312002009 - S012 CYCLICAL ENGINE BUZZING

There is a loud and constant noise coming from the engine area that occurs at constant intervals.

		Test results
1	AUXILIARY DRIVE BELT CHECK	All OK	Problems encountered	Operation
	Check whether the noise disappears if the belt is disconnected Do not let the engine run for long with the belt detached	Move on to Step 2	1. The whistling noise stops2. The whistling noise remains constant	1. Continue as instructed in the    See table S010 ENGINE WHILSTLING / SERVICES BELT NOISY2. Move on to Step 2
2	ALTERNATOR CHECK	All OK	Problems encountered	Operation
	Check the alternator and in particular the condition of the bearing the correct fastening of the pulley	Move on to Step 3	1. Alternator bearing damaged2. Incorrect pulley fastening	1. Replace the alternatorOp. 5530A10 2. Restore the correct pulley fastening.
3	TIMING BELT TENSIONING CHECK	All OK	Problems encountered	Operation
	Check that the belt tensioning is not excessive	Move on to Step 4	Excessive belt tensioning	Restore the correct timing belt tensioning.
4	TIMING BELT TENSIONER CHECK	All OK	Problems encountered	Operation
	Check the belt tensioners and in particular the condition of the corresponding bearings.	Move on to Step 5	Moving tensioner bearing damaged	Replace the moving tensioner    Op. 1032C10 TIMING SYSTEM MOVING TENSIONER - R.R WITH TIMING BELT/CHAIN REMOVED
5	WATER PUMP CHECK	All OK	Problems encountered	Operation
	Check the water pump and in particular the condition of the bearing	End of diagnosis	Water pump bearing damaged	Replace the water pumpOp. 1088C10