L4610 Hitch leaks down

[peipartsdepot]

I have a 17 year old L4610 with 3000 hours on it. The hitch leaks down and the pump will kick in every 15 - 20 seconds when the tractor is running to hold it in position. When the tractor is turned off it will leak all the way down. I have tried turning the flow knob under the seat to the closed position but it still leaks down. I have removed the flow control valve itself and replaced the O'rings but that didn't help. Any body know if I need to remove the rockshaft housing and replace the O'ring on the piston. Any help would be appreciated.

 

[rwedge]

Hi peipartsdepot, I am from Summerside, have the same problem with my B7100 HST. The 3 pt and FEL do the same thing, if U find a fix please pass it along. I welded 2 pieces of 1" angle iron about 2" long to the roll bar behind the seat and can control the hitch depth by hooking a chain from each arm to the angle iron pieces... works for me but I would like to solve the bucket bleed down.
RWedge

 

[Tooljunkie]

If you raise 3 point, close valve and it leaks down then piston seals need attention.

 

[lugbolt]

If you raise 3 point, close valve and it leaks down then piston seals need attention.

This is exactly how to test it.

If it leaks down with the valve turned off, the valve is leaking. With 3000 hours, it's likely that the piston seals are leaking.

Here's how it works. Hydraulic fluid is sent to the 3 point hitch valve-called a position control valve. It is constant flow. No pressure is made UNTIL you grab the lever to lift your implement. Once the lever is pulled, it moves a spool inside the position control valve which blocks the passage that normally allows oil to just bypass back to the sump. In turn, the oil is now directed to the lift cylinder. It is then and only then that pressure is built in the system. This is the basics of how it works, there's more to it but that's the nuts and bolts of it. If the cylinder piston seal is leaking, it will leak down. As it's leaking, it will get to a point where the other side of the same position control valve plunger will be moved to the "lift" position, causing it to apply pressure to the lift cylinder again. This cycle will repeat over and over, causing the 3 point hitch to "hunt" and/or drop.

 

[peipartsdepot]

I will try replacing the piston seals next week when I take the snowblower and cab off for the summer. I will let you know if that fixes the issue. Thanks for the input.

 

[North Idaho Wolfman]

Hi peipartsdepot, I am from Summerside, have the same problem with my B7100 HST. The 3 pt and FEL do the same thing, if U find a fix please pass it along. I welded 2 pieces of 1" angle iron about 2" long to the roll bar behind the seat and can control the hitch depth by hooking a chain from each arm to the angle iron pieces... works for me but I would like to solve the bucket bleed down.
RWedge

As far as your FEL leaking down, it could be a valve or cylinder issue.
Swap up /down lines with the roll lines and if it quits falling you have a valve issue (and on that model) it will most likely just need to be replaced, if it still falls you will need to rebuild the cylinders.

 

[peipartsdepot]

I replaced the O'ring on the hitch lift piston and while I was in there I removed the control valve and replaced the mounting o'rings on it as well, all of these o'rings were extremely square and I am surprise that the hitch was lifting at all.
Reassembled and mounted my 3pth forklift mast. Hitch has now been holding about 2000 lbs for about an hour with out dropping at all. Very pleased.

 

[RCW]

Reassembled and mounted my 3pth forklift mast. Hitch has now been holding about 2000 lbs for about an hour with out dropping at all. Very pleased.

Super - thanks for reporting back!

As a general rule - I wouldn't leave the 3ph up with weight on it, but certainly necessary to test your work!

Glad it worked!