m5700, changed hydraulic oil and filter, hydraulics not working

[Rex-man]

Decided to change out the Hydraulic fluid and replace both filters. Tractor was operating fine. Replaced filter with Kubota brand and used Kubota Super UTD oil. Started it up and no power steering. no 3 point or loader is working. Looking for suggestions.

 

[Dave_eng]

A couple of observations which will become clearer if you study the following marked up image.

Your tractor has a tandem hydraulic pump. i.e. one pump stacked unto another pump.

Both pumps share one suction line.

The end pump closest to the engine is the main pump driving all but: power steering and pto clutch.

You mention the power steering is not working but will the pto clutch engage.

Since the power steering does not work then I would be suspecting an air leak into the suction side of the two pumps. O rings 050 in the suction line and 080 connecting the suction line to the two pumps would be suspect.

Another thing to consider would be to disconnect the discharge line from the main pump, pour a small amount of hydraulic oil into the pump and then crank the engine. Do not start it or you will have a big mess should the pump start to work. It may be that you have an air lock in the pump which is preventing it from starting to pump.

Dave

 

[Rex-man]

A couple of observations which will become clearer if you study the following marked up image.

Your tractor has a tandem hydraulic pump. i.e. one pump stacked unto another pump.

Both pumps share one suction line.

The end pump closest to the engine is the main pump driving all but: power steering and pto clutch.

You mention the power steering is not working but will the pto clutch engage.

View attachment 57147

Since the power steering does not work then I would be suspecting an air leak into the suction side of the two pumps. O rings 050 in the suction line and 080 connecting the suction line to the two pumps would be suspect.

Another thing to consider would be to disconnect the discharge line from the main pump, pour a small amount of hydraulic oil into the pump and then crank the engine. Do not start it or you will have a big mess should the pump start to work. It may be that you have an air lock in the pump which is preventing it from starting to pump.

Dave

Thanks Dave, haven't checked the PTO yet, will in the morning. I can't imagine the O-rings would be bad since everything worked fine before the oil change and I did not disturb anything on the pump.
The air lock in the pump would make sense though. I believe the pump has two discharge lines on the top, Are you saying to remove both, add the oil, replace the lines and then start it? Rex

 

[Dave_eng]

Thanks Dave, haven't checked the PTO yet, will in the morning. I can't imagine the O-rings would be bad since everything worked fine before the oil change and I did not disturb anything on the pump.
The air lock in the pump would make sense though. I believe the pump has two discharge lines on the top, Are you saying to remove both, add the oil, replace the lines and then start it? Rex

With air leaks on the suction side of the pumps, air will leak in whereas oil will not leak out the same weakness.

I would just try priming the main pump and if it starts it may get the ps pump working by eliminating any air in the suction line.

If this works, please report back as it helps us all learn.

Dave

 

[whitetiger]

Decided to change out the Hydraulic fluid and replace both filters. Tractor was operating fine. Replaced filter with Kubota brand and used Kubota Super UTD oil. Started it up and no power steering. no 3 point or loader is working. Looking for suggestions.

Rev it up for a couple of seconds while you are trying to turn the steering wheel. It works every time for me.

 

[Motion]

Did you put in what you took out including filters? Is the fluid at the correct level?

 

[Rex-man]

With air leaks on the suction side of the pumps, air will leak in whereas oil will not leak out the same weakness.

I would just try priming the main pump and if it starts it may get the ps pump working by eliminating any air in the suction line.

If this works, please report back as it helps us all learn.

Dave

Dave, unhooked both upper lines and put hydraulic oil in and replaced and it didn't seem to do anything. Also, the clutch does work, tractor will move.

 

[Rex-man]

Did you put in what you took out including filters? Is the fluid at the correct level?

Yes, fluid level is correct, filters and oil from Kubota.

 

[Rex-man]

Rev it up for a couple of seconds while you are trying to turn the steering wheel. It works every time for me.

Just tried that and it didn't seem to help. I'm a little worried about running it too long with no oil going into the pump

 

[Motion]

Your first post was yesterday afternoon, if you kept trying you may have caused air to become entrained in the fluid. I'd suggest letting it sit for 24 hours. If this is the case your pump/pumps are cavitating. Just my .02

 

[Dave_eng]

Loosen both suction line connections to the two pumps.

Put shop vac into blowing not sucking and blow into transmission. Watch for oil to be forced out the joint between suction lines and pump.

If you can get oil to come out at this point, tighten connection and loosen discharge connection at pump. With shop vac running, crank engine but do not start and see if oil comes out. If it does then tighten connection and start engine.

I was talking about the pto clutch not the main drive clutch. The pto clutch is powered by the ps pump.

Daave

 

[Rex-man]

Loosen both suction line connections to the two pumps.

Put shop vac into blowing not sucking and blow into transmission. Watch for oil to be forced out the joint between suction lines and pump.

If you can get oil to come out at this point, tighten connection and loosen discharge connection at pump. With shop vac running, crank engine but do not start and see if oil comes out. If it does then tighten connection and start engine.

I was talking about the pto clutch not the main drive clutch. The pto clutch is powered by the ps pump.

Daave

Dave, that did the trick! Everything works fine now. Just an FYI for everyone. Its easier to pressurize the transmission using the fill access on top of the transmission. You have to access it through the cab but its much easier to get to for filling and for this procedure. You probably want to block off the vent pipe in the back though. thanks for the help!

 

[GeoHorn]

Yep... sounds like the pump simply lost its’ prime. It should have regained it on its’ own shortly, but the air pressure likely sped up the process.

 

[fried1765]

Same problem (no hydraulics after changing fluid and filters), a simple solution for me. Since my bucket cylinders were extended, I held the control as if to curl the bucket, then used a jacket to curl it, compressing the cylinders. This returned fluid to the pump and hydraulics worked on start up. Might be able to do the same thing by jacking up the 3-point hitch arms (?). I suspect it is also what happens with the steering maneuver above; not sure.

Used leather, or fabric "jacket"?

 

[whitetiger]

Your hydraulic oil does not return from the loader to the pump.
Kicking the left rear tire twice will have the same effect as jacking up the bucket.

 

[Als Fixit]

Your hydraulic oil does not return from the loader to the pump.
Kicking the left rear tire twice will have the same effect as jacking up the bucket.

Not exactly. Correct, the fluid returns to the reservoir, which in turn apparently forced some fluid into the suction line. It did work. Kicking the tire did not.

 

[whitetiger]

forced some fluid into the suction line

It just does not work that way.

 

[North Idaho Wolfman]

Same problem (no hydraulics after changing fluid and filters), a simple solution for me. Since my bucket cylinders were extended, I held the control as if to curl the bucket, then used a jack to curl it, compressing the cylinders. This returned fluid to the pump and hydraulics worked on start up. Might be able to do the same thing by jacking up the 3-point hitch arms (?). I suspect it is also what happens with the steering maneuver above; not sure.

Not exactly. Correct, the fluid returns to the reservoir, which in turn apparently forced some fluid into the suction line. It did work. Kicking the tire did not.

If your returning fluid to the reservoir was forcing fluid into the pump you would have had serious issues, like a plugged vent.

Walk back to your three point and pick up on the lift arms, HUMMM not pressure there.

This is a long shot, but what may have happened is that when you opened the valve and jacked up the loader you created a small vacuum on the pump, pulling in a little fluid and priming it.
Not the best way to do it, but I guess you got it to work for you.