B7100 hydraulic issues

[TxRzrBk]

I have an early 80s b7100dt (gear driven) and I am having a couple of problems out of the Two hydraulic systems.

1) the 3 pt arms slowly lower while I am mowing. The problem seems to have been worse recently , I find I really need to raise and lower the cutter after every pass to make sure I get an even cut. The hydro oil has been changed and the filter cleaned but that didn't change anything.

2) tractor has a fel with a hydro pump driven by a shaft off the front of the motor. The fel works but lacks the strength it had a month ago, for example if I put the bucket on the ground more often than not it won't lift the front wheels off the ground. The fel hydro system uses one of the supports as an oil tank, I found the pickup line at the bottom of the tank has a screen which I cleaned. Oil level is fine . the weakness started after I used a rachet strap to pull the bottom edge of the bucket up so that I could weld a crack, not sure if this is a coinendence or what may have caused the problem

What are the possible causes of these issues and how should I go about troubleshooting them?

 

[North Idaho Wolfman]

As far as the 3 point that's an internal issue with either the valve or the piston seal, they are both in the same place, so plan on pulling them apart and rebuilding both of them at the same time.

As for the loader 2 things come to mind, #1 being that when you did what you did with the strap you blew a seal out of the piston, second would be that it too needs the loader valve rebuilt.
To see if it's a piston or a valve problem swap the 2 lines for list with the 2 lines for roll, if the problem is in the valve then the problem just moved from the arms to the bucket, if it didn't move then the problem is in the seals and you'll need to rebuild the cylinders.

 

[TxRzrBk]

Ok so on the 3pt i'll need to get into the control valve and replace seals?

On the loader, it is still fully functional just not as strong. If I move the lever several times it will actually lift the front wheel but if I grab the lever and hold it open when the loader hits the ground I hear a hiss noise in the control valve which makes me think it has something to do with pressure relief, maybe as simple as an adjustment?

 

[Dwarner]

My b7100 had the same problem with the loader hydraulics. I found that when I used a gauge to check the hydraulic pressure that my maximum pressure was around 800 psi. I had an adjustable relief valve so I cranked the pressure to the recommended pressure. The difference in operation was amazing.

 

[CJN8]

Can you post a picture of how you performed the test. I would like to test my B7200 FEL. Having trouble visualizing how and where to do the test.

 

[Dwarner]

To check the pressure I mounted the gauge inline with one of my loader lines then when the loader line is pressurized and fully retracts or extends the gauge will show the maximum line pressure.

 

[CJN8]

Got it, simple.

 

[jmccanna]

Hello,

James here - new member but owner of an 80's vintage manual 4wd B7100. I too have the hydraulic problem and can no longer lift the front end with the bucket. Your post mentioned a adjustable valve somewhere. Could you advise me where to look for that? I am also going to change the hydraulic fluid as it has gotten a bit milky. Thanks in advance.

 

[Dwarner]

My Rhino loader has a Prince loader valve which has an adjustable relief valve. The relief valve is visible above the rubber boot.