4520 power steering problem

[cdaledave89]

I have a 2009 4520 w/ about 110 hours and noticed a problem last night with, what I think, is the power steering system. After parking in the barn and while still idling, I could feel "hammering" or "bumping" in the steering wheel. I left it running and got out to check around the tractor. I traced the hyd lines from the PS cylinder to the right side of the tractor and I put my hand on the hard piped hyd line that is vertical and is closest to the cab. I could feel the "hammering" or "pulsing" in the line. Totally random. It feels like when you close a hyd valve and the pipe or hose shudders. Except I'm not turning the wheel or putting any load on the PS system at all.

I did a search on here last night and read about the instances where the fittings were loose at the cylinder and air was getting into the system. "That must be it!", I said and ran to the barn to check the fittings. I checked the tightness of all of the PS hyd line fittings that I could reach (with the exception of the ones that go into a block right in front of the cab and below the steering wheel). They were all tight. So I started the tractor again and checked it. It didn't do it at first, but after idling for a few minutes, it started "hammering" again.

Any idea what it could be?

 

[Red Horse]

I have a 2009 4520 w/ about 110 hours and noticed a problem last night with, what I think, is the power steering system. After parking in the barn and while still idling, I could feel "hammering" or "bumping" in the steering wheel. I left it running and got out to check around the tractor. I traced the hyd lines from the PS cylinder to the right side of the tractor and I put my hand on the hard piped hyd line that is vertical and is closest to the cab. I could feel the "hammering" or "pulsing" in the line. Totally random. It feels like when you close a hyd valve and the pipe or hose shudders. Except I'm not turning the wheel or putting any load on the PS system at all.

I did a search on here last night and read about the instances where the fittings were loose at the cylinder and air was getting into the system. "That must be it!", I said and ran to the barn to check the fittings. I checked the tightness of all of the PS hyd line fittings that I could reach (with the exception of the ones that go into a block right in front of the cab and below the steering wheel). They were all tight. So I started the tractor again and checked it. It didn't do it at first, but after idling for a few minutes, it started "hammering" again.

Any idea what it could be?

I imagine you have not noticed any leaks so your fluid reservoir is not low? Did you check the fittings on the hydraulic cylinder? those things are exposed and I could easily see a branch making contact and putting a restriction in.

As for air, I had two of the hoses disconnected recently do modify the parking brake control and had no "air bound"issue so can't imagine that is the cause.

 

[cdaledave89]

Yeah, I checked the fluid. It's right where it should be.

It's out of warranty so I'm gonna try to figure it out myself. If it gets worse or persists, I'll have to give in and call the dealer.

 

[AKfish]

Your problem appears to be very similar to mine. The steering on my 110TLB has "chattered and chirped" along with a pulsing, almost irratic jump in the front tires for several years, now. Basically, since the tractor was new.

Still does it... I considered taking it into the dealer for testing and repair - but it's never leaked or stopped working and it's never gotten any worse.

Since it's not a leaky steering cylinder or any of the hoses; and the hyd pumps are all straight - no failures, etc. - I'm convinced that the problem is with the steering motor. It's located at the base of the steering column next to the fuse box within the instrument cluster, etc.

I'm not gonna do anything until it just stops working or the steering function gets so weak that I'll be forced to take care of the problem!

Not a real solution at all... I realize! But, it's not really "broke", either. So, if it ain't broke - don't fix it! Just yet...

My $0.02

AKfish

It may be some residual air in the system of your 4520 from the recent hyd line disconnect. Keep using the tractor (as you've said) and see if the situation doesn't resolve itself.

 

[Trainpilot]

Your problem appears to be very similar to mine. The steering on my 110TLB has "chattered and chirped" along with a pulsing, almost irratic jump in the front tires for several years, now. Basically, since the tractor was new.

Still does it... I considered taking it into the dealer for testing and repair - but it's never leaked or stopped working and it's never gotten any worse.

Since it's not a leaky steering cylinder or any of the hoses; and the hyd pumps are all straight - no failures, etc. - I'm convinced that the problem is with the steering motor. It's located at the base of the steering column next to the fuse box within the instrument cluster, etc.

I'm not gonna do anything until it just stops working or the steering function gets so weak that I'll be forced to take care of the problem!

Not a real solution at all... I realize! But, it's not really "broke", either. So, if it ain't broke - don't fix it! Just yet...

My $0.02

AKfish

It may be some residual air in the system of your 4520 from the recent hyd line disconnect. Keep using the tractor (as you've said) and see if the situation doesn't resolve itself.

If the 3320 has the same hydraulic system as the 4520, I have some answers. Our 4520 has a 2 circuit hydraulic pump, which is fed from a cast iron manifold that connects to the top of the pump with an o-ring for each section. This is fed from the sump. The rear circuit on our tractor feeds the steering and the hydraulics for the clutch/shuttle circuit. The rear o-ring leaks air under suction. Air into the hydraulic pump can cause chattering, surging, and noise. Too much air, it loses prime and doesn't operate. A plugged strainer might increase the tendency for this to occur. I have fought this problem on two previous occasions and am facing it again. This time I may try to machine the manifold so that the rear o-ring is pushed more tightly agains the housings. I'll post results soon. There should be some kind of TSB and fix for this problem if it is common. Next time this happens, listen carefully at the hydraulic pump immediately upon shutdown. On ours, I could hear the air slurping through the fitting. I tried filters and cleaning strainer, and also the low-vis fluid, but it's a problem with the seals. The good news is that these can be replaced without draining the system or significant leakage.