JD 70a FEL slow to raise

[croasdale]

My 70a FEL (on a recently acquired early 90's JD 955) does everything fine except it's often (not always) slow to raise. I have to pump the lever which will make it raise a little further (this is with nothing in the bucket) and then it slows to a stop again. Increasing engine RPMS helps some but it still won't lift like it should. This problem is intermittent but occurs more than half the time. Other times it lifts (even with a load) pretty well.
I didn't get a manual for the 70a so don't know where things are like the drain plugs and filter and screen(s).
Any help in diagnosing the problem would be appreciated.

 

[zzvyb6]

If you have quick disconnects on that loader and an extra 2 way cylinder or hydraulic motor, plumb the cylinder into the circuit and see if its the supply/valve or a plugged or pinched hose or air in the line.

 

[dfkrug]

I didn't get a manual for the 70a so don't know where things are like the drain plugs and filter and screen(s).

You need to get the 7/8/955 factory service manual (TM1360) and operator's
manual. You can often find them used on Ebay. I did. The PDF version
of the service manual will save a lot of $ over the paper version. The
I & T manual is cheap, but not very good.

The only hyd filter is under the middle of the tractor, betw the frame
rails, next to the mid-PTO. Dirty fluid could be the problem.

The loader uses tiny 1/4 in hoses and has very easily dentable hard lines
on the loader cross tube. There are also flow-reducing fittings betw the
loader hoses and the cyls. Crud in there would be very bad.

 

[dogbreath108]

You might want to try a test..
With the bucket raised, tractor off, how fast will it drop?? With, without weight in the bucket. Then work the valve much like you would when you try to deal with the problem. Does it change the drop rate?

You might have a loose or floating free soft piece (oring, seal or whatever) in your lift spool (valve).

Joe