7710 Ford priority valve

Does the priority valve on a 7710 Ford have anything to do with the rear lift?

On my 7710 II cab tractor ASC knob down 3 point and remotes knob up remotes only.

There is no priority valve as such.... There is a priority valve pack which contains an unloading valve which unloads the main pump flow, a
feathering valve that regulates the three point hitch and a combining/sequencing valve which senses remote circuit demand, combines the
main and auxiliary pump flows and provides remote circuit relief and auxiliary pump relief functions.

That valve pack is the epicenter of that hydraulic system as everything passes through there. I don't know what page in the parts book you
were looking at earlier.

Generally the most common problem in there is dirt on the seat of the relief of the combining/sequencing valve. Any time I've had that
apart I've always scribed the set screw and then counted the turns out... clean the valve and reinstall. If you've changed the spring or
seat that may require some trial and error to get it set correctly again but I'd use the original setting as a guide.

Rod

I have had it apart. The remotes stopped working and I took it apart and cleaned the valves. put it back together and it worked maybe three times and it quit. Tore it back apart and noticed the plug in the spool valve and took it out and when I put it back together it broke the seat that holds the ball bearing. Got a new seat and put it in lift and remotes worked good about half the day and then the lift stuck up and remotes quit I pecked around on the valve with a hammer in the field and the lift came down but would not raise again and the remotes worked spotty. I know that valve worked the remotes but was uncertain if it worked the lift.

I have not got a manual that talks about that valve good. When I got the seat for it I also got a screen/filter for it listed here as number 24. http://partstore.agriculture.newholland.com/us/parts-search.html?csid=88fa1f42e29c8f79b2f0eae076d75356&sl=EN&currency=#epc::mr60574ar323922bi3519285-33

I keep getting junk out of the valve every time I clean it. Why don't the filter on the pump catch it? Do you know were to put the filter/screen I got from new holland?

the filter is on the suction side of the pumps, a bad pump could put junk out.

The junk I get is some metal and the other stuff looks like hardened o-ring or plastic and you can break it with you finger nail.
If it was a pump the pump filter would't catch the junk?

Either the brakes or one of the wet clutches is coming apart and throwing debris. Are the brakes spongy? Did it have or does it have dual
power problems? Does the PTO slip?
You can change the oil and filters and milk a bit more time from it but in reality this is the time to find the source and fix it... It
won't be cheap now and it will be less cheap later. The next stage in the game is plugging the inlet strainer for the control pump section.
When that plugs you will lose oil supply to the dual power, PTO and FWD clutches and proceed to destroy all three with compromised pressure
in the interm...
Why does this stuff get through the filer? I don't know.... but it does. Been there, done THAT. Bought the t-shirt. Didn't like it. It's a
pain in the dick. You can clean the priority pack today and it may work for a year... but it might go in 5 minutes again too.
By your description of the material I would say a dual power plate is coming apart.... but i'm not there looking at it.
Usually brakes throw filings that will leave material the consistency of anti-seize compound.... that you will find on the magnetic drain
plugs.


Rod

The brakes work good, the duel power works good now that I rebuilt it and the PTO does not slip.

The short and sweet back story on it is when I got it nothing worked. PTO gears chewed up and missing (replaced), 4x4 housing broken(replaced) and 4 duel power clutches totally wore out replaced with 3 clutches broke the duel power hub at the snap ring groove (replaced) duel power hub and clutches.

How would you suggest a cheap and easy way of getting all the crap out of the inside. I have changed oil and filters more than once all ready that ant cheap. I thought the filters would catch what didn't drain out but I guess I was wrong.

There's no easy way on this.... I hope you scooped out all of the crap deposited around the internal webs when you had things open. Outside
of that.... I think I was doing 2-3 filter changes per oil dump. As soon as I noticed the pumps starting to whine a bit, change the filters
again. If the oil looks real putrid, try and get it warmed up good and dump the oil again...
I probably did 6-7 oil changes and at least twice that in filter changes over a year or so... and that was after scooping out as much crap as
I could find and spray washing the internal housings down in diesel. Eventually it will get better if nothing else is shedding material...

Your Cummins dealer may take pity on you and give you a volume break on a couple cases of filters... I usually get them for about 8 bucks
each if I take a case or two at a time...

Rod

Well I cleaned the priority valve, changed the oil and filters. The remotes work the lift does not. I figure some junk got down in the lift cover. The book shows valves in their. So that is were I'm headed next.

Any advice on how to remove the lift cover and get at the valves in their would be greatly appreciated. Thanks.

As best I can recall the only valve in the lift cover itself is the control valve spool. That's what you manually control with the lift
lever. I'm not saying it can't stick or get gummed up but that would be quite unusual...
Most likely one of the other spools in the priority pack is stuck or you just have no pump flow.... I can't remember if the unload valve is
the center one or on the right side... but it's one or the other and the other valve is a feathering valve. If that unloader is stuck then
all flow from the main pump will be dumped back to sump. I think the remotes should also be operating at half speed if that is the case...

If you want to go digging in the lift cover you have to remove the priority pack, the access hole in the floor, the remotes and all their
linkages, etc. Then you can either use a couple 2x4's to prop the cover up and slide it out or fix a bar of some type to the bolt holes on
top of the rock shaft and lift it out. This is a VERY TIGHT operation on a 7710 because of the load monitor linkage and parts. When you
start lifting the cover, raise it about 1" and then slip your hand in at the right rear and remove the pin and the LM linkage otherwise
you'll break something on that.... then carefully continue raising it out.
Personally I'd be more inclined to remove the priority pack and crank the engine over to see if the pump is actually lifting oil to the
cover first...
Have you checked to see if all the spools in the pack are moving freely?

Rod

Well I got 2000 psi at about 800 rpm at the remote plug bumping the handle.

When the lift stuck up the bottom pump was running constant like it was trying to lift past top. I shut it down and let it set for about 20 minutes it was hot. I started it back up and again it tried to raise past top and the pump whined I pecked on the priority valve with a hammer while it was running and something clicked and down it came has not raised sense.

My dad says a valve stuck and made it keep raising and now is stuck down. Now that you say it's it the valves to I guess I'll take it back apart. You have me thinking now it's probably in that valve that comes apart that I put the seat in.
Thanks!

OK I took the priority valve off and cranked the engine to see if there was oil coming up from the pump. Their is oil from both pumps coming out. I got to messing around with it and compressed air I can made the lift jump about an inch or two with air by blowing down the hole that matches with the the valve on the bottom. Cleaned the valves again it made the lift jump about the same as the air.

I think you are right it's all in the priority valves. Is it possible the valve pack could just be bad? Do you know of a good source for an aftermarket priority valve pack?

Thanks again for your help.

I have no idea if an aftermarket priority pack is even available....
One thing to check is the main system relief valve. If you have a spare of that swap it out or see if you can find one in an old pump
somewhere. You can also check the main pump flow and pressure by installing a special line fixture and flow control in place of the line
coming from the top of the pump.
Beyond that the only thing I can suggest is getting the OEM service manual and studying the hydraulic flow diagrams because at this point I
don't remember exactly how the plumbing is done in the priority pack or how to work around it for testing...
What I will say is that if the spools in the pack seem to move freely after you clean and lubricate them... then I would say the problem is
elsewhere.

Rod

Well I got it to working again. The valves was sticky in their holes. I cleaned the valve pack real good took 1000 grit sand paper and buffed the valves and their holes. Moved a lot better when I got done. Put it all back together and still nothing. My brother got to lifting the rear lift and I started moving everything that has to do with the lift in the cab and when I moved the draft lever all the way back and raised the lift lever it moved on it's own. Put the raise lever back down and moved the draft back into position control and she goes up and down.

I have no idea what was wrong or what fixed it. The bad part is I don't know what to do if it happens again.

I called the local New Holland dealer and they said they could get an aftermarket priority valve for $800. If I knew it would fix it for good it would be worth the $800.
Thanks again

If frigging with the lift lever and system selector got it working.... then you may have a worn pivot pin in the selector linkage along with
a control valve sticking a little bit due to the grime. The worn pin basically prevents the selector spring from applying full pressure to
the control valve... It may continue to work for quite a while. Who knows. If it quits again I'd probably just pull the lift cover and deal
with it that way.

Rod

I know it's been a while but I have ran it all summer and the lift will stop working and will not raise but a couple of inches. I can put the draft lever in low draft selection and the lift arms will raise up as I pull forward. Sometimes more than once and the lift starts working again.

I took the lift cover off today. I really can't see anything wrong with the linkages. It has been off before. It does have some writing on the lift cylinder in marker something about a bushing.

The book shows valves in the lift cylinder could any of these cause it to do this?