is there such a thing as "bleeding" out the hydro air?

[Brockport Bill 1,363]

is there such a thing as "bleeding" the hydro air out? After draining the old oil - then when filling with new oil, I assume there are air pockets remaining in the transmission and hydro hoses, the lift cylinder, etc -- so is there such a thing as " bleeding" or some how getting the air out ? I assume the published oil volume includes the volume capacity of liquid? Do we need to bleed out air to fill the tranny to the proper oil capacity - if so - how? thanks - still learning!!!!!!!!!!!

[pfrederi 17,114]

I will only speak to sunstrands.  No bleeding required.  Just work it forward backwards and use the lift if so equipped  a few times...  Then recheck you fill level.

[Handy Don 10,522]

1 hour ago, pfrederi said:

I will only speak to sunstrands.  No bleeding required.  Just work it forward backwards and use the lift if so equipped  a few times...  Then recheck you fill level.

SM for the Eatons says essentially the same. Start the engine and at low RPM cycle the lift several times. Then drive forward and backward several times slowly and then at full speed. Then check the oil and add as needed.

[Brockport Bill 1,363]

so here's a follow up question - ( it's a 520HC )  - and thanks for that info -- where does the air go? Seems like there would be an "air bound effect" -- i  dont know a technical term. I suppose if the fill tube is used for the second filling "topping off" the oil after doing the tractor movement you suggest then we would expect the oil to displace the air ? yes/no?  But how does air escape????????

As a side note when i did the tranny oil change - i added the new oil through the fill tube.... but i had totally removed one of the two bolts in the top of the tranny housing that holds seat bracket down allowing for "venting" -- but now i have those two bracket bolts reinstalled. Thanks again !! I attached 2 photos of before and after cleaning and some modest painting - the tractor was covered in "black caked oil" when i got it this spring.

[lynnmor 6,760]

The curl on the dipstick has a small opening in the end for a vent.  Often that opening is blocked with debris or the curl is crushed, so check that it is clear.

Edited September 7, 2021 by lynnmor

[kpinnc 10,641]

I've seen mine "burp" on occasion. Usually after a service, and doesn't do it again unless it's pushed a bunch.

[Handy Don 10,522]

2 hours ago, lynnmor said:

The curl on the dipstick has a small opening in the end for a vent.  Often that opening is blocked with debris or the curl is crushed, so check that it is clear.

Mine originally had some dirt/oil, not sure if it was actually clogged. I cleaned it with a long pipe cleaner (pinched from my grandkids' art supplies bin) that I sprayed with "gunk remover". Took just a minute.