if you have not done that recently. Let us know the outcome.

 

Many thanks for the info!!! I appreciate it. Will definitely update everyone on the scoping.

would you guys recommend general anesthesia or sedation?

 

Don Julio 1942, Woodfords Bourbon, or Absinthe depending on the outcome... still better than a blown engine if you catch an issue with a scolded cylinder liner early enough. Hopefully it's nothing. GL.

 

Sounds like your mechanic is determined to find the issue which is nice. I wouldn't lose sleep for now about it. Like you say, this isn't the first 911 to smoke on startup.
My pse had all sorts of buzzing and rattling, mostly decel and ranges listed above. There were a number of support tabs that were breaking - apparently the exhaust isn't over-engineered by Porsche. Anyways, a few welds later with some reinforcements and I don't hear a thing
So hopefully something similar in your case

 

you guys are great! thanks. And I'm ever so glad I got the CPO warranty when I bought it 4 months ago.

 

Smoke on startup is almost certainly the Air Oil Separator. I had mine replaced, but the failure of the AOS can also mean scored cylinders. It wasn't a couple of months later until I had the entire engine replaced after boroscope check under CPO. Definitely let your tech examine your cylinders asap.

 

RCC what did they determine? Any news yet?