Hydrostatic Power steering problem

[DFZ]

We have a Danfoss power steering motor on our FORD 4630 that we have started to have problems with. I post this question here because the same type of hydrostatic power steering system that is used on all brands.

The problem is the steering has started to wander and will not hold course, most often returning to center as i drive along. So in a left hand turn i have to constantly turn left to keep wheels turned. Also there is no longer any steering stop on the system. I can turn the wheel all day left/right and it will not come up to a stop/pressure relief.

At first I thought something must be wrong in the steering motor, so we went through it and re-sealed it, expecting to find something blown or broken spring. We did not find anything.

So my question is, could low pump pressure or bypassing steering cylinder cause this? I would not think steering cylinder issue because I cannot immagine that it could bypass enough that it would still not come up to a stop when steering full left/right. Could it be a pump issue? Or is the steering motor just worn out that would not show any visable problems?

Thanks.

 

[wore out]

(quoted from post at 15:32:46 10/02/23)

I would say it's likely that the steering cylinder has an internal leak past the piston seal(s).

Cap the lines going to the cylinder and see if that more or less locks the steering valve.

If you can still turn the steering wheel as before your valve is ''bad''.

 

[Blackhole49]

Our 85 555 backhoe at work used to do that as it got older. It became much more pronounced when it
was low on fluid. Being a small city, we drove the machine to all our job sites. When I retired in
2011, none of the steering components had been replaced.

 

[DFZ]

Thanks for the push to test the steering cylinder. It was bad and the piston seal was shot.

I would not have thought it could by-pass enough oil fast enough that it would prevent the wheel from coming up to a stop.

 

[wore out]

(quoted from post at 17:06:18 10/03/23) Thanks for the push to test the steering cylinder. It was bad and the piston seal was shot.

I would not have thought it could by-pass enough oil fast enough that it would prevent the wheel from coming up to a stop.

Glad to hear you have it solved.

Sometimes we blindly focus on one part or another and it takes input from an outsider to try something else.