John Deere 3020 Hydraulic Chatter

[shuff3]

I'm new the TBN so cut me some slack if I post this to the wrong page.

I have a John Deere 3020 s/n 081743 with the following hydraulic issues. Purchased used with several pre owners.

3020 Pressure Control Valve (priority valve)
Original came on machine R31624R
o Hydraulics extremely slow and weak
 10 sec or more to raise 3 point
 Remotes very slow
Spring in valve very weak
Installed R40559
o For 3010 s/n range -049,999
o Hydraulics at spec
o Extreme amount of chatter
 Spring in valve is very strong
Parts manual calls for a AR51732
o Subs are
 R40154
 AR40403
 AR40029
 RE13273

Does anyone have an idea what is causing the chatter?
Am I using the correct Priority Valve (Pressure control valve)

 

[Tx Jim]

Welcome to TBN
Has hyd filter been changed & hyd oil sump screen checked/cleaned????

I think you don't fully understand the function of the priority valve on the JD closed center hyd system. The priority valve is designed to close at about 1700 psi so that power steering/brakes have hyd pressure. Technically the hyd system will function without the priority valve in the hyd system. The stroke control valve in frt hd pump controls the pressure. Chattering can be caused by failure of trans pump to supply adequate amount of oil to front pump or internal hyd leaks in hyd system OR faulty inlet/outlet valves in frt hyd pump.

One needs to perform ""very good diagnostics"" on these closed center hyd systems before replacing ANY PARTS including hyd pumps.

 

[shuff3]

Thanks Tx Jim. I was leaning toward the supply pump. Will check the pressure when I get all the fittings. However, when I installed the priority valve my hydraulic performed great, only I got the chatter. I noticed yesterday, when I was getting ready to rake hay that the SCV did not chatter on start up when I raised the rake. My guess is colder oil. After haying season, I hope to start from the beginning and work my way through the system. The tech manual is very vague with information on the hydraulics - diagram not very helpful.

 

[Tx Jim]

Thanks Tx Jim. The tech manual is very vague with information on the hydraulics - diagram not very helpful.

You're welcome. Which TM are you referring to as vague? JD or I&T?

 

[shuff3]

Manual is an SM2038 for 3000 series tractors. Purchased from John Deere dealer here in Michigan.

 

[Tx Jim]

Manual is an SM2038 for 3000 series tractors. Purchased from John Deere dealer here in Michigan.

Didn't your SM contain the pages shown below with schematics & explanations? I suppose due to the fact I served as a JD dealer service manager for 13 yrs these pages are easier for me to comprehend.

 

[shuff3]

Yes, it does. But I'm looking for all the individual valves, and passages as well. Basically a hydraulic diagram. What I'm used to dealing with can be explained in the attached of our PC5500 shovel. This is an old diagram, but you can see nothing is left out.
View attachment PC5500 15027 Hydraulic Plan 934 984 40.pdf