[mcranners]

Need some help in diagnosing this sound,

any ideas, its a very faint but louder in person high pitch sound (Rubbing finger around the rim of a wine glass) when increasing and decreasing revs, you cannot hear it outside at all so dont think its the engine.

 

[thick]

could be a dodgy alternator mate try and get someone to listen in the engine bay when you rev it or use a long screwdriver to listen to the engine

 

[toffo123]

Yep. Disconnect the belt and start the car. If the noise goes, hey presto....job done.

 

[AJ]

Do you have an amp installed or have the headunit on when this is happening?
Does it get louder or anything when you rev harder?