Gentlemen. Thank you for the privilege of joining this forum. Been reading threads for a while and cant find a discussion on my issue. I recently purchased my first Big machine...a Liebherr LR 621c serial #278 1588 for clearing on my farm. It had a hydraulic leak into the gearbox from one of the pumps, but otherwise runs great. We drove it from my neighbors property from whom I purchased it, which was about a 1/8 mile from my farm. It drove fine. It had hydraulic fluid leaking from the dipstick and fill port connections on top of the gearbox. My grandson who is a diesel mechanic pulled the two top pumps and he replaced the rear seals and O-rings and re installed the pumps. It runs great! The boom and bucket hydraulics work well. However....the drive system hydraulics ( joystick ) are now dysfunctional. The forward travel position of the joystick causes the machine to turn right. The reverse travel position of the joystick results in a left turn. The left and right turn positions of the joystick are in operational. No response. The pumps do not whine and there are no other irregular sounds of operation? This is beyond my scope and I thought it might be... he has incorrectly reattached the hydraulic hoses? My grandson took great offense at me even suggesting that might be the problem. He has not been back to look at it, so I guess I am own my own. I have contacted the Liebherr service and parts distributorship closest to me and have been sent some of the hydraulic system drawings from the parts listings catalog. I was planning on color coding with tape all hydraulic lines from the joystick to their connection points and then verifying he reconnected them all correctly. Am I chasing my tail or what might you suggest? Is it time to call a certified Liebherr mechanic or might I have a solvable problem? Thanks for being here for us lesser trained and experienced guys.
Is it just one track that is operating on this machine? I am not really familiar with this brand. If it is just one track operating I would wonder if there are pump couplers in the gearbox that one may have been lost. I have also personally left red plastic cap/plugs in hydraulic hoses before. Those can make you rip your hair out. I wish I had some more precise info for you. Seeing as this machine may be yours for awhile, perhaps you should invest in the workshop manuals. They can be a lifesaver in situations such as this.
Thank you for responding. Both tracks are sharply responsive.. but the joystick operation is not correct. Forward travel position makes the machine turn right. Reverse travel position makes it turn left. There is no response when the joystick is positioned left or right? Could you provide any further info on how and where to obtain the workshop manuals? The Liebherr parts/service rep in my area told me there are no manuals or service books available? He has sent me several parts listing diagrams and drawings but they lack reference and detail. Just drawings with parts numbers. Thanks again for your help.
I just wanted to make a suggestion on something because I think there are 2 hoses crossed on your machine. If your machine has a counter rotate button on top of the left joystick, try pushing it down while leaning the stick right and left. If the hoses are wrong, this should make your machine go backwards and forwards.
Might want to check with a JD dealer for a manual or troubleshooting guide as some JD loaders were actually Liebherr's. 755C comes to mind. Not sure how similar they would be though.
Ok I found a hydraulic schematic for a bit smaller track loader but I think the drive system is the same. From what you are telling, the left track is doing what it should but the right track is opposite. Please switch the Z and Y hoses on the right side pump (right side as you are sitting in machine). This should solve your problem. []
I don't know if it will help or even if it is the same. This is from a Liebherr 622.
This also may help. I believe from my searches that machine uses linde pumps. Here is a link to information on just the pump for the drive unit and a picture of the Y and Z ports on said pump. http://www.hydraulik.ch/files/v170516141053/PDF-Dateien/BPV-Datenblatt.pdf
Gentlemen....Thank you to each and every one who responded to my issue. Due to your suggestions...I was able to locate and obtain copies of the Operations and Service manuals...but due to weather and illness... I have yet to be able to work on resolving the problem. I will post the outcome when I get the problem taken care of. Thanks again!
Thanks for the update. Hope you feel better soon.