My 1.4 petrol octavis is 3 yrs. old I have recently heard a 'hissing', just as I accelerate from idle. ( need to have door open to hear this ) There is also a 'new' noise as i drive.. on acceleration, alongside my usual quiet engine noise, I can hear a sound that has a resemblence to a howling wind ( best way to describe ) not too loud, but can be identified running alongside my very quiet engine, increases with and decreases with the driving pattern. any ideas ? thanks david.

Loose intake hose? Inlet manifold gasket leak? Or is more of a dry bearing noise? Does it run OK otherwise?

Thanks for the reply.. I suppose it could be any one of the the possibilities that you mention, I'm no longer able to understand 'under the bonnet' as I used to many years ago. Could trace and correct many odd faults when I was a young man. The momentarary 'hiss' when I stand outside and touch the accelerator could be 'normal' for all I know, It was whilst trying to identify the strange noise alongside the engine noise, that I heard this initial 'hiss' as I acclerated. Whilst driving, I could could just about hear the engine acclereating before..I can still hear the smooth engine revs, but this sound that is like a low-pitched howl isn't VERY loud, but I have to listen carefully to catch the usual smooth acceleration and deceleration ( this 'howl' responds in volume as I speed up and slow down..but it ISN'T anything like 'deafening'..just never heard it until about 5 days ago. The vehicle is just 3 weeks out of it's warranty ! and I'm afraid of being 'conned' if I take it to the dealership. It's due a service in August, I'm wondering if I should 'hold out' 'till then, or on the other hand, could this cause more problems, unless 'things' get worse...