Old thread - Looks like I replaced one side cap 3 years ago. Had to replace the other side this year. Advice would be to do both sides at same time. It is easier to work on a clean hydro than one covered in muck.
@ smackerquacker: My 2014 John Deere z915b had the cracked/leaking cap also.
Thanks for everyone's previous comments on this topic. Helped a lot!
My notes after replacing the faulty cap:
1. Cap replacement part # was MIU14382
2. Directions "Remove and Install Fan Assembly" - Fan Assembly Lock...