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 UNITS 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 correct pulley fastening.
3	CHECK ON TIMING CHAIN TENSION	All OK	Problems encountered	Operation
	Check that the chain tension is not excessive	Move on to Step 4	Excessive chain tension	Restore the correct timing chain tension.
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 tensionerOp. 1032C18 TIMING BELT MOVING TENSIONER - R.R.
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 WATER PUMP - R + R