I have an '02 X with 43,000 miles on it. For some time now it has been making a knocking sound when I'm not in motion or in gear. I can only describe it as a diesel engine knocking. When the clutch is out the sound is extremely noticeable but when the clutch is pushed in the sound stops. This only happens after long periods of driving (usually about 30 minutes of constant driving). I've had the clutch kit replaced a few times already, both at roughly 42,000 miles, to try to alleviate the sound but it hasn't worked. Has anyone had or heard of this problem before?