CJFusco

Hey all -- I had a nerve-wracking night last night: after I finished an oil change on my 07 987 CS, I was letting the car idle in the garage to check for leaks, and noticed an intermittent and irregular tapping/knocking/rattling noise that seemed to be independent of engine RPM. The way I would describe it is like how when you have a pair of jeans in the drier and the metal zipper or button sometimes claps against the side of the drier.

When you start the car, you don't hear the sound immediately -- it takes about 30-45 seconds to start. It seems to go away once the engine is at operating temperature. You don't hear it at all when the car is being driven: everything sounds and feels normal.

At first, I assumed cause-and-effect: the oil change had something to do with the noise. I'm not sure why or how that would be the case, but I noticed no noise until I changed the oil, so I feared the worst. But then I noticed something interesting (and relieving!): the noise goes away when I push in the clutch pedal!

My new theory is that the noise has been present for some time, but I never noticed it until the oil change because I don't frequently let the car idle in the garage: I start it, put it in gear, and drive it, following the normal warm-up procedure.

A quick search points to a clutch release bearing being the culprit, but I wanted to get your input. What do you think might be going on here? Thanks in advance.

extanker

just a short list
cut open your old filter and look for metal/hard plastic bits
are you SURE the new filter did not get twisted
get a professional ear on it
throw-out bearings usually make most of their noise when stepped on
and yes that it may have just started after an oil change sure points to cause and effect BUT stepping on the clutch quiets it confuses diagnostics
i would cut back on using it a tad until i found out waazz sup

CJFusco

Thanks for the reply. I think I meant the clutch release bearing (?) and not the throw-out bearing. But the fact that the noise doesn't recur when I depress the clutch would suggest that it has something to do with the clutch/transmission, and not the engine, yes?

I am already planning on sending out the old oil to Blackstone for diagnostics (was planning on it even before hearing this noise), but I'll also check the paper filter. I also have a magnetic drain plug, and it didn't have any metal on it when I removed it last night.

To further confuse things, during this oil change I also switched to LN Engineering's twist-on filter and switched from Mobil1 to Gibbs Driven DT40. I didn't bring it up in the OP because I didn't want this thread to turn into a "which oil is better" debate.

extanker

clutch release bearing and throw-out bearing are one and the same . The oem filter can twist and impede oil flow but that now is not an issue . ya need to get a pro ear on it imho

TexasRider

As above as tanker said ^^ is my first guess too.