JD4020 Hydraulic issues

[sycamoreview]

Hey Forum,

I just bought my first JD and its a 1964 4020, but I knew about a small issue with the hydraulics that helped on pricing..
So when I test drove, the steering would bind and lock up bit time, like no turning at all when trying to turn left, but not when turning right. Now when owning it for a day, I notice more things. Steering the same, spotty, sometimes it turns quick, other times I move the wheel, and the steering catches up a few seconds later, then 10 seconds pass, its fine and fast. I do hear the pump/steering valve, something under the dash console, whine and then it goes a way, or comes back. Goes away when the steering plays nice, loud when steering is binding. To be plain, its spotty..

Something else I noticed tonight, the 3 point lift arms, they chatter and come up slow, or extremely slow almost not moving, then they come up fast near the top.
So first thing when looking at all this, I topped the oil off, low by 7 gallons.. guy mentioned he'd blow lines off sometimes when bailing hay, so maybe thats why it was so low.. but anywho, more fluid didnt help a ton, it did a little but not much. I have not tried the remotes, not sure if they are just as sluggish, but ill try tomorrow when there is light.


I know the obvious from reading around, I should dump all the fluid and clean the screen (or replace?), and if there are other filters too. If the problem still persists, what else should I do before going straight to replacing the pump? I want to make sure I am doing the small things and troubleshooting before just doing a pump that might not be broken.

 

[Tx Jim]

Over my many years associated with repairing tractors I've read/heard of many tractors having hyd pump replaced without proper diagnostic procedures being performed to determine that replaced hyd pump was in fact still good! Before replacing any hyd pumps one should perform good hyd diagnostic procedures.

As you stated first procedure should be to change hyd filter & check/clean hyd oil suction screen. Screen retainer plug is encircled in orange circle. I also suggest to check hyd stand-by pressure by attaching a gauge to breakaway coupler then move control lever to pressurize the gauge which should be 2250 psi. I'll guess steering problem is faulty seals on piston in steering motor under fuel tank. These seals can be replaced by supported tractor & removing a side frame to access retaining plugs & spindle. https://partscatalog.deere.com/jdrc/sidebyside/equipment/8481/referrer/navigation/pgId/8136340

 

[buickanddeere]

Tim S rebuilds a lot of tired power steering valves . To better than new . That is one possibility.

 

[sycamoreview]

I'll do what was recommended fluids and filters and check. Its gotta be something because I ran for an hour driving it just to learn the machine and see if it'd work any air out. The sluggish lift arms that'd chatter with the noise under the dash makes me think the hydraulic pump is starving for fluid thats not getting there fast enough... something odd for sure, but this should be fun to figure out.

 

[sycamoreview]

Is it fine to use ISO 46 oil for the Hydraulic fluid ?

 

[Jim.ME]

Is it fine to use ISO 46 oil for the Hydraulic fluid ?

NO.

You need JD Hy Gard or a UTHF meeting the John Deere J20C specifications.

 

[Scott 730]

If the problem still persists, what else should I do before going straight to replacing the pump?

Always, always, always, do proper diagnostics before replacing parts. Untold amounts of JD main pumps have been replaced only to find out that the pump was not the problem. Invest in an operators manual and a service manual before attempting backyard repairs.

 

[trackrat]

I use iso 46 hyd oil in all my older equipment it is just a heaver wt of oil

 

[Jim.ME]

I use iso 46 hyd oil in all my older equipment it is just a heaver wt of oil

Maybe you run ISO 46 in your JDs with wet clutches or brakes without failures, but many have tried and paid the price for saving a buck. I would not advise anyone to use it in their tractor where a wet brake/clutch fluid is specified. ISO 46 hydraulic oil is not an approved wet brake/clutch fluid which is needed for his 4020. JD Special Purpose 303 oil was the original spec'd oil. That is no longer available the current product is Hy Gard if you get it from JD. Aftermarket it is a UTHF that meets the J20C spec.

 

[sycamoreview]

I think someone might have topped it off with ISO 46 for me the other day.. ill deff dump all the fluid and use Hy Gard or J20C Spec.

 

[miangus]

If it is a SyncRo range oil is not pumped to the front rotary pump when the clutch pedal is depressed.

 

[buickanddeere]

I use iso 46 hyd oil in all my older equipment it is just a heaver wt of oil

Is this ISO 46 oil rated for wet clutches and wet brakes ?

 

[sycamoreview]

Well this fell behind apologies, I only recently got to servicing all fluids. It didn't change anything. Screen was pure clean, and filter didn't look that bad. Pump still chatters here and there, and under the dash the same.. What's next to look for?

 

[trackrat]

Is this ISO 46 oil rated for wet clutches and wet brakes ?

no its not sorry I just don't use in powershift tractors the only thing my tractors have is wet brakes

 

[Jim.ME]

no its not sorry I just don't use in powershift tractors the only thing my tractors have is wet brakes

Wet brakes should not be running in ISO46 hydraulic oil.

 

[sycamoreview]

Hey any ideas what I should try next before replacing front steering seals? If not, ill just proceed with doing front seals,

 

[Tx Jim]

I suggest to get a 5000 psi gauge & attach a JD male hyd tip similar to tip in photo below. Then insert male tip in each rear breakaway coupler then move handle under breakaway 90°. With engine operating at idle speed move scv lever correct direction to pressurize the gauge. Pressure reading should be 2250-23350 psi.

 

[sycamoreview]

I will do,

 

[buickanddeere]

I suggest to get a 5000 psi gauge & attach a JD male hyd tip similar to tip in photo below. Then insert male tip in each rear breakaway coupler then move handle under breakaway 90°. With engine operating at idle speed move scv lever correct direction to pressurize the gauge. Pressure reading should be 2250-23350 psi.

is as much pressure as a sea depth of 52472 feet

 

[620 John]

Is this a syncro range transmission??? If so how do the hydraulic functions respond with the clutch pedal depressed???

Pressure checks are a good starting point, BUT a bad pump can still build pressure. They only way to actually check the main hydraulic pump is to disconnect the high pressure main supply line connecting to the priority valve and plumbing into a flow rater. This involves a lot of mickey mouse work trying to move the line out of the way enough and find the right fittings to make it work with a flow rater.