air in day after i bleed

[patshorkey]

have ford 429
i drained hydralic from differential , changed filter . started and bleed lines at cylinder , at gannon box pitch cylinder , put about 1/2 gallon in jug . bleeding
works just fine that day . but the next day . box will not raise untill i bleed it again . this is happening day after day . many days in a row .
i am sure i have enough fluid in resavoir .
does any one have any ideas.
thanks

 

[J_J]

Look at your tank fluid and see if there is air bubbles. If so , then you may have a suction leak and are generating air bubbles, which can displace fluid in the cyl.

Another possibility is that the cyl is sucking air in through the rod seal.

If you cut off the tractor with the box raised, does it settle to the ground?

 

[patshorkey]

JJ
thanks , i will try and check it out later today ,

 

[patshorkey]

JJ
yes the box does fall to the ground.

 

[J_J]

Then if there is air in the box cyl only, then the rod seals are to blame, and you might not be able to fix it, and the seals are designed to keep fluid in. The load/weight could pull a vacuum and cause the cyl to suck in air.

There are other things to let a box fall such as leaking cyl, leaking valves, but if it is strictly air, you have your answer.

 

[wdchyd]

I'd check suction hose and connections and/or the pump shaft seal for air entrainment (sucking air)

JJ, you may have seen cyls sucking in air but this has not been my experience....not saying it can't happen, just not seen it....

any leaks I've experienced downstream of the pump usually leaks out, not in

is the pump loosing it's prime (shaft seal failure) or is the cyl just experiencing a lag time to go up....(air bubbles in cyl).......or maybe the cyl piston seals just need replacing (seals by-passing)

 

[J_J]

He never did reply about bubbles in the tank.

He probably has a combination of causes, however the cyl itself can be tested for integrity.

 

[patshorkey]

jj
thanks , sorry , I did not see reply and question .
the 1 1/4 plug is too far back to see any oil or air bubbles.
the side cover can not come off to look there , because it is below oil in case .

thanks

 

[J_J]

If you do have a suction leak, and can not see in tank/reservoir, then you can remove a hose and place in a bucket, push a lever and and check for bubbles.