Weird engine noise or fanbelt noise?

[Bertyt5]

The van has done this twice in 15mins of driving around town and disappears when you slightly rev the engine and doesn't come back
Any input please

Issues van has that may be connected?
My EGR needs replacing as I have p401 engine code
Fanbelt tensioner needs replacing

Link to video

Engine squeel

 

[Dellmassive]

Can you do a longer clip,,,,,,,
?.

Thought I heard a tensioner squeeling.

And dmf rattle.

And some kind of vacuum suck,pop?

 

[Bertyt5]

Can you do a longer clip,,,,,,,
?.

Thought I heard a tensioner squeeling.

And dmf rattle.

And some kind of vacuum suck,pop?

I wait for it to happen again as I can't replicate it..
If you watch the belt you see it move and engage something which I assume is the vacuum suck pop, I'm being lead down the alternator pulley is seizing up and needs doing

 

[DXX]

If you have a cig lighter to usb charger with a voltage display this will show the voltage increase on overrun and decrease on acceleration (blue motion smart alternator).
If the voltage is static when accelerating / overrun the alternator pulley clutch is defective.
If you suspect any part of the auxiliary (ribbed) belt drive is defective I would avoid running the engine until it’s repaired. A broken aux’ belt can break the lower timing belt cover and take out the timing belt resulting in catastrophic engine damage.