So my car has been making this noise while reversing. Link to the video of the noise.

It's a 1997 B230fk, M90.

What do you guys think this is?

 

Try reversing in a straight line. If it only does it while you turn then the issue is with your power steering - loose belt, worn pump, low fluid, leaking rack, etc.

 

I'm pretty sure it's not steering related. I've editted the post changing the video. On this one I drive it on a straight line. It only makes the sound at clutch point. I'm thinking it's either related to speed, only manking the noise at low speed, or clutch/gearbox related. Could be driveshaft I guess. Brakes. Who knows. I certainly don't, unfortunately

 

It does sound like a P/S pump, but it's not if it only happens with the clutch activation. It's most likely in the clutch area, the transmission has to come out.

 

the clutch works the same forward and reverse.
my guess is it`s tailshaft support bearing. U joints, ,id feel for backlash with a back wheel off the ground. have someone move it back and forth to sort of hammer it while you put ypur hand on parts to sense the play or movement..check motor and tranny mounts too.

do it in gear ebrake off and blocked up safely.

the driveshaft components reverse in driven direction and the moment of noise is when that load first changes direction. that`s what leads me in this direction.

 

I am yet to completely confirm this. But I'm very confident saying that in this situation this noise is due to low fluid level on the transmission. It was pointed out by someone on volvo forums uk that it could be the reverse idle shaft making the noise, because it was above the fluid level (or rather the fluid was bellow).
This was made worse by the fact that I've been parking the car downhill recently, so the already low fluid level was pushed to the front of the transmission.
This theory is further validated by both the fact that after driving for a while the car would stop making the noise (because it got lubricated during driving) and by the fact that swaping the direction of the car at the parking spot, with the front of the car facing up, forcing the oil to the rear and therefore submerging the rev. idle shaft which caused the car to not make this noise anymore. (It also never did it if the car was parked on level ground, I just didn't connect the dots)

I'm yet to check the level because I'll just order the oil first. But I'm pretty sure that's it. Quite a weird one I guess.

For future reference if anyone has a weird accute squeaking noise only in reverse driving uphill that goes away after driving a bit, check the tranny fluid level.

 

Well, let's hope that this is it. Check the oil level, change it while you are there, and let us know.

 

UPDATE

It took me a while because the plug wouldn't come out so I had to order a breaker bar.
Today I went under the car, with the front on jack stands (not too high, but high) and when I opned the fill plug, oil started coming out. I lost a bit of oil but not too much I don't think.
This leaves me with 2 question:
First: Is it possible the front was too lifted that the hole was dropping oil even though the level was low, or does this defenitely prove the level wasn't low in the first place?
Second: Does the car need to be absolutely level in order the change transmission oil?

I kind think the car's front wasn't lifted enough for the hole to drop oil if the level was low to begin with. So that leaves me with the same issue from before, but more confused than ever. Because the theory did make a lot of sense, since the car stopped making the noise when I started parking uphil isntead of downhill.

PS: the oil that did come out looked super clean and didn't smell bad or anything.

 

Sounds like your oil was fine. Car should be level but let's not be fanatical about it. If it started pouring our, there was plenty in there.

 

Yes, I believe there was plenty. At least surely enough to cover the reverse idle shaft I think.

I'm back to square one on this issue.