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)

[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.