323001366 - S012 CYCLICAL ENGINE BUZZING

There is a loud and constant noise coming from the engine area that occurs at constant intervals.
TEST RESULTS
1AUXILIARY UNITS BELT CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check whether the noise disappears if the belt is disconnected
Move on to Step 21. The whistling noise stops2. The whistling noise remains constant1. Continue as instructed in the    See table S010 ENGINE WHILSTLING / SERVICES BELT NOISY2. Move on to Step 2
2ALTERNATOR CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check the alternator and in particular- the condition of the bearing- the correct fastening of the pulleyMove on to Step 31. Alternator bearing damaged2. Incorrect pulley fastening1. Replace the alternator    Op. 5530A10 ALTERNATOR - R+R 2. Restore correct pulley fastening    Op. 5530A30 ALTERNATOR PULLEY OR FAN - R+R WITH ALTERNATOR REMOVED
3TIMING BELT TENSIONING CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check that the belt tensioning is not excessiveMove on to Step 4Excessive belt tensioningRestore the correct timing belt tensioning.
4TIMING BELT TENSIONER CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check the belt tensioners and in particular the condition of the corresponding bearings.Move on to Step 51. Fixed belt tensioner bearing damaged2. Moving belt tensioner bearing damaged1. Replace the fixed belt tensioner.2. Replace the moving belt tensioner.
5WATER PUMP CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check the water pump and in particular the condition of the bearingEnd of diagnosisWater pump bearing damagedReplace the water pump    Op. 1088C10 WATER PUMP - R + R     Op. 1088C14 WATER PUMP - R + R WITH TIMING BELT(S) REMOVED