I'm just about done rebuilding the valve block on my EX, but I'm having an issue sourcing the o-rings and backup rings for 7 of the relief valves. I think there is an omission in the parts manual. It calls out several different part numbers for each of the valves: but there is no separate parts diagram for each of these valves in the manual! There are for many of the other relief valves on this machine, I think they just screwed up. The service manual has a detailed breakdown of each valve: but once again, no part numbers. It does give me this middle finger though: The Deere dealership near me tried for a little bit to help me out, but gave up. They sent me a quote for replacement valves for $3500, but there are generics on eBay for $100 each. So what should I do? I could take apart one of the valves and try to measure the old o-rings and come up with generic replacements, but the rings are pretty brittle and cooked. I could buy a generic valve off ebay for $100 and measure all the rings off it. Maybe take it to a hydraulic shop? I don't know.
Have you tried going on the Deere parts site? A Deere 490E low serial number would be the same as a 120-2. The valve breakdown is likely in the Hitachi hydraulic component breakdown parts book.
Yup, they have pretty much the same exact drawings as I have with the same omissions. Is there a separate parts book for hydraulic components? The parts book I have has breakdowns for all the other relief valves (for instance on the swing motor), just not these. I have two parts books: "equipment components parts" and "parts catalog"
Yeah I noticed that in the Deere parts diagram, (and I kind of guessed these part numbers because there are plugs right next to them with the same sized thread), but there are an additional 6 more rings inside of each valve: