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Robert, UK Qualified Car Technician
Category: Mercedes
Satisfied Customers: 4708
Experience:  Fully qualified / self employed garage technician in the UK
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I have an X reg S320 and the engine fan has developed a loud

Customer Question

I have an X reg S320 and the engine fan has developed a loud noise. The car runs fine, the engine does not overheat but is noisy. Thoughts?
Submitted: 4 years ago.
Category: Mercedes
Expert:  Robert replied 4 years ago.



Hopefully I can help..


Can you explain exactly/describe roughly what the noise sounds like?


Has this been a recent fault or one that progressively got worse?

Customer: replied 4 years ago.

It sounds like a loud whirring sound, like an electric motor or a very loud fan. it comes on a few minutes after I start the car and occasionally stops. When I brake it gets a little quieter and the pitch of the sound goes down. It has not gotten progressively worse, it just started one day.

Expert:  Robert replied 4 years ago.

Hi..there. thanks for getting back..


Ok to rule out certain areas you will need to check within the engine bay as to where exactly this noise seems to emit from as thats about the only way to actually trace this down effectively..first checks would be for the mentioned noise coming from the auxillary belt at the front of the engine.if the noise definatly comes from there then switch the engine off and check the condition off the belt to see if loose in anyway etc as well as the fan itself coming into contact with method to rule out or verfiy - would be to remove the belt and run the engine for short moment and see if the noise is still present..if its not and the noise has stopped .then you 'll need to go further and check for obvious problems with the inc fan motor bearing or fan bearing / ac pulley switch off and on to see if the noise changes and spin/check carefully by hand to feel for issues as well as all the rest of the pulleys run off this belt inc the alternator pulley clutch.It can be hard to define a certain noise over the net without hearing but as above to best way forward would be to trace this issue to a certain area on the engine itself.once youve done that then you should be in a better position as to what needs checked or replaced even..i do hope this helps