Annoying Whine.

My 2007 Jimny has a whining noise even when in neutral. Makes this noise even when clutch depressed. I know that my Jimny falls into the bracket of the iffy gearbox that's supposedly made of chocolate. I have checked all the belts to see if the noise originates from that area and all is quiet.
Looked underneath and I have a light misting of oil between the gearbox and transfer box. I am aware of the issue of the unglued plug in the u-joint and assume that wouldn't be the cause of the whine.
My question is has anyone else had a similar problem and if so what was the culprit?

I have replaced all the fluids in the transfer box and diffs. I couldn't get the gearbox filler plug undone.I had to take it to a garage so they get it removed. They replaced the gearbox oil. I did ask them to inspect the old oil and let me know if it showed any signs of metal contamination or issues. But when I collected it I was told they were too busy and forgot to do as I asked. 

From vague memory my gearbox did not whine before the fail. More like a rumble. And mostly under load. But I only got a few km after hearing the noise before it crushed a gear wheel tooth.

If the noise continues when stationary, in gear with your foot on the clutch then it isn't the gearbox as it won't be turning.

It could be the release bearing, but they tend to roar rather than whine, and I'd expect a difference between foot on & off the clutch.

If you are Old like me and your ears are damaged from years of toiling in noisy environments/riding motorcycles etc. then it is impossible to locate a high pitched noise except by getting closer to it. The traditional approach is using a stick to conduct the noise to your ear, and moving it around likely places.

I'd start by turning the heater fan off and see if it was that.

then see if it is still there when the ignition is on but the engine stopped. (maybe it is one of the many warning squeakers permanently on, or even one of those parking sensors or the box that is fitted with a towbar to beep if the trailer lights flash)

If it is only with the engine running, start by looking for air leaks like cracked/broken pipes.

then dropping the belts off and seeing if it is still there

If it isn't any of these, then it can only be the fuel pump or something actually inside the engine.


My 2001 used to make a weird noise that I eventually tracked down to one of the headlight levelling motors hunting, moving the twiddler inside the car from the usual position stopped it.

My Gen 4 makes all sorts of odd whistling noises from under the bonnet when the ignition is on and the engine is stopped, probably the throttle motor, I can't tell.