John Deere 2040 Hydraulic issues

Hoping someone here can point me in the right direction. I bought this tractor not running a few years ago, as a project, and I've hit a road block that has me stumped. The tractor is the smaller 3 cylinder diesel engine, pre-266,000 serial number, open center hydraulics. After running the tractor for 20-30 minutes, the hydraulic lines running to and from the power steering and pressure relief valve get burning hot. If I continue to use the tractor, eventually the steering column and/or the pressure relief valve being to squeal. What I find puzzling is the heat seems to originate on the low pressure return line (Key 27) from the relief valve that T's back into the charge pump line. I originally suspected the steering column, as a high pressure leak seems to be a common issue but the steering wheel seems to work fine, no oil out the top, very light to turn in both directions, and does not creep on its own. So, I tore apart the relief valve. The valve (Key 9 and seat 10) was slightly marred up and might have been the issue, so I bought a replacement, and the problem is still present. At this point I'm out of ideas as to what the issue could be. Could it still be a high pressure leak inside the steering column causing the heat in the return line from the pressure relief? Unfortunately I don't have a pressure gage to test the relief pressure, does anyone have recommendations for building one or purchasing one? Any ideas would be appreciated, I've been a long time reader, first time poster.

Welcome to YT
Since on open center hyd system oil just circulates through system under low pressure I think steering valve isn't the oil heating problem. Does 3 pt hitch operate correctly? Is tractor equipped with a frt end loader?

I'm really wondering if somewhere along the line some closed center componants may of been added in by mistake ?

The tractor does have a JD 145 FEL, which works fine. The 3pt works fine, I don't see or hear any blow-by in the rockshaft housing, remotes work fine. The FEL is plumbed into a block/spool added to the service remotes block with all quick disconnect fittings. Two hoses with QD's come off of the remote block and go to the valves of the FEL and one main hose comes off the FEL valves and dumps oil back into the case near the hyd. oil fill cap. The plumbing looks professional/factory, there is no way you can cross any of the lines when installing the FEL.

Mike M. I haven't ruled that out. I don't know how one would go about seeing if the steering column is OC or CC. I can try to find the casting number on the steering column and see if it matches JD parts. If the steering column is CC, and I cracked open the low pressure return hyd. line, It would be hard to know for sure if the column is CC or OC, because I'd just get fluid that sits in the steering box cavity, when in a CC their would be no fluid coming out until I spun the steering wheel.

Does FEL have 2 or 3 supply hoses plus the 4 bucket/boom hoses? Photo below shows how JD engineers thought FEL valve should be attached to OC hyd system. What is the steering housing cast #?

TX Jim, That schematic is the exact setup of my FEL. It is two Supply hoses to the FEL valves, and a return line to the case. When I take the FEL off of the tractor, I connect the hose (key 17) with QD to
return QD (Key 5, in upper left hand corner of schematic) so I don't deadhead that circuit.

I will check the cast # when I get home tonight. Will the part numbers be the same as cast numbers? JD parts shows part number AT23175 for the housing on early model OC's and AL31515 for later model CC's
housings. By looking at the diagrams of each house, they look identical.

Okay as best I can tell, The casting number on the steering column reads T25295 then a one inch gap and then T (or Y) 29389 towards the bottom of the column...

Well I'm confused because the casting # T25295 is listed in 1020 parts catalog # 970 plus other utility tractor PC's which is for closed center hyd system but it's also listed in 3 cyl 820,830 & 2040 parts catalog for open-center steering. Older 1020/2020 with open center steering utilized a PS housing with a different casting #(T22829). I'm struggling to comprehend how same PS housing can be utilized for both open & closed center hyd's.

(quoted from post at 04:16:06 08/04/18)
Well I'm confused because the casting # T25295 is listed in 1020 parts catalog # 970 plus other utility tractor PC's which is for closed center hyd system but it's also listed in 3 cyl 820,830 & 2040 parts catalog for open-center steering. Older 1020/2020 with open center steering utilized a PS housing with a different casting #(T22829). I'm struggling to comprehend how same PS housing can be utilized for both open & closed center hyd's.

Click to expand...

My only guess, and this is just a guess, is that Deere used the same casting, with different valve stacks for OC and CC models. Casting design is expensive and time consuming, while casting manufacturing is dirt cheap once the R&D has been done.

I'm wondering if I disassemble the steering column, I may find a stuck valve of some sort, creating a CC circuit.

You're correct in the fact that the valves in valve housing have different part #s for OC & CC PS systems

Okay, another question. I've disassembled the steering column. I found that a valve in each valve block was stuck open. I pounded out the valves and cleaned the bores out as best I could. I'll take some super fine sandpaper and clean them out better before I reassemble everything. In the process of all of this I broke a valve spring C-clip. I got onto JD parts to figure out what the part number is, and can't find this C-clip in the parts diagram or parts list anywhere. I looked at the Closed center version diagram, and it doesn't appear to have any of these valves inside of it. So is this a JD engineering/schematic snaffoo or have I got an entirely wrong steering column? Attached is a picture of the broken disassembled valve/spring with the remnants of the c-clip. And another picture of an intact C-clip.

This appears to be the correct steering column. Although the diagram of the valves in question appear to be lacking, as they aren't shown.