My gears were grinding on the downshift from second to 1st and on the upshift from 2nd to 3rd. I took it in and the syncro's for all the gears were replaced. Some bearings were replaced, not sure what ones and clucth was replaced. I have been driving the car for no more then 300 km since then and i am noticing a grind on the upshift from 2nd to 3rd when I shift above 4500 rpm. Could there possibly be any other problems that the mechanic may have overlooked? I don't think its possible to blow the syncro in 300 km.

 

Shouldn't be doing that right after a rebuild. I would speak with the technician.

Try the "pump fake" shift into 3rd. Push out of second and move it into neutral very quickly and slightly towards 4th before shifting into 3rd. In other words, the lever should slide STRAIGHT into 3rd not on the typical 2-3 angle. Kinda weird but stops all 3rd gear grinds.