JD HYDRAULIC PROBLEM

[kak]

I have a 2001 JD 4300 with a hydraulic valve malfunction. The 3-point hitch won't lower. How do I access the rear hydraulic valve to remove and replace it?

[Redneck in training]

Originally Posted by kak

I have a 2001 JD 4300 with a hydraulic valve malfunction. The 3-point hitch won't lower. How do I access the rear hydraulic valve to remove and replace it?

Check the down speed adjustment knob first. If it is closed 3 point will not go down.

[kennyd]

Welcome to TBN

As mentioned, hopefully the rate-of-drop valve is closed-it's the knob under the seat. If that is not the problem, then it could need to be removed and cleaned-there was some problem in some models with this.

[kak]

Originally Posted by Redneck in training

Check the down speed adjustment knob first. If it is closed 3 point will not go down.

The rate-of-drop adjustment knob is completely opened...something is broken or stuck. How do I get to the "offending" valve?

[kennyd]

Take a look at THIS post, and the attached picture below.

[kak]

Originally Posted by kennyd

Take a look at THIS post, and the attached picture below.

Thanks for the info. We managed to get to the part numbered "9" on the schematic and to remove it successfully. It looks fine and I am not sure what to do next...the goal is to restore the function of the 3-point hitch.

[kennyd]

Just clean everything good, something in that valve is blocking the return flow from the 3PH piston. Have you tried lowering it with the valve removed? Be careful though as fluid may shoot out-as well as whatever is blocking it.

If this does not solve your problem, then you may have a more serious problem either the rockshaft valve or the piston assembly itself.

This may be a good time to invest in a FSM (Factory Service Manual) on CD that sells for under $100.

[dfkrug]

Originally Posted by kak

Thanks for the info. We managed to get to the part numbered "9" on the schematic and to remove it successfully. It looks fine and I am not sure what to do next...the goal is to restore the function of the 3-point hitch.

Your prob is very likely with the position control valve to the left of the
rate-of-drop valve.

There is an inline filter built into the fitting in the hardline that goes between
the SCVs and the position control valve. The service manual says you have
to open up the valve an clean it out if this small metal mesh filter fails. Mine
has failed....I can look inside and see the mesh has opened up. I will be
posting pix of inside this valve when I get my engine back together.

As Kenny says, get the service manual. You can get the CD for $40 from
a dealer on eBay.

[kak]

Thanks a million! Taking the "spool" out and manually raising the 3ph arms squirt out some hydraulic fluid. Reassembly was easy and the 3ph now works normally. What can be done to prevent this from happening again? (It is a lot of work to have to do and I'd like to avoid it if possible.)

[dfkrug]

Originally Posted by kak

What can be done to prevent this from happening again?

I think JD knows that the position control valve is very sensitive to fluid
contaminants. Otherwise, why put an in-line filter between the SCVs and
this valve? Other tractors I have had don't do this. If you get the
factory power beyond kit to power a backhoe, they include a larger in-line
fluid filter when you replace the PB hardline.

Did you look to see if your filter is compromised? At least you did not have
to remove the rockshaft assembly, which is very heavy.