Whining noise

[veebs]

I enjoy a good bit of guesswork as much as anyone, so opening up to the forum: what is the high pitched whirring noise you can hear in the video?

Some key points:
- Usually only downhill, light accelerator
- Has been getting more pronounced, though only slowly
- Varies in pitch very directly with the accelerator - no lag to rev up/down the engine
- Heavy accelerator, uphill, or high revs make it disappear
- Typically around 1,500 - 2,000 RPM. Any more, and it vanishes
- Sounds much louder than the video would have you believe
- Sounds to be coming from the right side of the engine (ie, driver side in Australia)
- No error codes (relevant ones anyway)


https://youtu.be/rVQyck-yBN4

[PerthDisco]

Last of the Interceptors

[trout1105]

Alternator ??

[Stuart02]

My car has a whine too, light acceleration approaching 2000rpm. Was thinking turbo but then the car's hesitating to shift up so I'm thinking transmission. Heavy engine braking (2500 to 3000rpm) can produce a much louder squeal.

Yours is a bit more of a whine, perhaps?

[Eric SDV6SE]

Alternator or idler bearings. Is the noise present if coasting? If so, I'd be looking at wheel bearings, but they are normally more of a rumble.....

[DiscoJeffster]

Alternator or idler bearings. Is the noise present if coasting? If so, I'd be looking at wheel bearings, but they are normally more of a rumble.....

The noise is aligned to the engine not road speed so it’s not wheel bearings. I’d look at something on the ancillary side like you say. Idler etc

[Briar]

Alternator was my first thought. How many Km on the Alternator. It seems like many have replaced theirs after 7 years or so. Mine was done last year at about 165,000.

[veebs]

Thanks all for the responses so far

Alternator was done about 90,000km ago, so I’d be disappointed if it had failed. The first one lasted to only 132k…

Idler pulley sounds possible… not sure why only on a downhill though?

Yes, coasting, but needs slight power to bring on the noise. I accidentally bumped a paddle shift under engine brake with a trailer on which also triggered it, but I’m guessing the engine still revved to match rpm with the gearbox or something?

My own fear was turbo related…

[Eric SDV6SE]

Thanks all for the responses so far

Alternator was done about 90,000km ago, so I’d be disappointed if it had failed. The first one lasted to only 132k…

Idler pulley sounds possible… not sure why only on a downhill though?

Yes, coasting, but needs slight power to bring on the noise. I accidentally bumped a paddle shift under engine brake with a trailer on which also triggered it, but I’m guessing the engine still revved to match rpm with the gearbox or something?

My own fear was turbo related…
Give it the berries and if it is a turbo, the red triangle will soon confirm it if it doesn't make boost.

But seriously, Whine is usually from rolling element bearings, turbo's on these engines are plain (sleeve) bearings running on a hydrodynamic oul film, so I don't think its a turbo.

What is odd is the rpm range of 500rpm where its most audible. A failing idler bearing would be noisy at all rpm, so maybe just starting to exceed allowable clearances.

I like this guessing game

[FisherX]

It sounds throttle dependant and sounds like a sucking noise.

Air leak in the intake track linked with vacuum, noise disappears on boost, maybe.

[veebs]

All sound plausible - I think it started not long after the intakes were fixed…

[RANDLOVER]

It sounds throttle dependant and sounds like a sucking noise.

Air leak in the intake track linked with vacuum, noise disappears on boost, maybe.

Could be the old vacuum brake booster check valve oil leak, and mine could be heard when facing downhill, but was more of a gurgle.

[Anton]

Hi Veebs, I'm sorry to say that I have the exact same issue and now know what the cause is. The noise stems from your exhaust manifold RHS bank. The common concern is that the studs holding the manifold on the head break off, usually the the last one or two studs, closest to the firewall. Myself and an Indi spent a few hours yesterday on my vehicle diagnosing the same, coupled with several hrs of research we came to this conclusion. Its a body off process, though I'm sure there are some brave souls out there that would attempt the manifold gaskets in place.

I'm due to do mine in the next week or two,

All the best

[harbspan]

Hi Veebs, I'm sorry to say that I have the exact same issue and now know what the cause is. The noise stems from your exhaust manifold RHS bank. The common concern is that the studs holding the manifold on the head break off, usually the the last one or two studs, closest to the firewall. Myself and an Indi spent a few hours yesterday on my vehicle diagnosing the same, coupled with several hrs of research we came to this conclusion. Its a body off process, though I'm sure there are some brave souls out there that would attempt the manifold gaskets in place.

I'm due to do mine in the next week or two,



Hi Anton, Let us know if this fixes the problem, and Veebs, If you get the same diagnosis and what the result is?
Thanks guys.

LesH.

[veebs]

Well, same diagnosis. The indie here heard the video and immediately diagnosed as snapped bolts on the exhaust manifold. They’ve seen 3 or 4 of these now.

Depending on which end (to be confirmed) this is a body on or off job. If they can access the broken bolt with the body on, it’s drill it out, thread a fresh one in and tighten. With my run, I’m expecting the body to need to come off though :-(

No price as yet, as the big boss wasn’t in when I got there, but bracing myself…

[Eric SDV6SE]

Sorry to hear that veebs, any clue as to why? Did the recent manifold job requite the header bolts to be touched?

[PerthDisco]

Everything a cinch with body off

Top Tip is set the chassis on jack stands so the top lines up perfectly when you drop it down.

Hard to believe it’s still driving with a knock like that

Land Rover Discovery 4 3.0 Engine swap - YouTube (https://youtu.be/3NEkIdUg4mw)

[Eric SDV6SE]

Good time to start a "While I'm there" thread

[PerthDisco]

Good time to start a "While I'm there" thread

That plastic block coolant fitting

Rear timing belt

Air con pump

Turbo/s

Manifolds / EGRs

Rear park brake

[veebs]

How about the transfer box? I have a floppy chain in there I’m told…

[harbspan]

Landrover Discovery 4 3.0 v6 turbo and exhaust manifold removal - YouTube (https://youtu.be/ZsgVCU_N0Bc)
Landrover Discovery 4 3.0 v6 broken exhaust manifold studd removal#landroverdiscovery4 - YouTube (https://youtu.be/wHxpWKIOMvI)

Doesn't look too hard to get at with body on. The fuel pump belt is harder to get at and that can be done body on too. If you had both to do then body off would be the way I'd go...but I have access to a hoist. If you're handy with a spanner and you didn't have a hoist you'd get it

[Eric SDV6SE]

Re the broken stud, that to me is a manufacturing defect, all manifold mounting holes should be clearance holes oversized to allow for thermal expansion of the cast iron. Looks to me like someone forgot to ream out the last hole. For location, they should have used a dowel pin or collet.

Good work to get the turbo out and drill the stud and remove.

[veebs]

So to circle back, this was definitely an exhaust manifold leak, and took a 'body off' to fix it. Whilst he was at it, I had the turbo changed out, and it turned out the alternator needed doing, so that went on too. A $10k repair bill, though the manifold is probably only about half that...