D17 series 4 hydraulic valve leak

Howdy, I have been fighting an issue with part of the valve stack on my d17 series 4.   I added the 3rd valve to be able to add a tilt cylinder for the bucket here soon. I had things apart so I added it and capped the ports since I’m not ready to use it.

That valve is constantly pushing oil out of the back of the valve. I have redone all orings on the spool multiple times thinking I nicked it or the orings weren’t correct so I ordered agco rings , same thing happens.

In some research I saw it mentioned it was bad to cap them off and instead they need to be looped, in my mind it’s no different than having a cylinder installed and it not being used but ok…can’t hurt to try and this point so I looped the ports with a hose, same issue.   I haven’t redone orings since I looped it so I suppose slight chance they are an issue but in none of the rebuilds of that spool, have I found an oring that has torn or other visible issue.

On another forum someone mentioned a similar issue and he had a bent screw for the poppet, I haven’t investigated that yet but I wanted to see if there is a D17 s4 hydraulic guru lurking on here that might know what the heck is going on. I tested pressures and they are good. This valve is the same husco part number as the loader valve.

The other loader and rear ram valves work just fine. I’m at a loss here, not super great with hydraulics for one and also not finding many who mess with the D17 s4 design.   

I welcome any ideas you all have, sorry for the long post but I wanted to get the back story out there to maybe help someone pin things down.

Thanks!!! Todd

I have replaced it a few times and yes, it’s an awful little critter to deal with lol.   Unfortunately I have replaced every seal front to back a few times for the valve.

I’ll give that a check, I need to finish up some work on the 45 and then the 17 gets to come indoors for brakes and so I’ll try that idea and see If I can learn anything. Thanks!

Edited by Toddmac66 - 11 Jul 2026 at 11:56am

it's been many years since I added that same valve to the stack on my D17s4

Edited by Gatz in NE - 12 Jul 2026 at 1:09pm

Today I had time to yet again attempt to sort out the leaking valve, wired linkage so it was at float and ran it with the rear cap off the valve, 100% coming out of the center of valve. Tore it down and ran thru Orings and swapped on a different end with spring and screw and the inner components for detent. No difference, she leaks as always.
Being the last valve in the stack, it has the side capped off, is it possible the internal check valve and spring shouldn’t be installed or something dumb along those lines ?   
I’m running out of ideas other than once I bring it in the shop to do brakes, I’m gonna at least remove that valve and check it for cracks and ensure torque on the stack is good. I have one more used valve I may swap into place for lack of a better idea.   With it being the only one in the stack that leaks and it’s next to an identical model valve, I’m a bit frustrated with this critter.

Yes between each valve there is what I call a check valve…maybe wrong terminology for it. It is in there but I also wonder if maybe it shouldn’t be since it’s the last valve in the stack, I have no basis for such a thought other than just trying to think thru things ….clearly incorrectly so far.

DrAllis wrote: Oil is coming from the center of the spool ??  And you tried a different pressure release adjustment screw with a good Oring on it ??   There must be something wrong with that particular spool inside where the Oring has to seal.  The "load check" poppet in the side of the valve isn't the problem.

Yes, replaced the orings. I agree, I think I’m dealing with a crack or something I can’t see easily. I did however luck out and just bought an actual Husco 5000 series factory manual on eBay which sure doesn’t hurt my feelings any.   Kinda feel like I hit the lottery lol.
I definitely can’t rule out me accidentally mixing up the spools , I don’t think I did cause I know they are fitted individually but I’ve done dumber stuff so I may swap em just for the heck of it, after that I think it’s time to take it apart when I have it stripped down to pull finals to do brakes.    

DrAllis wrote: When I do brakes on any of those tractors with the right side hydraulics, I never remove those valves. I spend a little time disconnecting linkages underneath and wiring them up out of the way. A proper length 2 x 4 jammed between the platform and the underside helps raise things up an inch and the axle comes right out under it.

I don’t think I would either but it feels like now is the time to investigate the valve since I’ll be right there handy. Not too excited about it, the lines and clearance to axle housing and all that involved really sucks to get to. Originally it was just gonna get the fenders removed and swapped out and I was gonna support the valve assembly and leave it be but this leak has altered things. Maybe I’ll get lucky and a spool swap will do the trick and it won’t come to a removal of the whole thing. I really want to retorque the stack and replace that section o ring…again anyway.

That model of Husco valves from 1964 til 1981, (in my opinion) get a 9.5 rating on a 1 to 10 scale. They were quite trouble free, performed faaaar better than any 4010-20 John Deere, had a very nice control feel to them, and on and on. For those of you who have never operated a New Generation Deere with dash mounted hydraulic levers, the A-C system (started with the One-Ninety) was superior for sure.