timing chain rattle? It's not common but it happens and means you have to eventually replace your timing chain before it snaps and nukes your engine.

 

 

When you say "don't press the clutch" you mean in neutral with the clutch disengaged? If so it's probably a worn out clutch that's going to be getting replaced soon, or someone replaced it with a lightweight flywheel and you're hearing chatter.

 

 

Howany miles are on the engine? If you're in the 125k range or so there's a pretty fair chance it's on the original clutch that's showing signs of age.

 

 

 

If you could find out what flywheel he used that would help, anything that's NOT a dual mass flywheel will chatter, the lighter the weight the more it chatters.

 

Maybe, maybe not. Depends on the previous owner(s). Currently at 168k on the original clutch. 2nd owner, original owner was an adult, lived near a freeway for his commute and apparently didn't beat on the car. I've maybe sidestepped the clutch off the line at around 1500-2000 rpm a handful of times in the 2+ years I've owned my car. May chirp the 1-2 shift once a month if that. Don't sit at the light with the clutch pushed in the whole time.

As far as the OP's issue, if the original clutch/flywheel were replaced, a lighter flywheel can chatter. Or possibly if original the throwout bearing is going bad.