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Sounds like a DUMP VALVE !
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LandyAndy68
 


Member Since: 20 Feb 2012
Location: Yorkshire, England.
Posts: 118

United Kingdom 2009 Discovery 3 TDV6 SE Auto Zermatt SilverDiscovery 3

Wow, I'm amazed there are so many people suffering the same as me. I'm going to check the hoses this afternoon and keep my fingers crossed its nothing more serious or expensive.
Thanks very much you all, your help and advice is GREATLY APPRECIATED.

ANDY
  
Post #108652911th Apr 2013 8:03 am
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stav
 


Member Since: 14 Nov 2013
Location: Athens
Posts: 178

Greece 2005 Discovery 3 TDV6 S Auto Unknown ColourDiscovery 3

Hi Andy, did you find out what was generating the noise?????
  
Post #119425328th Nov 2013 11:10 am
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crwoody
 


Member Since: 09 Mar 2009
Location: Littleborough
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United Kingdom 2006 Discovery 3 TDV6 HSE Auto Zermatt SilverDiscovery 3

Funnily enough I was about to ask a question on a new thread about the exact same subject, then I found this one Thumbs Up

My D3 had been doing the same as described here for some time, most noticeable when coming off the throttle and sounds just like excess boost pressure being released.

There's no noticeable loss of performance that I'm aware of, unless of course I'm just used to it, and it doesn't appear to have got any worse since I first noticed it, this led be to assume it wasn't something like a split hose which I would assume would get worse over time with increased deterioration.

The big intercooler to inlet manifold hose is new, having split a few months ago, but the comments here have now got me wondering about the other two smaller ones after the turbo, I guess I'll have to go and check Rolling Eyes unless someone has a better plan ?
 Clive

 
 
Post #119428628th Nov 2013 11:57 am
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stav
 


Member Since: 14 Nov 2013
Location: Athens
Posts: 178

Greece 2005 Discovery 3 TDV6 S Auto Unknown ColourDiscovery 3

Crwoody, can the sound be heard while coming on and off the throttle while in neutral???

Mine does it only when on D (autobox) and the car is moving. Not when stationary, hence its difficult to diagnose Confused Confused Confused
  
Post #119429628th Nov 2013 12:13 pm
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fishinmad
 


Member Since: 30 Jan 2012
Location: St Ives
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United Kingdom 2006 Discovery 3 TDV6 S Auto Bonatti GreyDiscovery 3

My car also makes this noise when coming off the throttle to and has done scince new (96K now), other D3's in my area make the same noise so I thought it was just something they did!
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Post #119432128th Nov 2013 12:59 pm
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crwoody
 


Member Since: 09 Mar 2009
Location: Littleborough
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United Kingdom 2006 Discovery 3 TDV6 HSE Auto Zermatt SilverDiscovery 3

stav wrote:
Crwoody, can the sound be heard while coming on and off the throttle while in neutral???

Mine does it only when on D (autobox) and the car is moving. Not when stationary, hence its difficult to diagnose Confused Confused Confused


No, like yours, it's only audible when moving, usually going uphill when the turbo is actually producing some boost, blipping the throttle while stationary wont produce the effect.

I was hoping that by now, someone might have come along to say "there's a boost over-pressure relief valve", never mind, I live in hope Confused
 Clive

 
 
Post #119436828th Nov 2013 2:54 pm
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stav
 


Member Since: 14 Nov 2013
Location: Athens
Posts: 178

Greece 2005 Discovery 3 TDV6 S Auto Unknown ColourDiscovery 3

Went to the most respected dealer in Greece today, had a ride with him, windows open, just to ask what on earth is this sound!!!!!

The reply was: "Its the EGR" , he also said that since mines are blanked i shouldn;t worry about it at all!!!!!!!!!! When i asked why other cars dont produce this sound, he said that my EGRs should be very dirty, and even if they are blanked they still work, producing the sound. Shocked Shocked Shocked

I have no reason to argue about what ive heard, and the reason is that this is the first mechanic giving a straightforward answer rightaway, without scratching his head Rolling Eyes Rolling Eyes Rolling Eyes Rolling Eyes
  
Post #119439628th Nov 2013 3:37 pm
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wizbongre
 


Member Since: 26 Oct 2013
Location: Liverpool
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United Kingdom 2016 Discovery 4 3.0 SDV6 HSE Lux Auto Fuji WhiteDiscovery 4

crwoody wrote:
I was hoping that by now, someone might have come along to say "there's a boost over-pressure relief valve", never mind, I live in hope Confused


Wouldn't that be the wastegate on the turbo? I assume D3 turbos do indeed have a wastegate?

I've just had my turbo refurbished (or fixed, or replaced, or left alone, depending on what mood the garage is in and how hard they want to try and explain what they've done!) and it now makes this slight whoosh noise as you get on the power and off, or at very low revs and light throttle. To me it sounds like the wastegate working to keep the boost up and stop the turbo stalling when at relatively low engine revs. I've heard lots of turbo diesels (and indeed earlier turbo petrol engines) make a similar noise and I'm sure my Audi A8 does it too but thanks to the half tonne of double glazing and sound proofing, I can't hear it like I can on the Disco! Thumbs Up
  
Post #119491129th Nov 2013 1:25 pm
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Gareth
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I am pretty sure that the turbo on a diesel engine does not have a dump or blow off valve. The reason is that on a petrol engine, the speed/power is controlled by a 'throttle' in the inlet manifold that 'throttles' the air rushing into the engine when you release the accelerator pedal, and a turbo petrol engine needs the dump or blow off to stop the inlet pipes downstream of the turbocharger exploding, because the pressurised air would have nowhere to go.

On a diesel engine, there is no 'throttle' as such (ok there is a butterfly valve in the inlet, but that only shuts when egrs are open). When you press or release the accelerator pedal, it increases or decreases the fuel supply to the engine. The diesel engine runs with the inlet tract fully open all the time, so no need to dump pressure when the pedal is released.

I think the noise you are hearing is either the air rushing through the pipes/intercooler (or a split/hole in either) or the turbo vanes spooling down.
  
Post #119491729th Nov 2013 1:38 pm
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beanie
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crwoody wrote:

No, like yours, it's only audible when moving, usually going uphill when the turbo is actually producing some boost, blipping the throttle while stationary wont produce the effect.



Same here, going to replace the pipes and IC sometime, will report back Thumbs Up
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Post #119492229th Nov 2013 1:44 pm
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wizbongre
 


Member Since: 26 Oct 2013
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United Kingdom 2016 Discovery 4 3.0 SDV6 HSE Lux Auto Fuji WhiteDiscovery 4

Gareth wrote:
I am pretty sure that the turbo on a diesel engine does not have a dump or blow off valve.


Maybe not a dump valve but do they have waste gate's on the turbos? These usually work to control the maximum boost the turbo can achieve by reducing the back pressure, allowing them to spool up and then when they reach maximum boost (say 1bar or whatever it is) modulating to maintain that pressure otherwise the boost would continue to rise.

That's my understanding of petrol engines at least and just assumed it would be similar for diesels although as you point out, with no throttle plate as such in the induction flow I'm now re-thinking my logic! Smile

I'm off to google turbo design on diesel engines... Confused
  
Post #119493429th Nov 2013 2:26 pm
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wizbongre
 


Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690

United Kingdom 2016 Discovery 4 3.0 SDV6 HSE Lux Auto Fuji WhiteDiscovery 4

Found an explanation already...

The variable technology in the turbo essentially acts as the wastegate, varying the pressure it can generate however diesel engines don't need to limit the boost and actually, the more boost the better.

So in short, I don't have a clue what I'm talking about and I need to go back to the drawing board as to why my car is whooshing... Razz
  
Post #119493729th Nov 2013 2:32 pm
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Gareth
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Member Since: 07 Dec 2004
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No wastegate on diesel turbo either as far as I know. The boost pressure is regulated electronically by the variable vanes, which alter the amount of exhaust gas entering the turbine stage.

I think wastegates and dumps are old technology now?
  
Post #119493829th Nov 2013 2:32 pm
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wizbongre
 


Member Since: 26 Oct 2013
Location: Liverpool
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United Kingdom 2016 Discovery 4 3.0 SDV6 HSE Lux Auto Fuji WhiteDiscovery 4

Yeah, think that sums it up.

To be fair, I was basing my knowledge on my Nissan Pulsar GTi-R which was built in the late 80's so not exactly cutting edge!
  
Post #119494129th Nov 2013 2:34 pm
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anglefire
 


Member Since: 09 Mar 2010
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England 

Is the whooshing noise coming from cars with auto's? And does the noise come from the near side?

If so, it is probably the plastic bracket that keeps the gearbox oil return/flow pipe away from the turbo pipework. Or its the turbo heat shields rattling slightly. Same sort of area.
 Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
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Post #119506229th Nov 2013 5:53 pm
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