Whining gearbox?

[LarsoyH]

Hello everyone!

I have a 1.0 65hp 2005 model year yaris which has done 220000km (135.000miles) with a manual 5 speed gearbox.

Recently I have gotten a whining from what I believe is the gearbox.

It is mostly heard while in 2:nd and 3:rd gear, and during low revs (under 3000rpm).
Both during acceleration and deceleration.
In higher gears and during higher revs it is still there, but much quiter.

The whine is only heard when the car is rolling, and it is dependent on engine rpm, not the wheel speed. When I put the clutch in and rev the engine the whine is not heard, and if I shut off the engine and let the car roll in gear it whines a bit, but not nearly as much as when the engine is also running.

I have changed the auxillery belt, water pump, alternator, AC pulley bearing and both idler pulleys without any change in the whining.

I had the clutch changed before the whining started, but I drove the car for several weeks with the new clutch before the whining started, and it has gotten progressively worse since.

I have noticed a slight drop in MPG during the last few months as the whine has progressively gotten louder.

I guess this leaves it to be the gearbox?

Or could it be the timing chain even though the whine is not heard when free-reving / idling?

I have changed the gearbox oil 2 times, both with recomended 75W90 as the manual and also Toyotas 75W oil, without any change in the whine.

There were no noticable chunks or debris in the oil when I drained it, just a little bronze glitter, but not more than usually.

The car drives wonderfully and changes gear problem free, so I just cannot get my head around what is wrong with it. Is it normal that Yarises start to whine with age or is my gearbox running on overtime even though it feels as usual?