L2550 hydraulic problem

[IanM]

I have a L2550 GST with a weak hydraulic system. The FEL will not push down with enough force to lift the front wheels off the ground and the 3 point hitch with pallet forks will only lift about 1,000 pounds when the manual says it should lift over a ton. This is not a situation that has develpoped slowly. It's been like that since I got the tractor. I have the shop manual but it doesn't list this problem in it's troubleshooting section. It has been suggested that this is due to a faulty pressure relief valve. Any suggestions as to how I can correct the problem?

Thanks.

IanM

 

[KennyV]

You should start with a check of your hydraulic system pressure. KennyV.

 

[BTDT]

Some loaders don't have down pressure. The weight of the loader bucket and arms are what makes it come down. I used to have an old ferguson with a loader and that's the way it was. It would dig below grade when you tilted the bucket down so it would dig in, but now down pressure. Do your loader lift arm cylinders have one or two hoses going to them? If just one hose going in the bottom, then all you have is lift. If hoses go into top and bottom of cylinder, then you should have up and down pressure.

 

[IanM]

Thanks for the help.

BTDT,

The loader has two hoses, top and bottom, and I get some force down but not what I should.


KennV,

This sounds like what I need to do. How would I go about checking hydraulic system pressure? I have never worked on a hydraulic system before and would like to learn more about it.

IanM

 

[KennyV]

You should start at your local dealer… They may let you borrow a pressure gage to check your system pressure. In any case if you do not have a service manual you are going to have to check with them to find out what you should be measuring. You can also buy a gage, they are not very expensive.

There will be a few variables in the mix… like type of hydraulic oil, temp of oil and system point you measure, but you should be able to get a good/bad indication if you have rear remotes…
You can measure at the loader quick disconnects and compare that reading with the system pressure, loader some loader controls have their own pressure relief valves, therefore you may be getting the loader bypass reading and not the system pressure.

Do NOT start shimming your by pass valves unless you go over all the necessary checks with someone familiar with hydraulic systems, specifically your system… There are some learn as you go things anyone can take a stab at… high pressure oil is NOT something you want to trial and error on… A good hydraulic shop can also be very helpful, In any case you will need to know what pressure you should find, … From your description it sounds like you may have low pressure, may not be a big problem but you can cause a lot of $ damage just making changes… Try to find what your system pressure is/should be and post back… KennyV.

 

[IanM]

KennyV,

Thanks for the good advice. I'll proceed carefully. I have a L2550GST shop manual and it states that the hydraulic pump is rated at 2275 psi at 2600 rpm and the relief valve should be set between 2204 and 2275 psi. I plan to test it this week. I don't have rear remotes on this machine so will start at the loader quick disconnects. The FEL, Model 84Q, I think its Gearmore, has a 'valve relief set at the factory' so I guess I won't be getting a true picture of the system. Any suggestions on where to tap into the system for a more complete check?

IanM

 

[dfkrug]

It is possible that the relief valve spring has broken. I just helped the
owner of my first L2550 check his pressure and increase his relief
(with shims) to about 2500 from 1900psi. The easiest pressure test is
done with $10 guage and the correct male metric fitting to a hose end
on the loader. That was the Kubota stock BF400G loader. Maybe you
will luck out and have JIC fittings on your aftermakt loader. The relief
valve is easy to get at in the hyd valve block on the right side of the
tractor.