8N Hydraulics - will not lift after mowing with bush hog

[john6082]

I have a 1952 8N. While running in neutral, hydraulics work fairly quickly and smoothly with bush hog attached. I can raise and lower the bush hog without any problem. Pump seems strong. After 30 minutes with bush hog raised, the bush hog will drift down a couple inches. However, while mowing with bush hog down, it will not raise up immediately, I have to wait about 5 minutes for it to raise. Took the right inspection plate off. There was no indication of oil leaking out of the ram cylinder. Anybody have any ideas, thanks.

 

[Bruce(OR)]

Fluid is how old/condition/level?

 

[john6082]

the fluid that was in it was clean, no water. I changed it the other day with Napa 134 mineral oil 90W. no change

 

[TheOldHokie]

I have a 1952 8N. While running in neutral, hydraulics work fairly quickly and smoothly with bush hog attached. I can raise and lower the bush hog without any problem. Pump seems strong. After 30 minutes with bush hog raised, the bush hog will drift down a couple inches. However, while mowing with bush hog down, it will not raise up immediately, I have to wait about 5 minutes for it to raise. Took the right inspection plate off. There was no indication of oil leaking out of the ram cylinder. Anybody have any ideas, thanks.

Leak down after getting oil hot is probably mild leakage from the lift piston. Not partucularly unususl on these old tractors.

I dont understand the wait 5 minutes part. Is this only when actually mowing or is it something thst happens after just running for a while?

And just FYI you do not have "134" oil in the tractor. You have conventional SAE 90 GL1 gear oil in it.

TOH

 

[Eman85]

So when you start the tractor and place it in neutral with the PTO engaged the lift works fine? 30 mins with the bush hog raised is that with the tractor shut off that it stays for 30 mins and drop a couple of inches? Thern when mowing you attempt to raise the bush hog and it won't move up at all until 5 mins later? When you looked in the rt. inspection plate was that with the bush hog raised and the tractor off? Is the fluid at the correct level?

 

[john6082]

The five minutes is usually after mowing. It only happens when mowing. The tractor was on for 30 minutes. The tractor was on and different positions. However, the hydraulics work normally while inspecting. Fluid at correct level.

 

[Eman85]

So with the tractor running, the PTO engaged and the bush hog raised the bushog will drop?
Start the tractor and raise the bush hog then shut the tractor off with the bush hog at it's highest level, what happens? With it up and the tractor off remove the inspection cover and see if the piston is leaking.