Farmall 706 auxiliary valve leak solution possibilities

jimmyO

Member
Good evening.
Back to the Farmall 706...
I have a set of aux valves under the seat that leak lots of hytran. I need to stop the leaks.
My repair guy suggested that the old valves are not repairable, that there are no seals and no way to fix the leaks, so get new ones.
Ouch, I just know that's more money than I have in the piggy bank.
I have a 404 (504?) that the same repair guy took care of for me. Can't stop the leakage, so he ran some tubing so the leak would go back to the tractor instead of on the ground! OK, weird perhaps, but it works. You can see that setup in one of the photos.
I'd do the same thing on the 706, but as you can see in the other photo, the plumbing is to close to the valve vent. And it's all hard tubing, welded to the block, so I can't get fittings in there.

OK, here are the questions:
1. Is is true that the valves can't be rebuilt or new rings put in there or something?
2. Any ideas about how to get more room to add the fittings to bleed the leak back to the sump?

Thanks,
Jim
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The valves on the 706 are repairable for external leaks. I have repaired hundreds. He must have misunderstood some information about the internal leakage. All spool valves will leak internally and the more they wear the more they leak. That is what lets a hydraulic cylinder leak down under load and has nothing to do with the leaks to the outside. You do not have to take the valves off the tractor to repair. You pull the spool out the back but need to know what you are doing. That one valve with lines in the way will require some additional parts removal to pull spool.
 
Just my opinion, but that is not a repair. The leak is caused by a puny little o-ring on a tiny plunger(sold as one item). This should be repaired by someone that has proper equipment (and knowledge)for testing hydraulics as when the repair is done, the valve needs to be adjusted so the detent will hold while a cylinder is lifting an implement and then "kick off" when cylinder is fully extended.

Brian
 
Thanks both for the replies!
Brian, do the adjustments need to be done on a bench, or do they need to be done on the tractor when the thing is re-assembled? If I interpret your information correctly, it sounds like I replace the o-rings, then re-install the implement (in this case one set goes to a snow blower to control the chute, the other goes to a front loader) and then perform the adjustment ON THE TRACTOR with the tractor running while I operate the levers. Am I anywhere close?

As of yet, I don't know of any real tractor people nearby, so I'm kind of on my own.

Thanks again all.
Jim
 
They are repairable and like Pete 23 i have done coutless ones , What you need is 2 unlactching valves four O/Rings a good solid vice one med. straight flat blade screw driver and a drift punch that will fit in one of the three holes that the latching balls set in to take the valve apart so you can replace the latching valve . and a I T manual . To set the latching valve when done ya need a GOOD hyd. gauge about 2-3 foot of 3/8th high pressure hyd line one pioneer coupler and a gauge that can read 5000 PSI . You adjust the screw to hold the valve latched in till you reach max pressure for your system as that is where the valve should return to the neutral possession and on you 706 that should be around say 1500 -1750 . Now if someone before you installed a higher pressure relief it could go higher and you could adjust for that. Oh yea ya need to get 2 new plugs to help keep the dirt out of the back.
 
Hi Jimmy, the adjustment will need to be done after the valve is re-assembled on the tractor like pete and vet says. I think the system relief might be higher than 1750 but the valve pressure does not have to be any higher than 1750(system relief is usually higher than valve setting). The worst part in repairing these valves is getting the 3 detent balls back in where they belong. It probably will be easier doing them on a work bench verses having to do them in the field(which is how I had to do them when I worked at a dealership).

Good luck to you,
Brian
 
Brian , I have repaired some of my valves over the years and it is getting time to do some of them again. What is your opinion of just replacing the "puny little o-ring" on the tiny plunger, instead of both the o-ring and plunger? Years ago I showed the guys at the local hydraulics shop the tiny plunger with o-ring and they had the o-ring in stock, and they had a smaller size or two also. Talk about tiny o-rings!
 

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