[clayjd]

I recently bought a 1976 2640 to use for hay. Now everything on it seems to work like it should but the rear SCV's wont fold my mower back up it will pick it up about 4 inches but that is it all other hydraulics seem to be working as they should. if anyone can give me some trouble shooting advice so i can narrow down what could be the problem it would be much appreciated.

 

[Tx Jim]

Welcome to GTT
Is hyd at full mark on the dipstick? How long since hyd filter has been changed? I suggest you get a 5000 psi gauge then install a male hyd coupler tip. Plug gauge in breakaway coupler then operate lever to activate gauge to check pressures & note the pressure amounts. Stand-by hyd pressure should be 2250-2350 psi.
With 3 pt raised, engine idling at operating temp look inside hyd filler hole behind seat for moving oil. Moving oil indicates faulty 3 pt control valve seals.

 

[clayjd]

Welcome to GTT
Is hyd at full mark on the dipstick? How long since hyd filter has been changed? I suggest you get a 5000 psi gauge then install a male hyd coupler tip. Plug gauge in breakaway coupler then operate lever to activate gauge to check pressures & note the pressure amounts. Stand-by hyd pressure should be 2250-2350 psi.
With 3 pt raised, engine idling at operating temp look inside hyd filler hole behind seat for moving oil. Moving oil indicates faulty 3 pt control valve seals.

Hydraulic oil is full, I can't see any oil moving or spraying inside the housing, and I hooked the tractor to my baler bc it has a pressure gage for seting the density of the bales and I increase the pressure requirement to max and the tractor will only put out 1900 psi also the pressure will slowly leak down, and I'm going to change the filter tomarrow after work

 

[Tx Jim]

1900 psi on baler gauge & gauge attached directly to scv could show different pressures. Hyd pressure leaking down on scv is a caused by a poppet control valve in scv not seating correctly. Does your tractor have option of hyd hi-lo or IPTO? Does it have a FEL? Does any hyd control valve fell hotter than another control valve? Its possible pressure control valve by hyd filter is blocking some pressure to SCV.

Has hyd suction screen been checked/cleaned lately?

 

[clayjd]

1900 psi on baler gauge & gauge attached directly to scv could show different pressures. Hyd pressure leaking down on scv is a caused by a poppet control valve in scv not seating correctly. Does your tractor have option of hyd hi-lo or IPTO? Does it have a FEL? Does any hyd control valve fell hotter than another control valve? Its possible pressure control valve by hyd filter is blocking some pressure to SCV.

Has hyd suction screen been checked/cleaned lately?

I'm going to pick up a gauge tomorrow and ill check the screen tomarrow when I change the filter, where is the pressure control valve neer the filter located so I can check it as well, also it dosen't have a fel and it has IPTO with manual shift hilo

 

[Tx Jim]

where is the pressure control valve neer the filter located so I can check it as well,

View link I posted of PCV. Another location to check for internal hyd leak is the power steering valve.

https://partscatalog.deere.com/jdrc/sidebyside/equipment/79943/referrer/navigation/pgId/250783

 

[Zebrafive]

I'd start with a pressure check as TxJim first suggested.

 

[clayjd]

Ok i changed fluid and filter and while there was a little break material in the strainer it was nowhere near plugged, after cleaning it and putting fresh fluid in i was able to get 1700 psi at the scv

 

[Tx Jim]

Could be as simple as pressure control valve located close to hyd filter is limiting pressure. I'll suggest to check hyd pressure on steering supply line or frt hyd pump.