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I've noticed this quite a lot recently.

The symptons are;

Accelerating fairly hard (i.e more than 50% pedel down) and using more than 2500rpms

There is a sound entering the cabin by the sounds of it through the dash vents (Sounds like drivers side one to the right of the steering wheel to me and the wife says the centre vents which I can also confirm.

When stationary and blipping the the throttle we can't hear it (Probably because of the diesel noise and engine not under load)

But what could this be? I'm not sure its ventilation system as no more air enters the cabin by feel, but its seems audible through the air vents...

Could it be a boost leak? (Mine is a 90 HDi with no Intercooler) or maybe a split hose somewhere?

Any kind of feedback or where to look would for possible solutions etc would be great as its really strange sound.

Im also 'only' getting 35mpg whereas the misses estate with the same engine on similar route is nudging 4-6MPG more. But mine does not seem slugish.

I should also mention I dont have the MIL light on.

Just thinking, what about a failing EGR? Would that cause an airl leak as its close to the bulk head and could explain why its entering the cabin?

I guess it must be some sort of leak, not sure about the egr - wouldn't your consumption go down?

Get 1 meter of hose pipe, stick one end in your ear and use the other to have a listen around under the bonnet. Not sure what else to suggest

Our old C15 vans used to suffer with the air intake pipes falling off.Pehapes the pipe between the air box and the manifold has split?

Im unsure how the MPG computer works but I average 35mpg in stop start traffic for 25 miles, yet doing a steady 70 for 10 miles did not increase the MPG.

But it only happens when I accelerate hard ish.

I guess it could also be described at a 'whirring' sound but not mechanical, deffo sounds like air to me.

Ill have a look later for any split hoses later on.

Not water pump as temps are fine (not that kinda noise really) or a belt.

Its a hard noise to describe which is annoying

I was expectingly slightly better than 35mpg though, the misses wagon gets 4-5mpg more on a similar commute

The intake pipe after the MAF to plastic pipe (Accordian type) it fixed ok.

One thing that is apparant is when my car has started and ive done a small commute or long commute OR started for 2 mins and then turned off there is like a low pitched quiet whine from the back of engine (bulkhead side) and it also kinda makes clicking sounds.

I got in the car with engine off and pressed the brake pedal several times, quiet hard and something in the engine bay made a clicking sound when I pressed the pedal twice then it stopped and brake pedal went hard and then went to listen for the whine and ithad stopped?

So im wondering if this 'air' sound when accelerating is linked to this 'whine' sound when the engine off and it seems to stop straight away as soon as the brake pedal is pressed.

So im guessing something on same vacuum solenoid?

Low pitched whine & clicking - check.
Could be a vacuum line off a solenoid.

Are the solenoids all situated on the bulk head?

Ill take a picture tomorrow for you guys to check them out as I dont what should be connected and what shouldnt be etc.

I know the EGR is hooked up, not sure about the other 2..

Clicking noise sounds like steering pump.See how bad the sound is in full lock.

N.B. sorry no I didnt mean cv joints clicking,more the pump when it is under full load.

PAS seems fine, slight whine from pump when on full lock but no clicking what so-ever...

I had a similer sound when accelerating on my Subaru Impreza. Turned out to be the input shaft on the gearbox. I also thought i had an air leak somewhere, try accelerating and then taking it out of gear while holding the revs. If the sound goes, then id investigate the gearbox.

musso2010 wrote:I had a similer sound when accelerating on my Subaru Impreza. Turned out to be the input shaft on the gearbox. I also thought i had an air leak somewhere, try accelerating and then taking it out of gear while holding the revs. If the sound goes, then id investigate the gearbox.

Interesting, ill try that on my way home

Ill also try just dipping the clutch too.

My bottom engine mount is shagged, also and sometimes my car really badly judders when bringing the clutch up or say when crawling in traffic now slow enough to put it into 1st, but 2nd and then engaging the clutch brings a load judders/vibrations.

I hope its not clutch/gbox related as thats £££££

Does it depend on speed or purely on the engine rotation speed? Mine was having some weird "whooshing" noise at over 60mph, which took me absolute ages to find. Turned out to be the radio aerial on the roof being extended too much upright generating the noise in the wind

Oh dear, Juddering doesnt sound good. I had that with the Scooby aswell, but they are notorious for being juddery when pulling away. Give it a try mate, Hopefully its not the gearbox.