John Deere 855 intermitant hydrolic problem

[sampwell]

Hi every one, im new here
Im french canadian and not very good in english sorry if you dont understand me lol.

I have a john deere 855 1987.

My problem is intermitant with the FEL, is a FEL homemade i have fit.

first one is, the right fonction and the regen when full right, have a intermitant delay, the cylinder travel half of is stroke then stop few
second, then continu, but if i use it 1-2 times it will work like normal, after dump, drive a little the problem back for the 1-2 use....

second problem for raise the FEL, intermitant too, i need to old the SCV few second before it go up, some time it jerk like air in the line. And in the half way its same jerk and stop raise few second.

the 3 point work perfects, steering works perfect, transmission works perfect. i try to replace transmission filter, check the hydrolic oil to be at perfect level with john deere oil.

Can someone help me?
thanks

 

[CoyPatton]

Just taking a wild guess here, but I suspect your 855 does not have sufficient flow to operate what you have installed.
Your 855 in round numbers has about 5gpm (US gallon) flow rate. Valves and hose size need to match.
A second wild guess would be related to where you pick up your pressure to the loader and the return to tank plumbing.

In its simplest form, hydraulics are a continuous loop from the tank through suction lines, to the pump, to hydraulic fluid usage to the tank.

Also be certain that after filling your cylinders and lines for the added loader that you are full of fluid. Generally this would be tractor on level ground, and bucket flat or fully curled loader in lowered position. If you are not near full at this setup, personally I would about 1/3 or a bit more dump my bucket and lift the loader to about 3’ off the ground with a level bucket, then check fluid level and fill to about 2/3’s to 3/4’s of the distance between add and full on the dip stick.

 

[sampwell]

I have 1/2 inch rubber hose and 3/8 inch metal hose to cylinder.
the tilt cylinder is 2 inch bore.
for raise i think its 2.5inch bore.

i use the original scv and line

 

[CoyPatton]

I have 1/2 inch rubber hose and 3/8 inch metal hose to cylinder.
the tilt cylinder is 2 inch bore.
for raise i think its 2.5inch bore.

i use the original scv and line

Mine is a Koyer loader and it was on the tractor when I bought it. I do not claim to be a hydraulics expert, and you may want to ask your question in that area. But I would guess that the metal lines on my loader are 1/4” at the largest. And the only rubber hoses that large (may be 3/8”—not sure with out checking) are the supply and return main hoses to the control valve. Also my cylinders I think would be 1.5” or perhaps 1.75”.
I can tell you that as you operate your SCV it restricts the flow (goes from a larger diameter to a smaller diameter) and increases pressure. Then as you go to larger hoses 3/8” and 1/2”, you decrease pressure.

I really suggest a series of photos with a description of size of lines and cylinders associated with the photos over in the hydraulics section in this forum.

FYI: tractordata.com list your hydraulic flow at 5.6 gal per minute. If you have power steering you can split that just about down the middle to get your working hydraulic flow.