I have a 2005 Nissan Altima SE with a manual transmission. The clutch was completely replaced about 7k miles ago. I bought the car about 5k miles ago. At around 2-3k miles ago is when the problems started. At first, once in awhile, I would notice very minor resistance going into 2nd gear only when the car was cold. By Minor I mean a very small and quiet "crunch", or like a split second grind. It would disappear very quickly, maybe after around a couple of minutes. This slowly worsened. Then probably somewhere around 1.5k miles ago, again only while the car was cold, I would hear a whining kind of noise whenever I accelerated fast in 1st and 2nd gear (I don't mean pedal to the floor) or if I had it sitting at lower rpms for cruising in town and put the pedal down it would do it also (like 3rd gear going ~20-25mph, probably around 1700rpm).
Currently, 1st gear once in awhile puts up a minor fuss like 2nd gear first did, and 2nd gear is at a pretty decent grind when shifting into it while its cold. 2nd gear will do this longer now too, pretty much until the car is fully warmed up. This is what I have gathered so far (feel free to correct me if I am wrong anywhere, I'm not saying that these are right or even make complete sense):
My friend, who was an auto tech, says the whine is from low transmission fluid. Which would make sense with the temp issue because once the fluid heated up and was circulated/distributed better the parts would be lubed up better. But I am nearly 100% positive it is not leaking, because I have multiple times placed pieces of cardboard underneath after driving to catch any drips, and haven't caught a single one.
Another problem that makes sense would be the clutch dragging. If that were the case then the syncros would be worn down and the tranny could heat up enough to start burning the fluid.
I am going to check the filler plug in a few hours to see where the fluid level is. So can anyone throw me any ideas/suggestions? Anything will help. Thanks!
The cause of the shifting problems was from low and burnt tranny fluid. As to why it is low I have no idea. It was changed roughly 8k miles ago. I couldn't catch any drips coming down either. I do now know that my syncros are brass and because of that my car requires gl4 gear oil. Gl5 eats away at yellow metals and will wreck my syncros. So I suppose it is a possibility that the dealer just didn't care and threw in gl5. I will update my answer and mark this question as answered when I bring my car in and find out what caused the condition of the fluid.