I have a Daewoo Lanos with a manual transmission. About a month ago I changed the whole clutch set. While in idle, there is no noise at all, it idles beautifully, but when I am about to pull out from a stop, noise from the transmission area comes out, like a "grrrr" until I catch up some speed it vanishes out. It shifts gears normally, but just that that noise is annoying especially when I come close to a wall I hear it more clearly. The best I can describe that noise is like this, "grrrr". It used to a make a similar noise like that while idling before I replaced the clutch set, but that noise use to disappear when I depress the clutch pedal, and appear when I release the pedal. Turned out to be the release bearing, so I decided to change the whole clutch. No more of that noise, now there is this one, the "grrrr".
Yes, checked transmission oil, it is good, and no leaks. I also forgot to mention, when engaging first to second gear, or from second to first gear a weird clunk noise comes out, checked all mounts all are good.