Deere 3320 rockshaft/system hydralic issue

[GreatWhitehunter]

I posted this over in the deere forum but got no replies. I have a deere 3320 hydro and had a small issue while harley raking a customers lot. I was raking and lifted on the rockshaft control lever(3pt control handle) and no lifting occured. I got off the tractor and fiddle around with a few things. Such as the raise and lower speed control valve. Still no lift so I figured it was either low oil or a plugged filter. So I pulled off the power beyond inline filter(sintered) And low and beholf the center of the filter is missing ( about the size of a pea) So I hauled it home into my shop for the disection. It seemed that none of the other hydralics were affected other than the rockshaft. I took ever piece of the rockshaft system apart ( I talked to my dealer for support) and found no issues. I took the entire rock shaft pilot control valve apart and still found nothing. While I had the valve off I put air into the system and found nothing. No restrictions nothing. I then took the piston itself apart thinking there was something stuck in there. Nothing was found. So I put everything back together and was going to bring it to the dealer. Which I really didn't want to do for money reasons. So I try the rockshaft after it's back together and it works no issues. So now I'm confused and had expected to find the missing piece somewhere in the system. So I started using the tractor at my place and all seemed normal. But today I hitched up to my bushog and had to increase the rpms to get it to raise to full height. So I was using it today to do some loader work and was working on an incline. I had the rpms about 18k (which normally would would be more than enough for this task) I needed to bump the rpms up to 20k to keep a steady pace? So now I don't know what to try. I believe there's separate pumps for the hydrostatic drive and rockshaft but I believe the sump and filters,lines are common. I really need to get a game plan together and fix this thing
100%. Unfortunatly I lost my real day job last week(another story) so I really want to avoid taking this to the dealer a 100 an hour and feel capible of making the reapirs myself but I'm not sure what direction to head? I was thinking I should get a gauge and test the system pressure. Then if that's sat I've got the think it's a plugged line somewhere? So I'm looking for some suggestions and comments. Sorry for the long winded post.

Matt T.

 

[Cocre]

According to the JD 3x20 technical reference, a loss of charge pressure will cause poor transmission performance. The charge pressure is supplied through the power steering hydraulic pump. There is an inline filter before the transmission, check that (it is on the left side near the engine) Item 6 in left picture. There is also a charge pressure relief valve that may be stuck open or have that missing piece of filter in it. Item 11 in right picture.

 

[GreatWhitehunter]

Cocre, on the second pic with the relief valves where is that located on the tractor. I will check the inline filter tommorrow. Thanks for the helpful reply.

Matt

 

[Kernopelli]

I have experienced a similar issue with 2 different tractors, neither JD's though. First time was caused by a small piece of RTV that was in the control valve, the second time I figured it was probably the same thing and ended up taking everything apart as you described several times before I discovered a small piece of metal in the 3 point hydraulic relief valve, sometimes it would allow it to close, some times it allowed it to stay open, hence the inability for the 3 PH to function. Very easy fix, quite time consuming and FRUSTRATING at the time....anyway, does your 3 point have a relief specific to it? If so, might try looking there.

 

[GreatWhitehunter]

Yes it does have it's own relief but that was one of the first things I checked. The relief valve is working 100%. It's got to be down stream of the 3pt control.

Matt

 

[Cocre]

Cocre, on the second pic with the relief valves where is that located on the tractor. I will check the inline filter tommorrow. Thanks for the helpful reply.

Matt

Follow the charge pressure line back from the inline filter to the hydrostatic transmission. It is in that area. The book says to disconnect the line before removing the valve. I would think the inline filter would catch any debris before it made it to the relief valve. Unless it got trashed also.

Also, check the big suction filter too.

 

[Kernopelli]

Cocre has got the answer then. If you are absolutely positive it is upstream of what you've already looked at, you need to systematically follow the supply and check every possibility as you come to it, check its function and condition and move forward if that wasn't it.

The one thing that doesn't add up is that after you reassembled everything the system worked initially but after a little use started showing signs of a problem again. This is the same reason I had to take my system apart several times the last time I had this problem. I did the same exact thing you described... disassembly of valves, relief, speed control, small gauge wire through all orifices, spray lubricants and compressed air, etc but unfortunately it took several attempts to find the actual culprit. It may have been a separate piece that came through the system and lodged after the first round of tear down or was actually there the whole time. Hard to believe it was not there the whole time though because I never found any junk at all in the system the first time. It would work for a little bit after reassembly then stop working again. No way of knowing for certain how it went down but sounds like that may be a possibility in this case too. Not trying to be a bummer or disagreeable here, just relating a personal experience. I would first follow Cocres advise and rule out everything that hasn't already been looked at.

I agree with checking the return filter/and or screen. Been down that road myself but mine was common to the entire hydraulic system and I had symptoms with all the hydraulic systems, not just the hitch. If yours is the same set up it's not likely the problem, if you have a separate suction filter/or screen for the 3PH system then it definitely bears looking at. Sounds like you probably already checked it but did you take the speed control apart and check it too?