Strange high pitched whine/ringing sound...

[rosss]

Hello all,

My Bongo has started to make this odd high pitched wavering ringing sound... it starts to happen once the engine has warmed up and continues until i turn off the engine and remove the key. If I turn off the engine when the van is hot but keep the key turned so the electrics are on but not the engine it will continue to happen (which is as it is in the video.)
it's louder down by the drivers side footwell ... ( though i haven't listened on the passenger side...) -
i had to get the engine replaced some time ago... and i was hearing this sound before that happened ... which isn't good... though in that case i was leaking coolant... and when i refilled it this sound disappeared... which is kindof doubly odd because this time the coolant is fine. I would literally top up the water with a bottle i had in the car and when i started it again this sound was gone... (i'm fairly sure of this though it was a couple of years ago - which is to say, i may be wrong about that part.)
any clues?
Thanks!
(video link) https://www.dropbox.com/s/imuirwr80a4g1 ... w.mov?dl=0

[g8dhe]

Very difficult to hear on the recording, two possible sources come to my mind;
Either the Sound Warning System, which generates the Beeps, is perhaps making a noise, this is located behind the plastic panel by the drivers right foot a small module with a hole in the side for the sounder.
The Air Con flap servo is being powered up or is jammed and making the squealing noise, this is located on the end of the driven link just above the drivers left footrest.
Another thought do you have a Low Coolant alarm or Temperature alarm or any other added electronics which might be making the noise ?

[rosss]

Hi Geoff....

Thanks -
yes i have a low coolant alarm but it has a button on that i can press to check its beep - and that beep is much louder and different... this one has a wavering pitch and is higher and is softer... but i did wonder the same because of the apparent relation first time i had this noise to the coolant level.
I'll look into those other bits... thanks