D7 17A hydraulic blade will not hold itself up. I put a whole gallon of oil in it today , thought that might be problem, but no. It will raise, as soon as you let off on the raise control it goes down about as quick as it went up

Maybe the valve hydrolic is working bad or the packing seal are worn in cylinder

gemdozer wrote:

Maybe the valve hydrolic is working bad or the packing seal are worn in cylinder
I agree Hector. I myself have had a couple with bad cylinders is all. Holt and my number one wrench man did find a broken valve spring in a 143 pump once, that cost me $, as I would not listen (me?never ha ha) and had him strip pump and sent out. Nice to know I have a good pump still. JM
 

When you first start it lift the blade and then but your hand on the barrel of the ram. If the oil is by passing the packing in the ram it will create friction and that makes heat. So you should fill it warming under your hand if it is all leaking around the packing.

If not the ram leaking internally, then it is the control valve.

Ray54 wrote:

When you first start it lift the blade and then but your hand on the barrel of the ram. If the oil is by passing the packing in the ram it will create friction and that makes heat. So you should fill it warming under your hand if it is all leaking around the packing.
*** I followed the repair bible and everything pointed to bad poppet, pump issues; what I should have done was follow Ray’s advice about the heat/bypassing. Darned batteries were dead on my infrared gun, couldn’t tell by feel.
good luck on your repair.

If not the ram leaking internally, then it is the control valve.

it can only be 3 things.
the pump valve body is shot and needs rebuild you would also rebuild the pump itself at the same time.

the piston seals are gone so rebuild the rams.

the diverter valve if fitted is worn only choice is sleeve the valve body and make a new spool as part is no longer available. or simply make a connector block this can only be done if you dont have rippers or a hydraulic adjust blade.

Need to determine if the problem is in the cylinders or the Hydraulic Control.
Cylinders can be worn piston rings or end of travel relief valve problems.
Hydraulic control can be worn control valve, pressure relief valve problem or make up valves not seating.
That's if the unit is using the #46 hydraulic control.
 

I tryedto check for friction heat on the cylinders, did not feel anything out of ordinary, cylinders do leak a little at rod end ( packing) left cylinder seemed to be making a noise ... like a slight squealing type of noise . That's all I have so far thanks all

My post topic should read hydraulic blade will not stay up

If you suspect the pump, rig up a pressure check (blank flange a hose). These have been known to break a pressure relief valve spring.