Need help with hydraulic system.

lhfarm · Aug 20, 2005

My son and I are restoring a 1947 Willys Jeep as a farm jeep. It has a PTO and 3pt lift. You can read about it here. We just installed a new (used) pump. I changed the hydraulic fluid, replacing it with ATF. The ram won't extend more than a couple of inches, even with no load. It should extend at least 6". Is it possilbe I have an air-lock?

Do I need to give more details on the setup or is there a standard procedure for bleeding a system?

Thanks,

beenthere · Aug 20, 2005

Usually the air in the hyd system will find a way out by the seals in the ram. Not a need to 'bleed' it or 'burp' it.

Have you put a pressure gage in the pressure line to measure the pump pressure? Sounds like it isn't pumping, but if you know its putting out the psi you expect, then it may be in the spool in the control valve.

lhfarm · Aug 20, 2005

( Usually the air in the hyd system will find a way out by the seals in the ram. Not a need to 'bleed' it or 'burp' it.

Have you put a pressure gage in the pressure line to measure the pump pressure? Sounds like it isn't pumping, but if you know its putting out the psi you expect, then it may be in the spool in the control valve. )

I'll have to acquire a guage. Since the spool valve is 58 years old and has lived under a jeep all that time, that might be the problem. The control valve is mount on the reservior and I doubt I can find anyone to work on it. /forums/images/graemlins/tongue.gif

Thanks for the reply. I'll keep you posted on the progess.

beenthere · Aug 20, 2005

I can't say for sure, but I would try to get the spool out and just see if the 0-rings might need replacing. I suspect they have either 0-rings or some type of packing or rubber washer in there.

I gather it is a one-way ram you are pushing out, and the weight of the 3pt, or a spring, to return it?

Are you serious about farming with this jeep? or restoring it for mostly looks, nostalgia or the novelty?

Bully · Aug 20, 2005

With the O-rings blown out, you could be pressurizing both sides of the ram. Also if the return is plugged, the movement you are getting could be just the compression of air on the opposite side of the cylinder.

lhfarm · Aug 21, 2005

( I gather it is a one-way ram you are pushing out, and the weight of the 3pt, or a spring, to return it?

Are you serious about farming with this jeep? or restoring it for mostly looks, nostalgia or the novelty?
)
It is a one-way ram, but does have a return port that is attached to top of the reservoir. The ram pushes out and forces the lift arms up. The weight of the implement pushes the piston back.

The ram case was rusted through and I had the ram rebuilt, an expenisve job. So I am assuming it is OK and the pump should have more pressure than the original crank pump. So I am beginning to think it may be the spool valve.

The jeep will be for show, except for the occasional light bush hogging. We have two jeeps. The lift is on a rust bucket that we use for pulling wagons and hauling tools around. We are doing a frame-up restore of a '49 that will get the lift.

Thanks of the suggestions. Guess I will learn about rebuilding spool valves.