Disco 4 (LR4) Whining Noise When Idle Goes Away Once Accelerating

My Discovery 4 (2010) just started making a whining noise when idling. As soon as I accelerate it goes away. There’s no performance loss just this annoying noise. I’ve attached a link with a video of the sound. Thank you.

ExecutiveOutcomes said:

My Discovery 4 (2010) just started making a whining noise when idling. As soon as I accelerate it goes away. There’s no performance loss just this annoying noise. I’ve attached a link with a video of the sound. Thank you.

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hi

wonder if it’s ur alternator , maybe take the aux belt off to see if the noise goes away ???

if u get chance would u mind taking another recording from the engine bay please as that may be more telling , thks

Welcome to LZ
Best to post in disco section for an answer

lynall said:

Welcome to LZ
Best to post in disco section for an answer

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Thank you. Will do mate.

gstuart said:

hi

wonder if it’s ur alternator , maybe take the aux belt off to see if the noise goes away ???

if u get chance would u mind taking another recording from the engine bay please as that may be more telling , thks

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gstuart said:

hi

wonder if it’s ur alternator , maybe take the aux belt off to see if the noise goes away ???

if u get chance would u mind taking another recording from the engine bay please as that may be more telling , thks

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Really appreciate your reply. I’ve been on a long run for n it today and it’s not making the sound so I couldn’t get another video of it. But on your advice I’ve listened to a few ‘failed alternator’ videos and I think you’re right. So it’s not going to be cheap but at least I know what it is. Thanks again.

ExecutiveOutcomes said:

Really appreciate your reply. I’ve been on a long run for n it today and it’s not making the sound so I couldn’t get another video of it. But on your advice I’ve listened to a few ‘failed alternator’ videos and I think you’re right. So it’s not going to be cheap but at least I know what it is. Thanks again.

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Does the d4 have a one way alternator pulley?

ExecutiveOutcomes said:

Really appreciate your reply. I’ve been on a long run for n it today and it’s not making the sound so I couldn’t get another video of it. But on your advice I’ve listened to a few ‘failed alternator’ videos and I think you’re right. So it’s not going to be cheap but at least I know what it is. Thanks again.

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Ur so welcome , if it is the alternator plse ensure u get a denso , plus out of curiosity the engine bay hasn’t been washed lately has it plse , , ie wet belt etc

have seen a video where they sprayed a small amount of water onto the belt to see if it makes the same noise

if u do need a new alternator plse ensure it’s made by denso , here’s some part numbers and link to a good company , they also do belts and pulleys etc

https://www.advancedfactors.co.uk/alternator-11684-c.asp

pulleys etc

https://www.advancedfactors.co.uk/auxiliary-drive-belt--tensioners-discovery-4--rrs-l320-11672-c.asp

hope that helps and plse let us know how u get on

lynall said:

Does the d4 have a one way alternator pulley?

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hi mate

must confess I’ve not been able to find out , know ur considerably more knowledgeable than myself

lynall said:

Does the d4 have a one way alternator pulley?

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I have no idea mate. I’m a complete newcomer to all this. Could you elaborate on your theory? Thanks

gstuart said:

Ur so welcome , if it is the alternator plse ensure u get a denso , plus out of curiosity the engine bay hasn’t been washed lately has it plse , , ie wet belt etc

have seen a video where they sprayed a small amount of water onto the belt to see if it makes the same noise

if u do need a new alternator plse ensure it’s made by denso , here’s some part numbers and link to a good company , they also do belts and pulleys etc

https://www.advancedfactors.co.uk/alternator-11684-c.asp

pulleys etc

https://www.advancedfactors.co.uk/auxiliary-drive-belt--tensioners-discovery-4--rrs-l320-11672-c.asp

hope that helps and plse let us know how u get on

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Thank you. Cannot overestimate how much this has helped.

lynall said:

Does the d4 have a one way alternator pulley?

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Would I be able to apply water to the alternator pulley to see if this is the cause?

ExecutiveOutcomes said:

Thank you. Cannot overestimate how much this has helped.

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ur more than welcome mate , glad it was of some use to u

know when I bought my D3 some 6 x years ago I had some fantastic help so always nice being able to pass any assistance on to others

indeed can just spray a little amount of water onto the belt to see if it makes the same noise

plus another thought ref noise and hope this doesn’t sound daft or rude but did u ensure ur fan inside the vehicle was also turned off, hope that doesn’t come across trying to teach u how to suck eggs , just wish to ensure nothing is missed

u can use a garden sprayer if u have one to hand as don’t need much to be put onto the aux belt , plus another thought try turning ur air con on and off to ensure it isn’t that either , just thought with the weather getting colder u might have switched it to heat and maybe a reason why the noise stopped , just an idea

lastly I’m pretty sure the power steering pump also uses the same belt , in the same token try moving ur steering wheel lock to lock ,

plse let us know how u get on and don’t hesitate to ask if u get stuck or unsure about anything

gstuart said:

ur more than welcome mate , glad it was of some use to u

know when I bought my D3 some 6 x years ago I had some fantastic help so always nice being able to pass any assistance on to others

indeed can just spray a little amount of water onto the belt to see if it makes the same noise

plus another thought ref noise and hope this doesn’t sound daft or rude but did u ensure ur fan inside the vehicle was also turned off, hope that doesn’t come across trying to teach u how to suck eggs , just wish to ensure nothing is missed

u can use a garden sprayer if u have one to hand as don’t need much to be put onto the aux belt , plus another thought try turning ur air con on and off to ensure it isn’t that either , just thought with the weather getting colder u might have switched it to heat and maybe a reason why the noise stopped , just an idea

plse let us know how u get on

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Haha no offence at all mate. As I said I’m a complete newcomer. I did make sure the air con was off but that’s a good point about the temp setting. I’ll try switching hot/cold and see if that makes a difference. The main thing that baffles me is that it’s not a consistent noise, it’s not there every time I start the car. But it seems when the car has been idle for a while or it’s cold outside then that seems to be a factor in causing the noise.

ExecutiveOutcomes said:

Haha no offence at all mate. As I said I’m a complete newcomer. I did make sure the air con was off but that’s a good point about the temp setting. I’ll try switching hot/cold and see if that makes a difference. The main thing that baffles me is that it’s not a consistent noise, it’s not there every time I start the car. But it seems when the car has been idle for a while or it’s cold outside then that seems to be a factor in causing the noise.

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many thks as never want my posts to come across as rude

Another thought, When it’s cold u should see the outside temperature display on ur instrument panel , if it drops below 7C ur fuel burner heater will come on, but doubt it’s that as the noise in ur video changes as ur engine revs change

indeed plse change ur temp setting to cold and leave it for 10 x minutes or so, ensure the vents blow out cold air and see if the noise comes back

just trying to cover all the basis of what items use that aux belt which I think consists of the alternator, power steering and air con compressor , then the tensioners which can of course also cause issues , so if u spray a small amount of water onto the aux belt and then get the noise back it might just be a worn out belt or tensioner where it’s not adjusting the aux belt to its correct tension

If ur unable to do the work urself don’t go to a JLR dealer because there so expensive , don’t know if u have an independent garage locally

hopefully as a way of elimination we can identify what’s causing the noise, ie noisy bearings in the alternator , tensioner, etc etc , plus not sure using ur ear and a long screwdriver placed on each item will help seeing its intermittent , slipping belt will normally screech

plse let us know how u get on when u get chance, thks

ps, also assume ur engine is the 3.0 SDV6

ExecutiveOutcomes said:

Would I be able to apply water to the alternator pulley to see if this is the cause?

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No as the one way clutch is inside the alt pulley.
The list of possible causes is endless, belt/belt tensioner/idler pulley/water pump/alternator/air con pump and so on.

ExecutiveOutcomes said:

I have no idea mate. I’m a complete newcomer to all this. Could you elaborate on your theory? Thanks

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Google it, loads of cars have them.