How to bleed hydraulics on front end loader?

[MadJack]

My FEL is most times slow to respond, comes up about a foot, stalls, then goes up smooth at 1500+ rpms.
Letting the FEL down it responds well with initial stop but then creeps down 3 to 4 inches fairly quickly.

I'm suspecting air in the system is causing this. Can anyone explain where/what line to bleed air from the system?
Tractor is an '86 Ford 2110 (Jap model).

(A friend suspects air, and possibly a bad spool valve)

 

[kennyd]

Hydraulic systems are self-purging, there is no need to "bleed" the system.

 

[Doughknob]

Yeah, not sure that is the case. Self purging assuming all air bubbles can migrate to the reservoir. One my be stuck in a hose loop in the loader. I’d point the tractor & loader down the steepest hill i could find and cycle all the controls a while.

 

[ROUSTABOUT]

Never heard of such.

 

[npalen]

I'm wondering if your valve has no load checks installed and/or if you are letting it free-fall when lowering. Either one would tend to induce air. Try raising and then lowering slowly several time letting the pump keep up with the cylinders to see if this doesn't purge the air.

 

[kennyd]

Yeah, not sure that is the case. Self purging assuming all air bubbles can migrate to the reservoir. One my be stuck in a hose loop in the loader. I’d point the tractor & loader down the steepest hill i could find and cycle all the controls a while.

Air can get pushed past the seals whereas fluid cannot. Do you think dealers or the factory bleeds loaders when they install them?

 

[4570Man]

Hydraulic systems are self bleeding if you cycle it a few times. But it sounds like the pump may be sucking air. Have you checked the hydraulic oil level?

 

[M59]

MadJack,

The usual route for hydraulic fluid, under high pressure, out to the cylinder and then back to hydraulic reservoir via a low ( no pressure) pressure line where entrained air or vapor ( air bubbles or vaporized water if excessively contaminated fluid is in use and fluid is very hot) is separated out. The reservoir is vented to the outside by one way valve.

It would be highly unusual, unless you had a constant inflow of air past a seal, for air to be constantly in the hydraulic system.

Since the Ford 2110 FEL cyclinders are double acting ( you power up and power down ), I believe your issue is more hydraulic control related ( control valve, shuttle/spool valve, unknown restriction, damaged piston, ?? ) related and not air in the system.

 

[MadJack]

MadJack,

The usual route for hydraulic fluid, under high pressure, out to the cylinder and then back to hydraulic reservoir via a low ( no pressure) pressure line where entrained air or vapor ( air bubbles or vaporized water if excessively contaminated fluid is in use and fluid is very hot) is separated out. The reservoir is vented to the outside by one way valve.

It would be highly unusual, unless you had a constant inflow of air past a seal, for air to be constantly in the hydraulic system.

Since the Ford 2110 FEL cyclinders are double acting ( you power up and power down ), I believe your issue is more hydraulic control related ( control valve, shuttle/spool valve, unknown restriction, damaged piston, ?? ) related and not air in the system.

Thank you M59!
I did recently change all hydraulic fluid and replace it, and a new filter. Some improvement which allows/encourages me to run it more, but still not as good as other tractors I've owned before.

Good excuse to upgrade to a single stick, possibly 3 spool with electric 3rd... (possible grapple or just a forks-finger in the future)

 

[4570Man]

Thank you M59!
I did recently change all hydraulic fluid and replace it, and a new filter. Some improvement which allows/encourages me to run it more, but still not as good as other tractors I've owned before.

Good excuse to upgrade to a single stick, possibly 3 spool with electric 3rd... (possible grapple or just a forks-finger in the future)

Can you see the hydraulic fluid in the tank to see if it’s aerated or foamy after using it?

 

[LD1]

Check the suction side for air leaks

 

[Jims1025R]

As said, free falling or floating may have let air suck in. Operate the loader and bucket slowly to the full limit of travel slowly. When the full travel is reached (particularly bucket dump) hold the valve until you hear the hydraulic system load up, and the cylinders strain a little. The time between reaching the travel limit, and the hydraulic system loading up, is the air being purged out, which is the objective - a little time required for that!

 

[cbg8670]

On my LS I have to keep rpm high . it will get jerky at low rpm

 

[rScotty]

Check the suction side for air leaks

What he said. Sounds like you have an air leak on the suction side somewhere between the reservoir and the intake to the hydraulic pump. That path includes the filter. Somewhere air is being pulled into the fluid going to the hydraulic pump.

If you are not seeing oil on the ground after running, or an oil slick coating on a pipe or hose, it is because the air leak is above normal oil level in the hydraulic reservoir.

It may be as simple as a pinhole in a rubber line or a connector not seating fully. If you have any rubber suction line with hose clamps, that's where it is.

rScotty

 

[rScotty]

On my LS I have to keep rpm high . it will get jerky at low rpm

That isn't normal for any hydraulic system. You might want to fix it.
rScotty

 

[MadJack]

Lots of info posted here.
Thanks guys

 

[Jofang]

Forget looking for air in the system. Hydraulic oil travels so fast through the components in the circuit that air has got no chance to settle anywhere. I suggest that the FEL falling 3 to 4 inches indicates the problem. Depending upon your circuit design the spool valve, the pilot operated check valve and the cylinder seals should hold the FEL in position almost indefinitely. I don't recall you mentioning the age of your tractor.

 

[priberc]

Sounds to me like you have an air leak in your supply/suction line from the tank to the pump.....inspect and look for anything "wet" This is not under pressure so it will not force fluid out at any time....oil will just "weep" from wherever it is sucking air into the system. Look for rub points/hoses rubbing together or your suction/supply line rubbing on something and look for collection of dust/dirt that is oily/wet

 

[ptsg]

Forget looking for air in the system. Hydraulic oil travels so fast through the components in the circuit that air has got no chance to settle anywhere. I suggest that the FEL falling 3 to 4 inches indicates the problem. Depending upon your circuit design the spool valve, the pilot operated check valve and the cylinder seals should hold the FEL in position almost indefinitely. I don't recall you mentioning the age of your tractor.

Unless there is a crack on the rubber hoses on the suction side of the pump. Then all bets are off.

 

[MadJack]

Forget looking for air in the system. Hydraulic oil travels so fast through the components in the circuit that air has got no chance to settle anywhere. I suggest that the FEL falling 3 to 4 inches indicates the problem. Depending upon your circuit design the spool valve, the pilot operated check valve and the cylinder seals should hold the FEL in position almost indefinitely. I don't recall you mentioning the age of your tractor.

"Tractor is an '86 Ford 2110 (Jap model)."

After running it some today, I'm fairly sure my issue is the spool valve.
After an hour of run time I went to park it. When lowering the bucket (FEL) the bucket dropped a couple inches then proceeded to climb slowly! (lever in the down position)

Looks like I'll be shopping very soon.