VivaJ73

2004 E320 4-matic (M112 E32 engine) - 120K miles

I am getting some whining / pitching / whirring noise from my engine.
It sounds somewhat like a supercharger (which my car doesn't have).

I ran the engine with and without belt to identify if it is coming from any of the components connecting to the belt.
Procedure:
- Take the belt of the evening before and check for any issues in the pulleys.
- Next morning (when the engine is cold), run the engine (should be ok for 1 or 2 minutes) and listen/record. Warnings lights will flash on but will go away when the belt is back on.
- Put the belt back and listen/record again.

I cannot note any big difference.
The tightener pulley on the water pump makes a grinding and rattling noise when spinning without belt. There is no play but probably a broken bearing. Will replace it.
Breather hoses / air intake?
Some of my breather hoses are a bit cracked where they connect to the valve covers. They are still on tight.
I ordered new parts anyway to replace them.
Parts: 140, 146, 152, 158, 170 and 3x 146
https://mb-teilekatalog.info/view_Su...=14&subgrp=030
Could the sound come from a leak in the air hoses?

I cannot find the noise on the engine with a stethoscope.
I replaced all the valve cover gaskets, so they should not be leaking air.

Anyone any idea what to look for?
And any thoughts on the water pump?
I will update after having installed the new breather hoses.