Ford 960 Hydraulic question

[leester]

Hello,
I'm working on refurbishing a 1955 Ford 960. When I got it the 3pt did not raise and so I went through the process of tearing into the top lid. I had to unstick the control valve and unloading valve. I also replaced the lift piston and seals, the badly worn pivot pin, safety valve and put in new fluid. Pump and relief valve checked out ok. Put it together and it lifted the full range with no load and no leaks. Thought I was good.
I have a carryall box I built for my other tractor that I put on the back and gave my 2 sons a ride(7&9). Certainly less than the 1250lbs the lift is rated for. It lifted the carryall less than a foot off the ground and would hold it there, but there was a steady leak out of the check valve plug. I had pulled out the check valve spring and ball when I did the other work, cleaned it and put it back in. I did not pull the check valve seat out. Could this be the issue? Looks like I may need a new o ring for the check valve. Does anyone happen to know the proper bolt thread for removing the check valve seat?
Any ideas on where you would start re- checking given the symptoms mentioned earlier?

Thanks!!

 

[Btzj02]

I used a 3/8" by 24 threaded rod about 4" long. If you tear into it again I would recommend you check and adjust the gap on the control valve. My 4000 shop manual shows: Constant draft = .395"-.397" and Position control = .448"-.450" Check out the "Chicken House Mechanic" on Utube, he walks you through the procedure or, get the shop manual.

 

[leester]

I used a 3/8" by 24 threaded rod about 4" long. If you tear into it again I would recommend you check and adjust the gap on the control valve. My 4000 shop manual shows: Constant draft = .395"-.397" and Position control = .448"-.450" Check out the "Chicken House Mechanic" on Utube, he walks you through the procedure or, get the shop manual.

Thanks for that info, I'll give it a try

 

[shaun wallace]

There is a spring and plunger for back pressure behind it.

 

[leester]

Hi all, just circling back to give an update. Pulled the check valve seat and all was good, othen than replacing all the seals along the way which stopped the leak I had experienced. As btzj suggested I got the I&t manual from the library and watched the chicken house video. The position control adjustment was way out of spec. Al seems to be working as it should now. Thanks again

 

[John P.]

I used a 3/8" by 24 threaded rod about 4" long. If you tear into it again I would recommend you check and adjust the gap on the control valve. My 4000 shop manual shows: Constant draft = .395"-.397" and Position control = .448"-.450" Check out the "Chicken House Mechanic" on Utube, he walks you through the procedure or, get the shop manual.

Thanks for the tip, he has some good videos!