noisy idle noise - "diesel" like sound

[Beelzy]

Sounds like the water pump. Mine made the same noise right before it started
dumping coolant.

[ndfrigi]

Have u tried opening the engine access behind the seats? try to use a plastic tube and use it to hear each part of the engine where the noise/sound is coming from.
Water pump, idler pulleys, alternator, power steering and AC motor.

[Bruich10]

My waterpump went down 5 years ago at about 125.000 km - sound maybe similar but much more aggressive - and if the sound came “lately” it does not correspond with my wp experience.
Mine was: Sound - leak - wp bonkers!
But of course it is worth checking everything,