Automotive camshaft abnormal sound phenomenon:

1. Engine idling sound of a slight but clear, when heavy and slow rhythmic "blah" sound, the apparent speed of sound when, at high speed sound vague and unclear.

2 engine speed from the Camshaft  side of the cylinder re-issued blunt sound, the sound of high speed turbid.

3-cylinder sound test fire off the same.

4. Camshaft bearings near the vibration.

Reasons:

1) make the engine sound of the strongest state in the run, hit with a screwdriver in the cylinder at the vicinity of the bearing parts of auscultation, if somewhere in sound blunt and is accompanied by vibration, for the Camshaft  bearings made of the section ring.

2) to test the sound off the fire did not change, slow change throttle, if the idle sound clear, clear sound when in speed, high speed from the messy sound weak, for the automotive camshaft bearing axial clearance is too large or loose.