"Rushing air" noise when engine under load when hot

So... driving to Gaydon today with the vehicle loaded & caravan in tow with my 300Tdi automatic Disco... towards the end of the 2 hour journey (the last 10 miles) the sound of rushing air started to come from the engine bay when the engine was under load.

Revving it in neutral did not generate the noise and it was not related to road speed.

I guess it's therefore not the viscous fan.

Definitely came from engine bay, so not gearbox.

Oh, and no split turbo hoses (as far as I can see).

It did sound like it was turbo related

But it sounded like whistling/whining... Hard to say which. Just sounded like lots of rushing air.

So... Whaddya reckon??

I would say that from your description it sounds exactly like when the viscous fan clutch locks up to cool the engine.

Let it cool down overnight and see if it does it in the morning. Also, before starting the engine check the fan to see if it is easy to turn or has permanently locked up.

Could be inlet manifold gasket, intercooler leaking, split or loose turbo hose.

Ok, so I've had a look...

Out the back of the turbo, underneath the inlet hose comes a small tube, similar in size to the vacuum hose. It goes straight into what looks like a T-piece with the "stem" of the T going towards the right of the vehicle (as you sit inside the cabin) back into the engine block through a 4" long piece of similar sized tubing.

One end of this had come off. I've reattached it, but don't know if it's stopped the noise yet.

Any idea what that hose does and could it have caused a whistling/rushing air noise under heavy load??

So... Does anyone know what that 4" long piece of vacuum-style tubing coming from the back of the turbo and going into the engine block is for?

Anyone?!?

vaccum hose is pressure feed for turbo waste gate and injection pump diaphragm

Do I have an injection pump diaphragm? Mines a '97 auto with a MAF... which I'm told means I have EDC instead.

As for the wastegate, where is it situated? Seems ridiculous to drill a channel through the crankcase rather than just put a pipe round the engine.

Finally, you say it's a vacuum hose, but although it looks like a vacuum hose, it's on the pressurised side of the turbo...

didnt mean hose was used for vacuum ,never seen a pipe like you describe going into block ,edc has pipe going to valve on bulkhead

Ok... so there is a vacuum-like hose that comes out the back of the turbo, at the bottom, and then comes up to something with a wire going to it bolted to the bulkhead. That is indeed the EDC & EDC hose.

However, on that same hose, at the turbo end there is a T-piece which then has a shorter piece of hose going straight into the engine block.

My vehicle has it and so does someone else's here at the convoy.

Neither of us can work out what it's for though! Very strange indeed...

are you sure its not going to wastegate diaphragm theres nothing on block to go to

Could well be... where's that located?

behind turbo

It must be going there then... Slightly behind turbo, slightly lower than the turbo and closer to the engine block?

Ok, found a 300Tdi turbo picture...



Looks like it is the wastegate after all (see blue pipe).

One end of the hose you see here had come off, so that probably explains why I heard rushing air every time the turbo spooled up!

I didn't notice a lack of power, but was driving on roads I've never driven on before anyway (bit hilly, lots of corners)!

you wouldnt notice lack off power,it opens wastegate,relaitive to pressure of boost ,so in effffect you could get higher boost pressures at high revs ,can be a problem on td5 were wastegate gates stuck and higher pressure confuses ecu giving fault

I meant I didn't notice lack of power when the hose came off.

Surely with that blue hose disconnected, not only would it be the same as having the wastegate permanently open, but the EDC would be receiving less pressure and therefore delivering less fuel?

no wastegate is sprung shut thru actuator diaphragm,it is opened by turbo boost,hence the name wastegate it reduces boost above set level

Yes, but although it is sprung shut, if the pressure hose going to it is detached, then would I not lose all my boost pressure through the opening where the hose should be? ...therefore being the *equivalent* of having the wastegate stuck open?

small hole large flow,hose goes to actuator diaphragm ,wastegate is connected by adjustable rod in hot exhaust gas side

I know... but if the blue hose you see in the picture came off, what would the effect be?

I assume all the turbo boost pressure would simply leak out of the brass nozzle into the atmosphere, therefore giving the equivalent effect of having the wastegate stuck open... right??