L3600 3 Point Surging

[coderbond]

I don't know if I'm describing this right or not but I'll try. I rescued a L3600-GST from a dealership that had been stripped and rebuilt it last year. Here's the thread with some background.

Basically I rebuilt the 3-Point/top plate. When I use the three point to lift stuff, mower attachments, forks, etc. it hops.

Any ideas why that would be happening and what I should try to fix it?

Thanks OTT

 

[Bulldog]

I would guess and say the 3pt is leaking down very slow and as it comes down the feedback rod tells it to lift back to the hold position. And then the cycle repeats itself and you have the hop you describe.

 

[coderbond]

Do I need to pull the top plate and adjust the cam that controls the hydraulic valves? Or are you suggesting its a seal problem?

I'll admit that portion of the shop manual that described how to set the cam was confusing.

 

[North Idaho Wolfman]

What you are describing is the same thing thousands of other people have described, it's a design defect in the valve setup on that model of tractor.
of all the articles I have read the only real fix is to install a lift valve out of a L Grand tractor.
Some have noted little improvements with adjustment and fine tuning but none have eliminated the problem.
Here is one post on it:
http://www.orangetractortalks.com/forums/showthread.php?t=17412

 

[Bulldog]

Wolfman, I don't think my 3000 suffers from the bad valve like what some of the others describe. My 3pt actually leaks down slowly and them it will raise back up. It does this worse when I have something heavy on the back like a roll of hay. It does it with other implements but not as often. What do you think?

 

[North Idaho Wolfman]

Wolfman, I don't think my 3000 suffers from the bad valve like what some of the others describe. My 3pt actually leaks down slowly and them it will raise back up. It does this worse when I have something heavy on the back like a roll of hay. It does it with other implements but not as often. What do you think?

Your L3000 has the same valve as my L3450 (perpotional valve, not stepping) and does not have a problem, with yours a couple things come to mind:
#1 Being that the feed back rod is out of adjustment, it will actually make it go down very slowly like it has a leak or issue and is bleeding down, simple adjustment will fix it.
#2 It does have a leaking piston, simple test raise it with weight, close the speed lock valve under the seat, if it drops leaking piston or leaking valve, most likely piston, but while your in there rebuild both.

 

[Bulldog]

Thanks Wolfman, I'll try that some as I can and see what it does.

 

[coderbond]

Well... That blows!

Everything on the top plate is brand new. I left an implement on it and it didn't leak down over night. For all intents and purposes it feels like its lifting up, then drops down. not dropping down and lifting up. I guess it could be a matter of perspective on where you come in to the loop. But it isn't leaking.

So basically you're saying its just the way the tractors are, no fix. Won't the constant flow of fluid through the top plate cause it to warm up?