help me isolate this noise!!

[atlzhp6m]

I have been driving my 89 325is MT for almost two weeks and since day 1 I noticed a noise coming from under my shifter/transmission area. At first I thought it was the fan that blows air into the cabin but quickly realized it wasn't related to that. The noise is very hard to describe, it sounds like a piece of rubber hitting against moving blades of a fan... sort of. My car is a 1989 325IS with a 5 speed manual transmission. These are my observations: Noise is present while car is parked and you rev the engine. The noise is NOT present while car is parked and the engine is just idling. The noise is always there as long as you are on the throttle, regardless of the clutch being engaged or disengaged. The noise is not speed dependent, you can hear it as soon as you get on the throttle on first gear and it is present throughout all of the gears, although the intensity of the noise drops with the higher gears (maybe because everything is spinning faster??). I did some research on here and it seems like a lot people have had problems with their driveshaft and its components. I got under the car yesterday and noticed that the flex disc or "guibo" looked fairly new, so that's out of the question. I wasn't able to inspect the driveshaft bearing because that requires dropping the exhaust and heat shields. I will be replacing the transmission fluid and LSD fluid this weekend, so I will take a closer look, in the meantime, do you guys have any other suggestions or have you experienced the same type of noise? By the way, I bought Redline MT Fluid for my transmission and Redline 75W-90 for the LSD.

[jlevie]

Noise is present while car is parked and you rev the engine.

That says the the problem isn't with the drive shaft or further back. it could be a bad throwout bearing or some other problem with the clutch.

[atlzhp6m]

I'm leaning towards the clutch. But you are right, I guess we will find out sooner or later.