Deere 6400 Lost all Hydraulics Except PTO

[russhog]

Installed a used transmission housing on front of tranmission (pto would not work before intall). Pto works now but after the tractor got warm i was moving forward, hit the clutch. Now no hydraulics on power steering, wont move forward or back. no three point hitch power, pto will operate?

Any ideas?

 

[kennyd]

Welcome to TBN

You did refill the fluid correct

Run the tractor and see if the fluid is getting foamed up...possibly you have a air leak? The PTO is gear driven right?-so it would have no effect on the hydraulics.

 

[russhog]

i did fill properly, i did notice the fluid is foaming when i check the filler stick.
where would an air leak occur?

 

[kennyd]

Where? Did you take any filters off? Did you have to remove any lines under the tractor?

Foaming fluid indicates a leak on the return/suction side of the pump, so you may not see any external leakage.

 

[russhog]

Yes i took the front transmission pump housing off and replaced. There could very well be an air leak. Is there a screen that could be clogged as well? How do i go about stopping a leak?

 

[kennyd]

Yes i took the front transmission pump housing off and replaced. There could very well be an air leak. How do i go about stopping a leak?

Was there a gasket? Or is a sealant (RTV) used? If it's RTV-is is rated for hydraulic oil? Was it allowing to cure before refilling?

You took it apart, so you know everywhere it could be leaking from...I have never taken one apart. I am just offering general advice.

Is there a screen that could be clogged as well?

Not sure if there is a screen or not, I guess you don't have a manual?

 

[russhog]

I used the gasket maker to re-seal the housing when installed. I didn't use the maker on the intake tube. I have a technical manual on the 7410, some things are similar on this, but diagnostics are differnt. I guess i need to know
determine the items on the suction side.

 

[russhog]

Update. I drained the hydraulic oil and put two new filters on today. Refilled the fluid. I now can drive the tractor but i still have no power steering or three point hitch movement. Any Ideas?

 

[kennyd]

Is the fluid still foamy?

 

[J_J]

Have you put a gage in the pressure side of the pump, and and tried to steer. If you have PS, there is a priority valve that should get the fluid first? If you are not steering, the fluid goes on to the next valve.

 

[russhog]

i ordered the guage that was suggested, so i don't know the pressure yet.
I have checked all the valves on the bottom of the housing. the only one that wouldn't come out freely is the pressure regulating valve. it hangs just before it would come out.

 

[russhog]

The tech manual shows that the steering and hitch get fluid from the piority valve. Is this the valve on the back of the tractor. How does valve work?

 

[russhog]

Update: I have no pressure on the priority valve DR. The hose that goes down into the pto housing below the pirority valve on the rear of the tractor came loose and shot fluide out. This tells me the pump is pumping but I don't know how much? Any ideas from this info?

 

[russhog]

Finally got my guages. I don't have any pressure at the hyraulic test port on the main pump. I don't have a test port on the filter. Is there a way to check pressure from the charge pump? What would cause the main pump not to have any pressure?

 

[J_J]

Finally got my guages. I don't have any pressure at the hyraulic test port on the main pump. I don't have a test port on the filter. Is there a way to check pressure from the charge pump? What would cause the main pump not to have any pressure?

On the filter test point, you shoud not get more than 20 or 30 psi, as it is usually in the suction line or the return line. Some filters have a built in gage.

Yes, you should be able to measure the pressure on the charge pump, it usually is low, around 300- 400 psi. What so you consider the main pump? If you are talking gear pump, you can put a pressure gage in the pump out circuit, before any other valve.

Keep in mind, hyd fluid doesn't have much pressure unless it is pushing on something. If a valve is in the neutral position, the fluid is recirculating from pump to tank. To check cylinder relief pressure, hold the valve lever in the forward position until the cylinder extends and goes into relief.

 

[kenstrac]

I take it your JD is a closed system with a front mount pump and a charge pump in the belly check priority valve do you have a solenoid on the front pump?
BTW do you have brakes?

 

[J_J]

russhog

Do you have one of these transmission? You mentioned charge pump, so that tells me you have a hydrostatic transmission.

A priority valve is just that, it will give priority to the circuit that is critical for safe operation, such as steering over any other function. It probably has a relief valve. To check the pressure on the priority valve, put a gage at the input of the priority valve, and turn the steering wheel, or activate the other function that is in the circuit.

JD6400

Transmission:
Transmission: SyncroPlus

Forward: 12

Reverse: 4

Oil capacity: -unknown-
Comments: Standard transmission


Transmission:
Transmission: PowrQuad

Forward: 16

Reverse: 12

Oil capacity: -unknown

 

[kenstrac]

The fluid is picked up in the belly with a long metal tube with O rings as a seal but you said that you had pressure at priority valve the priority valve is probably dumping back to sump might be dirt in piston bore or broken spring Do not run the tractor for any amount of time or you will cook the front pump.

 

[J_J]

He said he had no pressure at the priority valve. Post #13

 

[kenstrac]

Update: I have no pressure on the priority valve DR. The hose that goes down into the pto housing below the pirority valve on the rear of the tractor came loose and shot fluide out. This tells me the pump is pumping but I don't know how much? Any ideas from this info?

He has fluid it's not going to the front pump its being diverted to sump.