The fun doesn't stop. 3 point piston seals on M4900.

wheelinag

Member

Equipment
M4900
May 16, 2025
48
8
8
La Grange, TX
Well after the fun of diagnosing and replacing the hydraulic pump a couple of months ago (thanks to help from this board), I'm pretty sure my piston seals on the 3 point hydraulic piston are toast. I hadn't really used the 3 point much other than using a trench closer about 6 weeks ago. While using that, I notice the 3 point would hiccup every once in a while. I chalked it up to possibly an adjustment problem in the control linkage.

Last weekend, I put a carrier on the rear where I can put a 250 gallon IBC tote for spraying. I was only putting about 50 gallons in it, but never tried to lower or raise it until taking it off this weekend. The 3 point wouldn't even lift the carrier and pretty much empty tote, I'm guessing a few hundred pounds at the most.

The arms will barely lift themselves when the tractor is on and fall immediately when turned off. From everything I've read, the piston seals are the culprit. The parts are not expensive and doesn't look like a hard repair. A couple of questions though, anything else I should replace while I'm there? Do you have to remove the entire cover to do this? It looks like the front cover can come off and piston come out the front? I read on here that someone has done this and people have used suction cups to pull the piston out as it's floating. That was on a different model though.

As always, thanks for the help!
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TheOldHokie

Well-known member
Lifetime Member

Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Apr 6, 2021
9,998
5,327
113
Myersville, MD
windyridgefarm.us
Well after the fun of diagnosing and replacing the hydraulic pump a couple of months ago (thanks to help from this board), I'm pretty sure my piston seals on the 3 point hydraulic piston are toast. I hadn't really used the 3 point much other than using a trench closer about 6 weeks ago. While using that, I notice the 3 point would hiccup every once in a while. I chalked it up to possibly an adjustment problem in the control linkage.

Last weekend, I put a carrier on the rear where I can put a 250 gallon IBC tote for spraying. I was only putting about 50 gallons in it, but never tried to lower or raise it until taking it off this weekend. The 3 point wouldn't even lift the carrier and pretty much empty tote, I'm guessing a few hundred pounds at the most.

The arms will barely lift themselves when the tractor is on and fall immediately when turned off. From everything I've read, the piston seals are the culprit. The parts are not expensive and doesn't look like a hard repair. A couple of questions though, anything else I should replace while I'm there? Do you have to remove the entire cover to do this? It looks like the front cover can come off and piston come out the front? I read on here that someone has done this and people have used suction cups to pull the piston out as it's floating. That was on a different model though.

As always, thanks for the help!
View attachment 160399
Rsise the unloaded arms and fully close the lowering speed valve. Hang a couple hundred pounds on the arms cc snd wait. If the arms stay up the pi a tin seals are fine.

Dan
 

wheelinag

Member

Equipment
M4900
May 16, 2025
48
8
8
La Grange, TX
Rsise the unloaded arms and fully close the lowering speed valve. Hang a couple hundred pounds on the arms cc snd wait. If the arms stay up the pi a tin seals are fine.
I'll have to wait until next time I'm at the orchard, but thanks for the suggestion. What else could be the problem, position valve?
 

TheOldHokie

Well-known member
Lifetime Member

Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Apr 6, 2021
9,998
5,327
113
Myersville, MD
windyridgefarm.us
Loader works fine, picks up the tractor no problem. Hoping I don't have any pressure problems as I just put in a brand new pump a couple of months ago...
Loader is ahead of the 3pt. I think you might want to start there and follow the neutral circuit to the rear.

Dan