Have a Hyundai R290LC-9 thats experiencing some crazy problems. All hydraulic functions (stick, boom, travel) operate albeit slowly, UNLESS you hold the right stick to the left (bucket closed/in). When you hold the stick to the left, all hydraulic functions (stick, boom, travel) work normally. Only one fault code showing HCESPN 120, FMI 4. I've done the normal things, check fluid, change filters, no change in performance. Any help would be appreciated - this one has me scratching my head. Thanks all!
Here is a long shot. Try looking for the check valve "Ck2" I have pointed out in the pdf attached. It is located between the main Bucket A and B ports on the main control valve. Remove and check that this valve is not stuck open with contamination or has been incorrectly assembled. Best regards
Are you sure it is the same machine OP is talking about? Or I am looking at the wrong diagram of R290LC-9.
It is actually CK 1, it’s showing on the side of the MCV behind auxiliary section. If that one blown - NFC pressure will not be dropping for anything but the bucket spool cutting sensing gallery. It may work, but one pump will supply both sides - so it’ll work but slow. Why it is only bucket one way - I don’t know at this point
OK, only one side of the bucket pilot control activates the P2 pump “pump bypass cut”, that’s port Pa5 - bucket curl. So I was wrong - in this condition both pumps will get NFC pressure dropped and both pumps will up-stroke. Pretty much blow or stuck open Ck1 will cause the condition you described. Let me try and find picture for you.
This is interesting! So CK 2 is a port. Check valve is actually inside of the port adapter shown as CK1 ( not inside the MCV), and two of them connected with the outside line.
Looks like functionally whatever I and Kobe Steel is saying it’s the same. The only his diagram showing that check valve is in the adapter of the CK2 port, and mine shows that check valve is in the port adapter of the CK1 port. You gonna have to see how it is on your machine
These things confusing as heck. Some things showing on my daigram but not on Kobe’s and some otherwise. On picture of mine it’s actually shows check valve in the CK2 port ( like Kobe said), but it is not that way on my diagram. But here’s a kicker - none of the pictures show the line that goes in between those ports but there is a line, probably steel one also. You’ll need to remove it, and whichever port has that long hex looking thingy - that your culprit. Something either shattered in to pieces on the inside, or stuck open. I circled both ports, there should be I line connecting both of them.
Perfect - I too was running down the Hydraulic schematics and struggling to find the crossover point! I did replace the pump pressure sensor and finally have hydraulic pressure in range for both pumps. It obv didnt help with the slow controls issue I am having. I am gonna check this out and report back. Thank you so much for this!
Wanted to follow-up - You both were spot on with the check valve being bad. Pulled it, and found the internal clapper was broke into two pieces, one being turned around and preventing the valve from "checking". Cant thank you both enough for the assist. Pics attached
Hello, i have a frustrating issue that has happened on my Hyundai R330 LC9S. The arm roll in function has become very slow and appears to be fighting itself on the roll in function. Every other function works perfectly including arm roll out. both P1 and P2 pressures on the dash diagnostics show it working at full pressure when rolling in even if the bucket is out the ground and no load. i suspect a valve is preventing exhaust to the return line so it if fighting itself to roll in. the arm function has adjustable regen settings but playing about with these makes no difference. if i roll the arm in from a high horizontal position it will come in quick as normal until it now requires the hydraulic system to take over rather than gravity. this implies that the cylinder make up valves are working ok. Any advice on where to start would be appreciated.
r290 lc-9 issue here.. **Thank you to the experts who provide the advice & hydraulic schematics and diagrams above. Still not sure which website to get the service book off of, many of the online stores seem sketchy. Had some trash in the main relief valve that caused the machine to barely operate. Changed that out and almost all functionality is back. Left side tracking is still slow, and suspect there is trash in there too but am unsure where to look on the valve block. Final drives look good w/ clean oil. Any direction would be appreciated! Apparently the machine had the hydraulic pump fail prior to my purchase and the system wasn't properly flushed. Has new / rebuilt pump and no debris in the oil tank or filters that I see. Has worked for 2+ years on the farm.
Need to correct what I wrote above if anyone has suggestions... Left track is strong / normal, boom & bucket are normal, right track barely moves, swing barely moves. Both move almost normal if left track is engaged.