Your thinking to much about this... Cooler weather will do this. Let your tractor warm up a bit before you start using it during the winter
You are probable exactly right. I do over think ALOT. :laughing: It is just I never remember hearing this noise before and I have gone through 6 winters and 6 hydraulic oil changes with this tractor. What a coincidence it would be if the pump started going bad at the same time I did the oil change, but that seems to be my luck.:confused3: