With a 7.5 fisher xv I barely hit 200 ect. Trans will get up there too but haven't hung a blade since the build.
Fwiw, the back of your plow says don't go over 45. I hate nanny warnings, but cruising fast hanging a heavy blade is asking for issues. That being said, should definitely not be puking coolant, especially in mid winter haha.
Cleaned your center stack at all recently? That's where I'd start