Need help with a 7710 Ford

fordman81

Member
I have just bought a 7710 ford 4x4 with dual power and two remote valves. Nothing hydraulic works except the 3pt hitch. It works up and down fine with out a load on it ant tried it with a load yet. The pump on the right side of the transmission looks new. The pump on the left side of the motor looks factory. The local dealer said the pump on the trans works the remotes, dp and 4x4 and the pump on the left works the lift only. Is this true everything I find on the internet says opposite. Can anybody tell me without a doubt what pump works what? And when I say nothing works the pto don't turn at all you can grab it and turn in by hand with it engaged or disengaged. The lights switch from turtle to rabbit but is faster in turtle than rabbit. I assume one pump is totally shot. Any help will be greatly appreciated!
 
The main hydraulic pump is the one on the lower RH side of the axle housing. It is actually two pumps in one unit. The smaller pump powers the PTO, Dual Power, and 4WD circuits, and then the cooling/lube circuit as well. The larger pump serves the 3 point and remotes.

The pump on the LH rear of the engine is for the remotes only.
 
What Bern says is correct. The main pump in the rear axle housing is a tandem section pump. The front section of that pump supplies oil by priority to the hitch and secondly to the remotes. The rear section of that pump supplies control circuit oil for the dual power, PTO and FWD clutch. The engine mounted pump provides supplemental flow to the remote valves ONLY through a combining/sequencing valve in the priority valve pack on top of the hydraulic lift cover.

It would seem to me that if you have no remotes then there is a problem in the combining valve. There is a relief valve inside that spool that if it gets gummed up with dirt and brake filings... will hang the spool and not sense remote valve demand. So that's one problem.

The second problem... the PTO doesn't work and the dual power seems to not function correctly.... indicates to me that you have a MAJOR leak somewhere in that control circuit OR the inlet strainer is plugged and the pump section is cavitating and failing to supply flow/pressure.
Probably my first step given this situation would be to pull the mag plug (drain) on the bottom of the FWD transfer case and see how much crap is on the magnet. If it's got a lot then I'd pull the main filter and cut it open and look for crud. Also remove the rear section strainer (square white plastic plug to the rear of the filter) and see what crud is in that... I have a bad feeling that this old girl will take your wallet for a ride if you intend to fix it... My bet is that the brakes are actually shot and the filings from that are fouling up the hydraulic systems...

Rod
 

Or filters are stopped up due to slime and algae contamination.

Just went through that with a 5610 a year ago or so.

Put on new filters and it would work well for a couple of hours till the filters clogged up again. Owner is treating with an algicide and changing filters often after a complete flush.
 
When we got our 7600, someone replaced the hydraulic pump and did not get everything aligned with the pickup tube and pump was not connected to the tube at all. The only way that the pump would move any fluid was to overfill the rear-end enough so the pump was sucking unfiltered oil and not using the pickup tube. Can you drain the oil then pull the cover on the PTO valve side of the transmission to make sure the pump is aligned with the pickup tube?
 
Agree... only way for the suction to really not seal is if the o-ring was bad or the pump hung up on one of the dowels and that would be patently noticeable as soon as one added oil... cause it'd be pouring out around the pump.

Not to mention that the OP said the hitch is working fine so the main would have to be lifting oil for that to happen.

Rod
 

OK I have removed the pumps. The line that comes out the back of the lower pump that runs across the trans has a broken clip and missing the o-ring were it hooks on the pto valve. The oil looks clean very little metal from clutches. But their is some big pieces of metal in the 4x4 housing from the 4x4 housing being busted were the double gears set on the 4x4 clutches. Cut open one filter no great metal in there ether. I believe someone has changed oil an filter. Took air and blew in the lines for the lift, pto and remotes. The lift goes up as expected. The pto in the off position locks up and in the run position turn harder with air on it than without. And the remotes nothing still.

I am ordering a new pump and line with o-ring and seal. I am putting the 4x4 housing back on less the gears so it don't break anything else until I can get the other stuff to at least work some. As for the remotes I am going to remove and clean the valve body on top of the trans and see what happens then.

Is their anyway to bench test these pumps? I can hold my finger over the holes for the lift line on the big pump and it builds pressure and squirts across the room. Do the same on the pto hole and duel power and nothing. As for the smaller pump you can turn it and hold your finger over the pressure hole and as soon as you quit turning it it goes away.

Thank for all the help and I'll keep you up on any new findings.
 
Personally I wouldn't drop 1200 bucks on a pump until I could run it and test it... Put the new o-ring and clip on the line and fire it up. You will probably find that it was the main problem... You should see a 1/8" pipe plug in the lower part of the pump body. Install a 300 psi gauge in that port and run at fast idle. Should make 160-180 psi with warm oil. Run it through all the PTO, Dual Power and FWD clutch functions and watch for pressure loss and recovery time. If it doesn't recover, there is a leak in that clutch....

The main system pump is most often tested with a gauge in a remote. That should make 2500 psi @ 18 gpm flow... but if it makes 2500 while dead headed at idle it's probably close to spec...

Rod
 

I had a lot of problem with the oring and clip.. had to wrap up the oring with teflon to get the clip to stay on and hold. as next size oring was too big, and that size oring would pop loose...

but I dont know if the oring that was there was correct to start with. But its been about 4 years now and its still holding. And it fixed the pto dual power problem.
 
Yes, I agree... the OEM supplied O-ring of today is the incorrect size to make a seal. I forget if the diameter was wrong or the profile size was wrong... but I ended up making the correct ring by cutting/gluing the correct size buna cord for the job. I think it needs a bit fatter profile but that profile is generally not available in that small of a diameter in most kits.

Rod
 
Just a thought!
If you have all else working, except the remotes, check the load sensing line, from the priority pack back to the remotes, for blockage! I had that problem with my '82 5610! I found a piece of the tubing flange in the line that would intermittently block the flow, thus preventing the remotes from working!
HTH, Dave
 
(quoted from post at 22:18:03 10/22/15) Personally I wouldn't drop 1200 bucks on a pump until I could run it and test it... Put the new o-ring and clip on the line and fire it up. You will probably find that it was the main problem... You should see a 1/8" pipe plug in the lower part of the pump body. Install a 300 psi gauge in that port and run at fast idle. Should make 160-180 psi with warm oil. Run it through all the PTO, Dual Power and FWD clutch functions and watch for pressure loss and recovery time. If it doesn't recover, there is a leak in that clutch....

The main system pump is most often tested with a gauge in a remote. That should make 2500 psi @ 18 gpm flow... but if it makes 2500 while dead headed at idle it's probably close to spec...

Rod

OK I finally got gauges in and tested the pump. I am getting 170 psi at the pump on the right side of the tractor. The pressure only drops about 10 pounds when working pto and the pto still don't turn or brake when off. I can't tell if the duel power still slips in rabbit because I have the right rear wheel off but I only get a 10 pound drop when I work the button. I have found why the remote valve didn't work. It is suppose to have a ball bearing, spring and stop in the valve body and line going to the remotes. Only thing it had was the ball bearing. I removed the ball bearing and the remotes work with 2700 psi at fast idle dead headed. Got the spring and stop ordered.

Could the spring and stop have anything to do with the pto not working? How do I get to the pto clutch threw the lift arm cover or split the tractor? What would you do next?

Thanks for the advise on the purchase of a pump you saved me some dough on that one! But I was hoping for a simple fix.
 
The remotes and the PTO are completely unrelated. Replace the spring and clip that goes with that ball and that should fix the combining/sequencing valve that senses load in the remote circuit. Also bear in mind that this valve has an internal relief for the remotes WHICH ALSO ACTS as the ONLY relief for the engine mounted pump. Defeat that and you could shear the woodruff key in the cam gear or break the cam...

As far as the PTO problem... that will take some more ciphering. If it's not losing pressure when it's engaged, then that suggests to me that the piston and sealing rings are not leaking. If the brake isn't working and isn't causing a leak when the PTO is off... then I'd wager that there is a problem in the PTO control valve....... UNLESS you have a broken brake band or a broken output shaft from the PTO? Have you bothered to check to see if the internal shaft turns as viewed from the hydraulic pump hole while you turn the stub output shaft on the back? I mean... you could have a broken shaft internally or broken reduction gears and there is no problem with the PTO clutch.
If you haven't checked those shafts yet I'd probably take the top link rocker off and pull the plate in front of it to get a look at those shafts. Just don't withdraw the shaft or you may not get it back into the clutch pack... but you could turn the output shaft and make sure visually that everything inside is turning.
If that seems OK... and you are sure of the pressures... then I would go ahead and do a rear split to inspect the PTO clutch and possibly replace the PTO control valve.

Rod
 
(quoted from post at 11:57:08 11/06/15) The remotes and the PTO are completely unrelated. Replace the spring and clip that goes with that ball and that should fix the combining/sequencing valve that senses load in the remote circuit. Also bear in mind that this valve has an internal relief for the remotes WHICH ALSO ACTS as the ONLY relief for the engine mounted pump. Defeat that and you could shear the woodruff key in the cam gear or break the cam...

As far as the PTO problem... that will take some more ciphering. If it's not losing pressure when it's engaged, then that suggests to me that the piston and sealing rings are not leaking. If the brake isn't working and isn't causing a leak when the PTO is off... then I'd wager that there is a problem in the PTO control valve....... UNLESS you have a broken brake band or a broken output shaft from the PTO? Have you bothered to check to see if the internal shaft turns as viewed from the hydraulic pump hole while you turn the stub output shaft on the back? I mean... you could have a broken shaft internally or broken reduction gears and there is no problem with the PTO clutch.
If you haven't checked those shafts yet I'd probably take the top link rocker off and pull the plate in front of it to get a look at those shafts. Just don't withdraw the shaft or you may not get it back into the clutch pack... but you could turn the output shaft and make sure visually that everything inside is turning.
If that seems OK... and you are sure of the pressures... then I would go ahead and do a rear split to inspect the PTO clutch and possibly replace the PTO control valve.

Rod

Well Rod I did what you said and removed the back plate and boy did I find something. The double gear set on the top shaft is shot. The bigger gear is smooth no teeth and the smaller one is missing about half of it's teeth. The lower shaft is missing the gear or gears that runs against it. Fired it up and the top shaft turns when pto is turned on and stops when pto is turned off.

Now is it possible to change that top shaft out that hole the splines don't look that good? How many gears does that bottom shaft have it lists one for 540 and one for 1000 but it don't show very good if both goes in their at the same time?

Again thanks for all the advise.
 
Now you're getting somewhere....
The short answer to your question is.... MABEY. The shaft most certainly will pull out through that hole. That's not the problem. The problem is that when you go to install the new shaft the clutch plates in the clutch drum may drop slightly out of line... and that is all it takes to bugger your day. I guess what I would probably try given your situation... would be to apply line air pressure to the low pressure circuit again through the pump manifold and put the PTO lever in gear so it will lock the PTO clutch and hopefully compress the plates in place and HOPEFULLY you can still pull the shaft out with the plates compressed. Again, do this with air, not with the engine running, obviously.
What you want to watch is that the snap ring on the new shaft fully seats against the rear plate without having to force it in place or you're going to bugger the plates.
IF you can pull off that feat... then changing the bottom gears isnt' too bad of a job. You need to remove the drawbar housing, then remove the bottom arpeture plate... then you remove the PTO output shaft... then the 4 bolts in the retainer and haul the retainer back... then the gears will drop. I would suspect you're in for a complete house cleaning down there too. Watch for caged needle bearings (IIRC) and a couple thrust washers. It may require some help to get the gears back in place. They are rather heavy....

Now... if you get boogered up on the top shaft and it won't seat back in the clutch properly... I think given the magnitude of the problem and in wondering what else is royally fu**ed in there... I'd probably split her at the transmission/axle union. That is the ONLY WAY you can remove the clutch drum on a load monitor equipped tractor which the 7710 ought to be. You can with a great deal of misery change the plates, sealing rings, control valve, brake band and support through the lift cover but there is absolutely NO WAY to remove the drum without a split... and given the problems so far I'd not want to chance going in through the top to save half an hour only to find out it has to be split anyway.

You also want to get looking at salvage for those gears you need because CNH will bring on a heart attack if you try that route first. Fawcett tractor... or Alexanders... among others ought to have what you need, reasonably.


Rod
 
(quoted from post at 21:50:50 11/06/15) Now you're getting somewhere....
The short answer to your question is.... MABEY. The shaft most certainly will pull out through that hole. That's not the problem. The problem is that when you go to install the new shaft the clutch plates in the clutch drum may drop slightly out of line... and that is all it takes to bugger your day. I guess what I would probably try given your situation... would be to apply line air pressure to the low pressure circuit again through the pump manifold and put the PTO lever in gear so it will lock the PTO clutch and hopefully compress the plates in place and HOPEFULLY you can still pull the shaft out with the plates compressed. Again, do this with air, not with the engine running, obviously.
What you want to watch is that the snap ring on the new shaft fully seats against the rear plate without having to force it in place or you're going to bugger the plates.
IF you can pull off that feat... then changing the bottom gears isnt' too bad of a job. You need to remove the drawbar housing, then remove the bottom arpeture plate... then you remove the PTO output shaft... then the 4 bolts in the retainer and haul the retainer back... then the gears will drop. I would suspect you're in for a complete house cleaning down there too. Watch for caged needle bearings (IIRC) and a couple thrust washers. It may require some help to get the gears back in place. They are rather heavy....

Now... if you get boogered up on the top shaft and it won't seat back in the clutch properly... I think given the magnitude of the problem and in wondering what else is royally fu**ed in there... I'd probably split her at the transmission/axle union. That is the ONLY WAY you can remove the clutch drum on a load monitor equipped tractor which the 7710 ought to be. You can with a great deal of misery change the plates, sealing rings, control valve, brake band and support through the lift cover but there is absolutely NO WAY to remove the drum without a split... and given the problems so far I'd not want to chance going in through the top to save half an hour only to find out it has to be split anyway.

You also want to get looking at salvage for those gears you need because CNH will bring on a heart attack if you try that route first. Fawcett tractor... or Alexanders... among others ought to have what you need, reasonably.


Rod

Well the shaft isn't bad. I did pull it out the back hole. It was a PITA to put back but thought it was best to have a look. The previous owner that gutted it put the top double gears on backwards and it only splines on the one end that's what had me thinking the shaft might be bad. Got all new gears, thrust washers and bearings ready to go in now. Is their a trick getting those bottom big gears in they look like a real tight fit? I never took the old ones out. Do they go in one at a time or both together?
 

I am having the same remote issue with my 7710. Just wondering if you got yours fixed and if so how???

Or for anyone to give advice.
 
(quoted from post at 19:04:47 03/24/18)
I am having the same remote issue with my 7710. Just wondering if you got yours fixed and if so how???

Or for anyone to give advice.

Yes I did. My problem was in the priority valve under your feet on top the trans. It was FULL of metal from all the bad P.T.O. gears. For some reason the filters didn't catch all the metal. I have had the lift stick up, the remotes quit and the lift fall under load and not want to lift back up. Take that valve off and clean it and I would get some small metal out of it took about three or four times cleaning the first year we ran the tractor.
 

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