4720 Power Steering has hard spots when turning quickly

[Brown Dog]

I hadn't tried rpm over 2,000 so idk.

The steering gets tight then easy while turning.

It works fine if your not in a hurray lol

 

[oldnslo]

Getting tight then easy again points towards lack of flow from pump. Since steering units are typically buried and hard to access installing any type of diagnostic equipment is a real PITA.

An experiment I would try:

Turn the steering wheel at slowly increasing speeds lock to lock with engine at a constant RPM. I.e. 10 RPM, 15 RPM, etc. until point of failure. Increase engine RPM's and run same experiment. If flow related, the point of failure should be with higher steering wheel RPM's with increased engine RPM's.

I know on my Branson at lower engine RPM's it is fairly easy to try and steer faster than pump flow will allow.

 

[arlen4720]

I'm in 2wd.
Where does this line with filter, go into the trans ?
I hadn't had time to diagnose.

That's the filter I was talking about. It shows it in the operator manual. I can't remember what side it's on. I will look when I do chores tonite.

Edit: It is on the left side, below the brake pedals. It's just a silver fitting inline, maybe 1.5 inches in diameter and maybe 3 inches long.

After looking at the hydraulic schematic, I don't think the filter is your problem, if it were plugged you would be having tranny problems too. See Item "X" on page 992
Do you have a spinner on your steering wheel by any chance?

 

[Brown Dog]

I hadn't had time to check into this problem yet :-(
I do NOT have a spinner on steering wheel.

 

[Brown Dog]

and don't forget about the filter on the high pressure side of the power steering pump ...

Bingo, you were right :-D
The inline filter under left floorboard was stopped slam up.
I cleaned it & the pickup screen in bottom of trans, replaced $pin on Hyd filter ($60) & Hy-Gard fluid.
Works like a Champ now.
Hard to believe that inline filter was stopped up with only 230hrs on this gently used machine.

 

[chevy]

If I turn wheel slowly, it's ok.
But turning quickly - it has hard spots in it.
Can the pump have air in system OR can the pressure or volume be increased ?

I'm running throttle at 2,000 rpm's, because I'm Mowing in E-PTO setting.

Specs shows this 4720 P/S to have more flow than my older 4700, but the 4700 doesn't do this.

Any ideas ?

Lube the universal joint in the steering column.

 

[Brown Dog]

The problem was restricted fluid flow, not a binding concern.
Cleaning the inline filter Fixed the problem.

 

[Furu]

Bingo, you were right :-D
The inline filter under left floorboard was stopped slam up.
I cleaned it & the pickup screen in bottom of trans, replaced $pin on Hyd filter ($60) & Hy-Gard fluid.
Works like a Champ now.
Hard to believe that inline filter was stopped up with only 230hrs on this gently used machine.

When I did my 400 hydraulic service I cleaned that filter even though the service interval said it was not necessary. Seemed clean but do not understand why JD does not have you clean it at the 400 hour service. Your 230 hours is really odd however.
Glad the problem had been resolved for you.

 

[sunnyside360]

Just recently cleaned that same screen/filter on my 4320 for the 400 hr service and it wasn't very dirty at all. Begs the question why some are clean while others are dirty especially for gently used machines which is the category I'd put mine in. Also, have cleaned the same screen on my 3720 a few times and it is always fairly clean. Guess it's better to be safe than sorry.

 

[Brown Dog]

If no problems occur when steering quickly, then the inline filter probably doesn't need cleaning
Is my guess.