240 General: Low-Pitched Whine At Slow Speeds

[TheHungriestBadger]

Hi all,

Just replaced my transmission mount (1990 240GL, B200F, AW70 trans) with the help of a mate, and now I have a new noise. As in the title, I have a low-pitched whine at slow speeds (possibly at higher speeds but it's very quickly overwhelmed by road noise). I have two analogies, take your pick:

1) It sounds like the noise modern EVs make when travelling at slow speeds.
2) It sounds almost identical to the electric window motors in pitch and 'coarseness'.

I'm hoping it's just something like the centre carrier bearing rubbing, or something along those lines, and not something more sinister. It's speed-dependent and not RPM-dependent, so far as I can tell... Radio was fully turned off as well so unlikely to be noise from ignition interference.

I'll likely be dropping it off at a local trusted garage at the earliest possible opportunity unless someone on here tells me to quit worrying and just 'send it and see'. Would be good in the meantime to have some possibles on what it could be.

Given the fact I've just replaced the trans mount, I'm guessing it's to do with the driveline at some stage? Also, by slow speeds I mean 20mph or less, above that there's too much tyre noise to discern whether it's still there. Noise is present both when coasting in gear, and when accelerating, I haven't tried coasting in neutral yet.

Finally, it's NOT the noise made when the transmission filter is clogged - my trans makes that noise only when first pulling away from cold and it's much higher-pitched than this new noise.

Cheers in advance,
Adam