4720 Power Steering Intermittently Locks Up

[bam747]

The power steering on my 4720 has a very, and I do mean very, intermittent problem where it will essentially lock up.

By "lock up", I mean everything had been working fine and then suddenly the steering wheel will freeze up. It has done this with the wheels straight ahead or strongly turned. It has done it in cold weather, warm weather, shortly after starting the tractor, and after hours or days of continuous use with nary a hint of a power steering issue.

When my tractor does exhibit this problem, it has always cleared itself up after cranking on the steering wheel for a minute, and then I never see the problem again that day.

I cannot reiterate just how intermittent this problem is, which is actually more frustrating that if the steering would have just permanently locked up.

I currently have the tractor at a local JD dealer's service department. They've had the tractor for two weeks, but of course they cannot replicate the problem. To the service managers credit, he did do a search in JD's service advisory system and DID find some reports of power steering problems with some possible diagnostic tests to run. Still, they have no idea what to fix at this time.

Has anyone else out there experienced this problem with their 4000 Twenty series tractor? If so, have you found a solution?

 

[Furu]

I also have a 4720. I have never seen anything like what you describe.
What year build do you have? Early or more recent? Is there any type of work that you are doing that might be related or has it happened in varied types of activity?

 

[bam747]

I also have a 4720. I have never seen anything like what you describe.
What year build do you have? Early or more recent? Is there any type of work that you are doing that might be related or has it happened in varied types of activity?

It's a 2007. Open station. It only has about 300 hours on it. 'Course, that means it is long out of warranty.

In retrospect, this problems seems to occur when doing lots of lock to lock steering wheel maneuvering while using the FEL. Note however that the bucket is generally empty and I'm not calling for any other hydraulic functions at the same time (i.e. not raising/lowering/dumping/curling the FEL or raising/lowering the 3PH rear blade nor performing any hydraulic angling/offsetting/tilting of the blade). 4WD is generally engaged when this happens. I generally see the problem in colder weather plowing snow, but just recently saw it in normal spring temperatures as well.

 

[jd110]

What size front tires are you running? Does it seem to happen if in soft ground? I had a customer some years back that was running extra wide tires on his 870 with duals on the rear. It would act the same way. We replaced steering valve, cylinder and raised relief valve in attempts to make it perform better, but the tires were just too much friction on the ground in certain operating conditions.

 

[bam747]

What size front tires are you running? Does it seem to happen if in soft ground? I had a customer some years back that was running extra wide tires on his 870 with duals on the rear. It would act the same way. We replaced steering valve, cylinder and raised relief valve in attempts to make it perform better, but the tires were just too much friction on the ground in certain operating conditions.

Standard factory R4 tires front (10.00-16.5) and rear (17.5L-24).
Hard ground and asphalt (generally with snow and ice on it, so "slickery").

Neither myself or the JD dealer want to just start replacing parts and hoping we find the problem, especially since 95+ percent of the time there is no issue.

Like I said, this is one of those very frustrating, and the very definition of an intermittent, and generally non reproducible problems, at least given my ultra low hour and infrequent usage of my tractor.

 

[Rockgod]

The only problem I ever had with my 4320 was a steering problem. Only I had the opposite issue, loose steering. When ever I'd go down the road in A range the problem would show up. The tractor would actually drift into the other lane. Turns out the steering cylinder/ram had an internal leak. They replaced it and everything was fine.

 

[sunnyside360]

I have a 2010 4320 open station which I bought new in February 2010. I experienced the exact same issue you described. It only occurred with mine with a very heavy load in the bucket of FEL. Someone here on TBN (kennyd iirc) said rear weight ballast was needed to in effect get less weight on the front wheels and allow the power steering to work (power steering relief valve tripping?). So I got a ballast box to use with the FEL and I haven't experienced the problem since. That was about 2 years ago.

Are you using the FEL when this happens? If yes, I suspect this is the same issue I had.

 

[bam747]

I have a 2010 4320 open station which I bought new in February 2010. I experienced the exact same issue you described. It only occurred with mine with a very heavy load in the bucket of FEL. Someone here on TBN (kennyd iirc) said rear weight ballast was needed to in effect get less weight on the front wheels and allow the power steering to work (power steering relief valve tripping?). So I got a ballast box to use with the FEL and I haven't experienced the problem since. That was about 2 years ago.

Are you using the FEL when this happens? If yes, I suspect this is the same issue I had.

Hummm...

Unfortunately, my lockup is occurring with and empty bucket. I cannot recall it ever happening to me with a heavy load on the FEL.

As for ballast, I have my Land Pride RBT3596 on the 3PH of the tractor at all times. It weighs around 1,000 lbs, and the blade hangs a good 4' out past the end of the lift arms on the 3PH. This provides a lot of counter balance on/around the rear axle. I also have two 110 lb JD cast iron weights on each rear wheel, or another 440 lbs of ballast centered on the rear axle. I also carry another 350+ lbs of, um, "ballast" over the rear axle when I'm sitting in the seat (yes, I'm the very definition of "big and tall" also being 6' 6" ).

My rig is pretty well ballasted for the FEL, excluding loading the rear tires. In my use so far, my blasting is working very well, even when I have a full load of heavy sand in the bucket. I've never come close to lifting a rear wheel off the ground, even when maxing out the FEL lift when digging a full bucket of dirt/sand out of a pile.

I do appreciate the lead on the "power steering relief valve" though. I will mention it to my service rep at the dealer.

Thanks!

Just for grins, here is a photo of me and my 4720 loading full buckets of sand into a full size tandem axle dump truck during a recent project to replace all the sand in an indoor arena. And no, the rig never exhibited the power steering lock up issue at all during the entire multi-day project.

 

[sunnyside360]

The cause of your steering lockup is completely different from mine but yours is likely in the power steering circuit. Those very intermittent problems are usually difficult to diagnose. Good luck.

 

[charleyfarmall]

Check your trans/ hydraulic fluid level. I don't think it is actually locking up. It's the pump momentarily not delivering pressurized fluid to the steering either from sucking a little air through it or for some other reason. The steering gets impossibly stiff when that happens.