good bucket curl but weak loader arms

[Rich Gross]

When I first got this tractor (MF 205-4) the bucket curl was good and loader arms were strong enough to make the rear end come off the ground. Now the bucket curl is still great, but the loader arms seem very weak. There are no visible hydraulic leaks anywhere. So I cleaned the hydraulic screen and changed the hydraulic oil but it still seems weak. Is it possible maybe a bad O-ring in an operator valve for the loader arms?

 

[oldnslo]

No seals in the loader valve but a couple things to check.

if quick disconnects in the line uncouple and reconnect them a partially connected QD can restrict flow and possibly cause loss of lifting capacity

is your valve direct operated by the lever or are there cables between lever and valve assembly. In either case confirm that you are getting full spool movement on the lift function. If only partially movingly this would also cause loss of lift capacity

 

[droptop]

Do your loader arms sink if left in the air overnight? You may also have bad piston seals in one (or both) cylinders.

 

[sd455dan]

When I first got this tractor (MF 205-4) the bucket curl was good and loader arms were strong enough to make the rear end come off the ground. Now the bucket curl is still great, but the loader arms seem very weak. There are no visible hydraulic leaks anywhere. So I cleaned the hydraulic screen and changed the hydraulic oil but it still seems weak. Is it possible maybe a bad O-ring in an operator valve for the loader arms?

If you have enough room on the FEL valve block and hoses are long enough you could try and switch the curl with lift connections. If the problem moves to the curl it is not the lift cylinders.

 

[Fxfymn413]

if quick disconnects in the line uncouple and reconnect them a partially connected QD can restrict flow and possibly cause loss of lifting capacity

Don't confuse flow with pressure. Low flow will slow the lift down, but eventually it will reach full pressure. In this case the complaint is weak performance which is an indicator of low(er) pressure.

My first step would be to put a pressure gauge on the loader valve's quick connect and see if you are getting the rated pressure. If so I would suspect a leaky internal seal in the cylinder.

 

[LD1]

Look up and watch some videos on how to test the cylinder seals.

Whether it leaks down overnight or not is not a test of the cylinders. That only tells you whether you have a worn valve spool. Cause worn cylinder seals won't cause it to drift down.

 

[ROUSTABOUT]

Use it and see if each feels the same temp. I'm thinking bad piston in cylinder.

 

[rScotty]

It's good to know that it used to be strong and now it isn't. Judging by the original poster's info, it sounds like we are looking for something that only shows up as being weak when trying to extend the lift arm cylinders. We ought to be able to find an easy fix for that.

It's possible that it could be a leaky piston seal in one or both lift cylinders. There are internal seals there and they do get old. That would only show up when trying to lift something. A quick test for that is to swap the hoses from bucket curl to lift cyinders.

A leak in the control valve itself would show up as the lift arms slowly falling down. The OP didn't mention that, and there aren't any replaceable seals in the control valve. So that's probably not it.

Another possibility - less likely, but real - is that most lever type control valves have a separate relief valve for both the lift and the curl circuits. So the lift circuit relief valve could be not working right. The relief valves can be swapped, but swapping the hoses above automatically swaps relief valves too.

To look at system pressure, I made up a quick connect "T" fitting with a 5000 psi pressure gauge. Cost about $50.00 to make using parts from TSC and the Ace hardware store. The gauge can be inserted into any quick disconnect line and tells you the pressure in that line. Handy for diagnosing.

good luck,
rScotty