Squealing noise when engine revs

[london285q]

My smart has suddenly started making a high pitched squealing noise when the engine revs, any ideas? Video attached so you can hear

[10:45PM]

Belt idler bearings or belt/belt tension are first guesses.

What year is it?.... Mhd?

No video here?

[london285q]

63 reg mhd, sorry struggling to upload video on this website. It when there are high revs, as you go up through the gears and go to 4th or 5th it goes off

[10:45PM]

Does it do it when: engine is cold, you've got all lights on and you blip the acc.?

[london285q]

It does it when cold and when warm. It is more noticeable when cold though

[10:45PM]

need to hear it , though it does 'sound' like belt tension or belt idler wheel screeching.

do the headlight check, slack belt will be more apparent with load on the alternator

[tolsen]

Stuck pig is first guess.

My thought too.