Need some advice on a 1977 JD 310A. Machine is one owner with 7500 hours. Recently
hydraulics stopped working. Machine had sump screen cleaned and filters/hydraulic
oil changed about 30 hours before hydraulics stopped. Pretty sure charge pump in
transmission is good because machine still moves forward and reverse in all 8 gears
with no issue and with same power as always. Loader, hoe, and steering are dead.
Stabilizers will move but very, very slowly and with no power.
Had already planned to change main pump because machine was getting weak and had one
on hand with a new destroke solenoid so we put them on, no change. Before new pump
was changed system was flushed and all possible old fluid removed. Used a magnet to
"sweep" the sump then filtered old oil and checked pump for metal. Found a less than
enough to fill a 1/8 teaspoon measuring spoon and most of that was in the pump on a
magnetic plug. Expected much more to be in a 43 year old machine.
So far, in addition to changing main pump, we have removed, cleaned, and put new
seals & orings on the pressure control valve on the side of transmission and the
filter relief valve on hydraulic system (the one that the cartridge is horizontal).
Planning to check, clean and reassemble the larger more complicated filter releif on
the other filter next. Have also ordered a set of test gages but am almost positive
we have a bypass or relief stuck open on the intake side of the main hydraulic
system. System has flow but does not enough to build pressure.
Any advice would be appreciated.
hydraulics stopped working. Machine had sump screen cleaned and filters/hydraulic
oil changed about 30 hours before hydraulics stopped. Pretty sure charge pump in
transmission is good because machine still moves forward and reverse in all 8 gears
with no issue and with same power as always. Loader, hoe, and steering are dead.
Stabilizers will move but very, very slowly and with no power.
Had already planned to change main pump because machine was getting weak and had one
on hand with a new destroke solenoid so we put them on, no change. Before new pump
was changed system was flushed and all possible old fluid removed. Used a magnet to
"sweep" the sump then filtered old oil and checked pump for metal. Found a less than
enough to fill a 1/8 teaspoon measuring spoon and most of that was in the pump on a
magnetic plug. Expected much more to be in a 43 year old machine.
So far, in addition to changing main pump, we have removed, cleaned, and put new
seals & orings on the pressure control valve on the side of transmission and the
filter relief valve on hydraulic system (the one that the cartridge is horizontal).
Planning to check, clean and reassemble the larger more complicated filter releif on
the other filter next. Have also ordered a set of test gages but am almost positive
we have a bypass or relief stuck open on the intake side of the main hydraulic
system. System has flow but does not enough to build pressure.
Any advice would be appreciated.