We first noticed the noise/knock(?) today (5/24) while on our way out of town. The noise is only present, sometimes, when the engine is warmed up and idling, and goes away when the engine is revved. At one point when the car was turned off, it made a squeal sound as the engine came to a stop. We turned the car back on and off again, but it did not squeal again, and since then we have not heard any more "knocking" from the engine. Other than just making the knocking sound, the car seemed to run/perform just fine. My car is a 2001 AP1 with 93,XXX miles.

I have a short video below of the knocking sound. (my apologies for the shaky cam)
[media]http://youtu.be/juNQtGcgopE[/media]

Any advice is greatly appreciated.

PS: If it matters, my S2000 has always had a deeper tone than any other S2000 we've heard. We own 2, and live at Deals Gap so we've been around a lot of them.

 

Sound like a sticking BELT tensioner (not to be confused with a TCT)

Put a 14mm wrench on it and see if it operates smoothly. You should be able to push it down smoothly, and it should return smoothly with a good spring force.

 

 

Thanks Bill. Just checked it, belt pulley tensioner seems to be working fine. Shot a little lube on it just to be sure.

The noise seemed to be coming from deep down in the motor, maybe even toward the back. Oil level was good, just did it a few times that one day and hasn't done it since.