Whistle at idle - vacuum leak, induction side

[RichieRoo]

Well, everyone seems to be thinking along the same lines... some kind of liquid.

I might try a little WD40 or silicon spray perhaps that won't damage anything
back there. I should only need a little to identify it - I reckon the liquid will
momentarily block the leak a stop the whistle for a split second allowing me
to narrow my search area.

I'll give it a go and report back. Thanks for the ideas.