L3901 3 point issue

[OldcrowP51]

I noticed the 3 point on the L3901 oscillates when at idle no implements attached.
Also noticed with tractor off the 3 point drops with the control lever in up position.

 

[North Idaho Wolfman]

You need to consult the WSM on how to test it.
Sounds like you could have a problem with the three point piston seals.

 

[TheOldHokie]

You need to consult the WSM on how to test it.
Sounds like you could have a problem with the three point piston seals.

Almost certainly the problem.

Dan

 

[OldcrowP51]

I did this test and 3 point stays up with the flow control valve closed (in all the way in) and the tractor off.
Could air in the system cause the issue?
I recently had a line off.

 

[TheOldHokie]

I did this test and 3 point stays up with the flow control valve closed (in all the way in) and the tractor off.
Could air in the system cause the issue?
I recently had a line off.

View attachment 173103

I am confused. You raised the lift, closed the lowering speed valve, shut the engine off, and the lift stayed up?

Dan

 

[OldcrowP51]

I am confused. You raised the lift, closed the lowering speed valve, shut the engine off, and the lift stayed up?

Dan

Correct

 

[TheOldHokie]

Correct

But if you raise the lift, leave the lowering speed valve open, and shut off the engine the lift drops?

Dan

 

[OldcrowP51]

But if you raise the lift, leave the lowering speed valve open, and shut off the engine the lift drops?

Dan

Correct

Also, With the tractor running the 3 point will oscillate (move up/down about an inch)
Rapidly with flow control valve open.
It will calm down as you close the flow control valve.

 

[OldcrowP51]

I think I have it figured out.
Looking at hose connections on the tractor the upper right is supply hose (orange dot).
Which goes to the P (pressure) port on the loader valve (also marked orange paint)

The upper left hose is return (green dot).
it comes from the BY (beyond) port on the loader valve (also marked green paint).

Is this correct?
I want to make sure I have direction of flow correct.

 

[TheOldHokie]

I think I have it figured out.
Looking at hose connections on the tractor the upper right is supply hose (orange dot).
Which goes to the P (pressure) port on the loader valve (also marked orange paint)

The upper left hose is return (green dot).
it comes from the BY (beyond) port on the loader valve (also marked green paint).

Is this correct?
I want to make sure I have direction of flow correct.

View attachment 173106 View attachment 173107

Thats correct but I dont see the relevsnce to your 3pt questiin

Based on the behavior you are describing it sounds like the check valve in the lowering speed valve is leaking. The exact details of that circuit are not clear in my head. I will review the schematic and post a better answer shortly.

Dan

 

[TheOldHokie]

Here is the lift circuit schematic for the L3901. The two check valves I have highlighted in red prevent reverse flow through the position control valves. If the lift holds with the lowering speed valve closed and leaks down when its open one or both of those checks is likely leaking allowing reverse flow through the position control valve. The oscillating behavior is the position control feedback sensing the drift and correcting by commanding lift,

Dan

 

[OldcrowP51]

Thats correct but I dont see the relevsnce to your 3pt questiin

Based on the behavior you are describing it sounds like the check valve in the lowering speed valve is leaking. The exact details of that circuit are not clear in my head. I will review the schematic and post a better answer shortly.

Dan

This is going to get real confusing but hear me out. I like to learn and maybe someone can learn from my experience.
I bought my L3901 summer of 2021.
one of the first things I did was install a Land Pride third function valve for a grapple.
I hooked it up exactly per the instructions tying it into the power beyond line between the loader valve and tractor.
I noticed afterwards that the hoses connecting to the third function block were backwards (in the outlet and out the inlet) but everything worked so left it.
This weekend I’m tying in a 3 spool control valve for rear remotes and tyed it in between the 3rd function valve and tractor.
Since I had to run hoses I corrected the error on the 3rd function block (in the inlet, out the outlet)
This is when things went wrong.
I put it back the way they were and all works as should.

 

[TheOldHokie]

This is going to get real confusing but hear me out. I like to learn and maybe someone can learn from my experience.
I bought my L3901 summer of 2021.
one of the first things I did was install a Land Pride third function valve for a grapple.
I hooked it up exactly per the instructions tying it into the power beyond line between the loader valve and tractor.
I noticed afterwards that the hoses connecting to the third function block were backwards (in the outlet and out the inlet) but everything worked so left it.
This weekend I’m tying in a 3 spool control valve for rear remotes and tyed it in between the 3rd function valve and tractor.
Since I had to run hoses I corrected the error on the 3rd function block (in the inlet, out the outlet)
This is when things went wrong.
I put it back the way they were and all works as should.

Should make zero difference. Something else is going on.The third function valve will work if hooked up backwards and at one time Landpride instructions told you to hook it up backwards

Dan