I have an 09 vibe with 2.4L 5-speed and 155k miles. Still on original clutch, engine, trans, in fact no major parts have ever really been replaced other than brakes.
It started with a grind when upshifting into 3rd from 2nd, even with the clutch all the way on the floor. Now, itll grind upshifting from 1st to 2nd, and from 2nd to 3rd. Downshifting from 4th to 3rd makes the worst grind of all, and I get around it by always downshifting into 2nd and then back up to 3rd. The way i avoid all of this during daily driving is to pull it out of gear, count "1, 2" while the RPMs drop a bit, and then it slots into the next gear no problem.
My first though was that the synchros for 3rd and 2nd gear are trashed, which would require a transmission rebuild to fix. Ive also wondered about the master cylinder being a cause, however the fliud level is always fine (shares reservoir with brake fliud). Another guess is the clutch, it does have 155k miles on it. Another thing to note is that the shifter is sloppy as hell, tons of play in every gear, could this be a cause as well? Is that remedied just by replacing the plastic bushing right underneath the shifter? Ive also read that it could also be the shift linkage causing the grind between gears.
There are a lot of possible causes and i dont know where to start, i dont know how to for sure start to rule them out. Any ideas?