1996 john deere model 5400 hydraulics problems

[johnlankford]

During the last 6-8 months I have noticed that my, 1996 John Deere model 5400 2wd tractor with only 980 hours, rear rockshaft arms seen to lift my 5ft bushog slower and slower. This tractor has a 6ft john deere front end loader also
that seems to operate normally. Two weeks ago, my bushog just all of a sudden dropped to the ground while I was cutting. When I pulled up on the lever to raise the cutter up, it would not come up at first. Then after about 1-2 minutes , it slowly started to lift. It would not reach normal lift height, even though the lever was at the highest lift position. To correct the hydraulics problem, I drained all of the oil, changed the hydraulic filter and cleaned the round 19" long stainless steel filter screen located at the rear bottom of the tractor next to the PTO shaft. This filter screen was covered in what appeared to be tiny silver metal flakes, no slime. After reassembly with new hydraulic oil, the rear rockshaft arms seemed to lift the bushog normally for about 15-20 minutes of work. Then, the same slow response lifting the cutter. Before condemning the expensive hydraulic pump, is there a bypass valve on the rockshaft control valve that can become clogged up to cause the problem I'm experiencing. And if so, how can I verify and correct this. What do you think is the correction? Please help me.

 

[cowski]

what kind of filter did you use?

 

[johnlankford]

what kind of filter did you use?

Genuine John Deere filter.

 

[J_J]

I advocate installing a hyd gage on every tractor.

It will let you monitor and trouble shoot the hyd system.

Here is why, the attachment is a gear pump that is pumping when the engine is running.

So if the pump is good and the componants that use the fluid are good, then something should work.

If not, where is the fluid going?

I would install a hyd gage in a tee in the IN port of the first valve, so that when all valve levers are in neutral, there should be no pressure in an open center hyd system.

Closed center hyd system may have pressure at all the valves when the engine is running.

So dealing with the 3pt, when you move the levers, is there any pressure showing on the gage?

Do you have pressure when moving any valve lever?

If you see relief pressure at any time, that will verify that the pump is good.

Trouble shooting can start at the problem, or at the start of pumping operation, which is the pump.

One of the best trouble shooting tips is knowing how something is supposed to work, and using the item correctly.

So install the hyd gage and go from there.

This test set should cost about $30.

JD 5400

Hydraulics:
Type: open center
Pressure: 2750 psi [189.6 bar]
Valves: 1 to 3
Pump flow: 11.4 gpm [43.1 lpm]
Total flow: 18.2 gpm [68.9 lpm]
Steering flow: 6.8 gpm [25.7 lpm]

 

[Tx Jim]

It's possible pressure relief valve(parts key #1) could have something keeping it from seating 100%. it's also possible rockshaft piston seal is leaking.

 

[jenkinsph]

The pressure guage to check the system is good advice and is handy to have for any number of issues now and later on.

The pressure relief valve should be easy to remove and check that Jim points out and would be the first thing to check if pressure was low.

The rockshaft piston seals will require more digging to get to but are highly suspect on my list. If the rockshaft valve was in the nuetral position when using the cutter and hitch and it suddenly dropped that would lead me to think either the piston seals are bad or the valve spool orings are bad. Right now I am leaning towards the rockshaft piston seals being the culprit.

 

[cowski]

do you have the draft control lever in the off position? with the tractor not moving but hot and running ,lift the bush hog up.see if it drops a few inches and picks back up.then see if it is a difference between idle and wide open.leave the bush hog up when you cut the motor off and see how long it takes to leak down.this will help determine if the rockshaft seals are bad.