At idle the sound clear, clear sound speed when high speed when the sound becomes weakened by the clutter that disappear, can be identified as the camshaft ring.

1) make the engine run at the sound of the strongest state, hit with a screwdriver near the site of the cylinder at each bearing auscultation, if somewhere the sound blunt and accompanied by vibration, for the cam the hair shaft section bearing ring.

2) test the sound off the fire did not change, the slow transformation throttle, if the idle sound clear, distinct sound speed when high speed when the sound from the clutter becomes weak, compared with the camshaft bearing axial clearance is too large or loose.