Hydraulic oil level

[NMNeil]

My 8N hydraulics are sluggish and when under load they raise the arms in a series of jerks. Difficult to describe, but it's like something is getting slightly stuck before releasing, and it keeps on doing this until the arms are fully up. When the arms are in the up position they will stay that way for days, even when loaded, so it's not a cylinder/piston leak.
I took off the top cover to test my new 3d printed adjustment jig to make sure it wasn't just out of adjustment but looking into the casing at the top of the pump the pump pistons are only about 3/4 submerged in the oil. The dipstick for the transmission oil is dead on the full mark but it just seems wrong as every time the piston moves it will be pressurizing oil and air rather than just oil.
Anyone know if the 8N's had different length dipsticks and if the oil level should be high enough to completely submerge the pump pistons?

 

[Roger in Iowa]

Oil level up to the bottom bolt on plates either side of trans rear of your heels is full enough level. Over full puts oil on brakes.

 

[NMNeil]

Do you mean the circular inspection covers, one of which has the dipstick tube built in?

 

[Btzj02]

Do you mean the circular inspection covers, one of which has the dipstick tube built in?

That is correct. Take the bottom bolt out and add oil until it drains out the hole. Let equalize before reinstalling bolt.

 

[NMNeil]

Thanks. I just did an eyeball measurement and the oil level is about 1 3/4 inches below the bottom bolt, but the dipstick is still on the full mark.
I'm printing the gaskets at the moment so I won't have it back together until tomorrow, but it will be interesting to see if that's the problem.
I will file a new 'full' line on the dipstick though.

 

[HarryVanderpool]

Arms, jerking steadily are often caused by sticking valve(s) on your hyd pump.
Often, that condition will clear itself after heavy use and lift smoothly.
I did have to remove the pump years ago for that condition and found a scored guide pin.

 

[NMNeil]

I 3D printed a widget so I could see the oil flow volume with the top cover removed without it spraying everywhere, and the oil came out at a lethargic dribble.
I could see one of the pump housing gaskets leaking, so the pump will be coming out, but at least it gave me the opportunity to adjust the draft and position control using the Zane inspired 3D printed gauge rather than guesswork.

 

[Btzj02]

You need to post a picture of your 3D printed Zane thang.

 

[NMNeil]

It's not my design but freely available.
You will have to use your slicer to split it as it won't fit on most 3D printer beds.

Ford Tractor Hydraulic Adjustment Jig by Ulmeck | Download free STL model | Printables.com