My car has been making this sound for awhile. This is from a cold start, even on a warm today (such as today). The sound clip is actually the second start (forgot to turn the microphone on the first time) the first time it does pretty much the same thing, except the louder/rougher part at the begining lasts much longer.

Subaru WRX 2002 Sedan, no mods, 40k miles. The audio lacks low end completely cause I recorded it from my laptop.

The guys at tire world either haven't heard it (I haven't been there when it's happened) or don't think it's anything (they keep telling me nothing sounds out of the ordinary) and even back when I took it to Heuberger at around 15k miles it was doing it a bit then and they said they didn't hear anything odd.

So basically, anyone have any idea what that noise is? It can get much worse (the longer it sits, the colder it is, etc.) It seems to *mostly* go away after the engine warms up nicely. It also occasionally idles at 2500rpm (instead of about 600rpm) (which doesn't seem to be directly linked to the sound cause the sound will occur whether it's idling normally or high)

(since I cannot post the mp3/zip here I will link you to the post I made elsewhere: http://www.highaltitudeimports.com/vbulletin/showthread.php?s=&threadid=13506)

all subaru engines have a knocking sound when cold-light sound of knocking-although you may have a bad cam belt tensioner that is going bad-weve been having problems with these.when this tensioner gets bad-you will be able to also here the timing belt hitting the plastic belt cover

Is there danger of the timing belt derailing itself because of this bad tensioner? I had my tensioner replaced and the sound came back 5 days later. I'm wondering if I should spend more money to get it done again or grin and bear it?