I have a 2004 Honda Accord EX V6 VTEC 3.0 6 seed with 135,000 miles. It's starting to grind going into 3rd gear after driving it for about 20 miles. Everyone is saying that it's the synchos, but I'm just grasping that it could be something else since I had a "new" used transmission put in recently, in November. Any suggestions or at least a temporary fix?

I purchased the car in July of 2011.

March 2012 clutch was replaced
May clutch hose was replaced
June engine and catalytic converter
Sept starter
Nov transmission and brakes

$5,660 in repairs!!

 

3rd gear sleeve is probably worn and chewed up, the hub may be as well, and the 3rd gear synchro may or may not be worn. Worst case it's all bad along with 3rd gear itself and the 3rd/4th shift fork.

 

3rd gear is shot . You need a 3rd gear set . Typical problem with only one real fix .