JD400 Hydraulic blowout

[amathonn]

I have a John Deere 400 Industrial that has been working fine until one day it decided to suddenly blow out much of the hydraulic fluid, apparently past the hydraulic filter o-ring/gasket at the top of filter housing. I cleaned the screen and put in a new filter. O ring looked fine so I replaced it (bought a new one but JD dealer gave me wrong size) Started it up and again sprayed out hydraulic fluid from side of hydraulic filter. Tried the three-point lift and it was not working. Acts like fluid is blocked. Suggestions?

 

[Tx Jim]

Check to be sure frt hyd pump shaft is turning when engine crankshaft is turning. It's possible stroke control valve in frt hyd pump has debris in valve seating area keeping frt pump from pumping oil.

 

[amathonn]

Check to be sure frt hyd pump shaft is turning when engine crankshaft is turning. It's possible stroke control valve in frt hyd pump has debris in valve seating area keeping frt pump from pumping oil.

Thanks, I'll check that!

 

[true temper]

There is a filter relief valve under the right hand floor board. I think it takes an 1 1/4“ wrench, see if its stuck.

 

[Zebrafive]

There is a filter relief valve under the right hand floor board. I think it takes an 1 1/4“ wrench, see if its stuck.

I was going to mention that. The filter relief should send excess oil back to sump (transmission case)

 

[Tx Jim]

It would surprise me if there was any excess oil from trans pump while supplying oil to frt pump. All it would take is a small high pressure internal leak to utilize any excess output from trans pump.

 

[Zebrafive]

I was thinking front pump not pumping. Failed coupling, destroked?

 

[amathonn]

There is a filter relief valve under the right hand floor board. I think it takes an 1 1/4“ wrench, see if its stuck.

I found the location of filter relief valve with the 1-1/4" plug/cap. Cap came out easy, but the valve itself won't budge and I didn't want to put much force on it for fear it would break. Any suggestions?

 

[true temper]

I cant remember what is going on in there for sure, its been too many years since I have worked on one of them. Maybe take some large internal snap ring pliers and pull on it. I think the valve is pretty tuff I don’t think you will hurt it.

 

[Zebrafive]

I found the location of filter relief valve with the 1-1/4" plug/cap. Cap came out easy, but the valve itself won't budge and I didn't want to put much force on it for fear it would break. Any suggestions?

Spray with solvent or penetrating oil. It is sleeve with a spring pin cross ways at each end with a spring and pin inside.
Since it will not come out it may be stuck open. The pin inside move towards the outside against the spring.
Can you hook the spring pin and pull it (assembly, not the spring pin) out?
Maybe grab the spring pin with needle nose pliers and twist and pull?