Fiat Stilo JTD rotary knocking noise

[Slinky]

Any thoughts folks, 04 plate 1.9 JTD stilo making a relatively loud rotary sounding knock.

Increases in frequency with road speed, only apparent when not under load (no throttle or clutch depressed), no change in pitch or anything along those lines.

Knock can be stopped by either applying the brakes or applying power. No change in brake feel and no knocks back through the pedals..

Your thoughts would be appreciated..

Cheers..

slinky

[H2DaE]

could be the auxiliary pulley, common problem on the JTD engine and has similar symptoms