I have a Hitachi EX200-LC3, the coupler on the hydraulic oil cooler line came off while operating a week or so ago so i replaced it, a hour or so later it came off again. I decided to replace the flow controll valve in the line and the hydraulic filter thinking that was the problem. After puting it back togther i discovered the cooler was also leaking out of mutiple cores. I orderd a new cooler, $3,300.00 later after installing it figured i better check the line pressure. The pressure going into the cooler is around 35 psi under no load and when running all functions, except when i extend the stick the pressure goes up to around 140 psi and when I curle the bucket out it is at about 80 psi. I'm not sure what to look at I checked the spools and they seam fine. Any help would be great, the service manuals on Hitachi are not verry user friendly.
check if the return line from the cooler to tank is throttling somewhere
Check to make sure there isn't air getting into the system, low fluid, suction side air leak, plugged strainer, collapsed suction hose? Air being released under pressure will mess stuff up fast. The cylinders aren't settling fast are they? That's my guesses. Please let us all know what you figure out.
not sure what you mean by the cylinders aren't settling fast. checked the line and dont see any problems there. i'm thinking it must be in the controll valve, just not sure what to look at. the only time the pressure is high is when i extend the stick out or roll the bucket out. all other functions the presure is good.
Well I guess no one on here has seen this problem, so today after some more guess work I decided to call the local John Deere dealer. The service manager didn't know either he checked with all of thier techs and couldn't tell me where to look. They submitted a report to DTACK (Hitachi support) and said they would let me know in a few days. So for now i"ll just wait to see what they say.
The thermostat for the hydraulic cooler is no more than a heat actuated diverter valve. Just like the engine thermostat, when it is cold at start up, hydraulic oil returns from the control valve and either goes directly to tank or as the valve heats up, it diverts oil to the cooler then returns to tank out of the cooler. If the return pressure is high, something has got to be restricting the flow at or between the control valve and the tank. I have never seen one go bad, not saying yours wasn`t bad, but very unusual to have a problem with it.
"Cylinders settling fast" meant are the cylinders leaking down. Not likely to have anything to do with this. Did Deere think that the cooler pressures were too high? The higher pressure on those functions is due to the reverse of "pressure intensification", "flow intensification" causing the higher pressure at the cooler. If there's a return hydraulic filter, then there's probably a filter relief/bypass valve there that would be worth checking.
Thanks for all the sugestions. Greg I agree with you on the valve going bad, I changed it before checking pressures. After changing the valve I checked the line going to tank and the bypass, everything checked out good. Delmer, yes Deere said the pressure is extreamly high and no problems with the relief/bypass valves or cylinders. The strange thing is the only time the pressure is high is when you swing the stick out or bucket dump function, all other functions are ok. Deere thinks there is a problem in the main controll valve, but wanted to wait for a responce from DETACK before having me pull the valve out. I'll keep you all posted on what they say and what i find out. Thanks again for all the help.
Well I got it figured out today, I feel kind of foolish though. I called everyone I could think of to call and no one was sure what to tell me. I decided to start over on my troubleshooting like it was the fist time looking at it. I pulled the filter, the line going to the cooler, the one comming out. Nothing blocking the flow. I went back to the manual. I pulled of the cooler bypass line to check it and the cooler bypass valve. Thats were the problem was, as it turns out someone had had the controll valve out before and when the put the valve in they installed the bypass valve in backwards. I guess lesson learned again, Don't assume that parts are installed correctly by someone elses prior repair.
Hello I was looking for some help on my ex200-2 machine and saw this thread. I had some grinding problem with my pump replace the internal parts and pilot pump. Installed the pump but nothing move the complete machine was dead no response when the control levers are activated in the cab. I tried to clean as much as I could removing particles then I started to get movement from all parts but with a strong vibration. Then I notice that the return flow back to the tank is very heavy still it spill over I looked at the bypass valve from the cooler and it was ok, I removed the valve bank dismantle it and clean looking to see if something was stuck, make sure that things are moving freely the reinstall but the flow is still heavy. I am reading as hell trying to see if I will come across something that may help me. please I need some direction anyone.