I can not engage into 5th gear when on the move in my 2002 mercedes sprinter 311 cdi when in 4th and moving up to 5th it is like I have selected 3rd because the revs are very high when the gear stick is pushed into the 5th gear position .Can anybody give me an explanation as to why this mite be happening and how it can be fixed.
Many Thanks Paul

Paul, August 2009