Humming noise coming from gearbox area

[Bobby~d]

Good day folks. I have a 2001 vr4. It's a manual yesterday the car worked fine and last night I launched it from a rolling start and since then I'm getting a humming noise coming from the gearbox area. The noise is more or less consistent now weather it be I'm driving between 20km/h - 180km/h. It goes sometimes but it soon comes back. All fluids supposed to be in great condition ( gearbox, transfer case & diff ) so I have no idea what could be causing the humming noise. Also checked all wheel bearings and they are fine. The car pulls and drives like normal but there is that humming noise.
Any ideas on what it could be cause I'm stumped? All replies would be greatly appreciated.
Edit the noise is there weather the car is in a gear or even if I take it out of gear and its rolling along in the speeds mentioned above. With the clutch pressed or not it's still there.

[rajvr497]

drain the gearbox/transfer case oil and check for metal particules stuck on the magnet....

[Bobby~d]

Was going to do that today but the weather did not permit me to. I'll definitely do it tomorrow thanks for the response. What will be the next step if no metal particles are found? Well I know if I find metal particles most definitely wherever I find it. That part has to come out.
Thanks again for the reply and nice talking to you on the phone.👍

[Bobby~d]

Drained all oils and sad to say that the transfer case oil was like gunk. All the others was good. Flushed and changed the oil in the transfer case twice in the last month. The car works fine but the noise which I discribed is still there. So I guess it'll have to either be replaced or repaired soon. Does anyone know how hard of a job this to do?

[wintertidenz]

Not the most fun job while under the car.
Remember to pull the transfer shaft first before undoing any transfer case bolts, and there are a couple of bolts that have to be undone from the top. You will need several extensions and probably one of the universal joint adapters IIRC.

If you need to do the clutch at the same time it's far easier to swap the transfer case with the box out of the car.

[Bobby~d]

Great thanks for the advice.

[Bobby~d]

Just a little update on this got a transfer case from rajvr497 a little while ago with some great advice on how to replace existing one on the car. Had a friend come over and help me remove the old one and install the new one I got and went for a test drive and the noise was gone. Took the both of us around three (3) hours to do. The three bolts to the top was really hard to access and remove but we got them out and the rest was easy. Thanks again Raj 👍 was a pleasure meeting you.

[Davezj]

here is a tip for next time with regard to the bolts on the top of the transfer case.

you need a strong stobby spanner and a length of wood and hammer.

put stubby spanner on the bolt so you can push down on it to undo it,
put the wood onto the top of the spanner and give the wood a good whack downwards.
this will be enough to get the bolt to start turning, then it is just a case of getting a short ratchet to get the bolts out.

took me a while to work out that this was the easiest way to get the top 3 bolt undo but for anyone else doing this job just try it you will love how easy it is.

[Bobby~d]

Yeah Dave they were a pita to get out I bought a new spanner and bent it outward to get the leverage but it started to slip. Then we tried from below with a swivel tip for the socket and that worked like a charm for the two(2) behind bolts. Then for the front one my pal did exactly like you said with the stubby spanner and that worked. Thanks for sharing on how to get it done 👍.