Greetings board,

Im still trying to figure what this knocking sound is.

What I know is: 103,000mi. Car runs excellent.

At cold start, I dont hear anything. The noise starts in 3-5 minutes after a cold start.

I shorted each spark wire. No change.

I hear the noise mostly at idle, but I have heard the noise at warm start up, but then after driving I only hear it at idle.(mostly heard at idle)

Without the drive belts(a/c,ps,alt,)attached to the engine, I dont hear the noise.

With just the altenator belts attached, I dont hear the noise.

With just the a/c,ps belts attached, I dont hear the noise.

I want to conclude that this is an engine noise, but the lack of noise without the belts attached, makes me hesitate.

All comments, suggestions are welcome.

Thanks

Ps. When I raise the engine above idle the cadence increases, but eventually I can not hear it. Also the noise keeps lockstep cadence with spark for #1 cylinder.