Ford 40 series heavy power steering

[JohnDeere8530]

Have an ageing Ford 6640 SL with suddenly heavy steering. As far as I know all external filters have been changed on the backend, but this made no difference. Where should I next look at ?

Thanks in advance

 

[Lincsman]

Not much help, but somewhere there will be a priority valve stuck and not letting oil through properly.

 

[forblue]

Depends on what type of hyd pump system 2 pumps or ccls, if you have 2 do a pressure check on steering axle hose's, again 2 w/d or 4, 2 is 2100psi 4 is 2500psi, prv is in orbital steering unit

 

[farmerm]

Is it far different to the 6610? Power steering has its own oil reservoir and filter at the front end of the tractor.

 

[Lincsman]

Is it far different to the 6610? Power steering has its own oil reservoir and filter at the front end of the tractor.

Very different, no dedicated pump, hence priority valves.

 

[JohnDeere8530]

many thanks for this.. I believe there to be only one pump and everthing else works ok, so guess the priority valve in the orbital unit ?

 

[Fruity]

The steering on my 7840 went suddenly heavy a few years ago, I can’t remember why but I gave the steering wheel a sharp tug upwards and it freed up again! Worth a try?

 

[forblue]

That is why i suggested getting a pressure check done i have had two 40 series where the bearing seized in in top of steering column., if you have a ccls pump [ one large and two smaller filters on right under cab, that has three pumps hyd,l/p,and steering all in one, if you have two pumps one mounted front left on engine the other on right under cab that is a tandem pump hyd and steering so each system will have a steering pump , the orbital motor has only a prv and not priority, layout on here..

 

[JohnDeere8530]

prob solved, gave the steering wheel a hard pull up and now works fine. Many thanks for the replies