Thomas Martin
Member
Been trying to get signed up on the board for a bit with out success but finally got it accomplished today! We are building a 20 acre lake ourselves and bought a couple 623B's and a 65D Challenger with an 18 yard CEPCO pan to move dirt with. Had a multitude of hyd hose issues on the 623's at the start, finally just replaced most every hose in and around the neck area and started to get some up time. One of the machines SN46P02024 we are having issues with the floor wanting to go back and the elevator chain stalling. We looked at relief valves and most seem to be good, verified the spring pressures in the valves are correct. We got a shop manual when we bought the 623's. The one relief I think could be part of the problem is the one in the control valve/spool valve/the one your levers at the seat connect to. I removed it the other day and the valve as it is referred to in the book, looks like a top like you played with as a kid that you would spin, has some wear on it, fairly distinct. I lapped it while was out to try and make it seat better and checked the spring seat pressure. Book calls for around 52 pounds when compressed to 1.39''. My spring had this but someone had previously shimmed it with around .200'' shims. When putting them on the spring and compressing to 1.39'' I was around 90 pounds. Previous owner mentioned floor and other items didn't want to work well after machines got hot so I am guessing someone shimmed the spring trying to gain performance when hot. I think this relief will affect both the elevator and floor. Didn't seem to help any after putting it back together and leaving shims. The floor circuit is making 2500 psi when machine first starts up and the hotter the oil gets the pressure starts dropping and will get down to 1500 psi or some times less. Hyd oil temps are running to high, if it is 90+ outside the oil temp will climb to 180-190. Around 165 degrees pressure starts going down. I have cleaned the radiator and oil cooler. Temps were hitting 200 before cleaning. I have a new relief set up to put in the control valve but not done it yet. My thoughts are the valve in the relief is worn and letting oil past and is causing the relief to open which can super heat the oil as well. We did replace the cartridges in the smaller hyd pump which is what supplies these circuits so we know the pump is good. If we could keep oil temps down in the 160 range things would be pretty good or at least a lot better but I think there are issues somewhere else. The book speaks of 1st forward and 2nd forward speed on the elevator. One speed is all we ever see for forward, I am wondering is we do have the 2 speed if there isn't something wrong in the spool not letting it happen, I can feel a bit of a detent in one spot using the lever but elevator doesn't move. If we should have 2 speed and it isn't whatever is keeping this from happening could be part of the weak elevator chain performance. Sorry for the long 1st post, it has been building up inside me for over a month as I tried to get signed on to the board. I have many other questions but will stop here for now! The other 623 SN is 46P401, it is suppose to be a 1974 model and the other around an 84.