Sundancekid
09-18-2007, 10:38 PM
I'm new to this site and I have to say there's alot of good info out there. Nice job to everyone that contributes. I hope that I can get help with a problem I'm having with my skidsteer. Here's a little back ground on what I have. 1997 John Deere 4475, 2550 hours. I've had it for about 4 months and use it for personal use on my ranch. About a month ago I started noticing some hiccups it operating it. There's alot of factors on whats going on so please bear with me.
First thing was the hydraulics seemed to be spongy as if there was air in the system. but to come to find out that it has a self bleeding system and the oil in the tank looks good (no foam) so I crossed that off my list. Changed the hydro filter but that didn't fix it.
Then more symptoms started showing up. When I'm driving it there seems to be a pulsing action action it the sticks. The longer I use it and the harder I dig or push with it the worse it gets. ( when I'm done it feels like I got the crap beat out out of me). I first thought I was causing the pulsing by jerking the controls back and forth when I was hitting hard spots so I braced my arms and just used my thumbs to push on the sticks and I can feel the surging action.
Another symptom is with the bucket and lift arms. If I pick up a load and raise it a little for travel it seems that when I hit a bump the arms move up and down as if theres air in the system making them spongy. Also if I raise the arms and stop and the go to raise it up higher they will drop an inch or two then start to go up. The bucket does the same thing but not as bad. ( I don't know if there's hydraulic locks it the system to keep it stable or not).
I pick up a tech manual for it and started going through it but not sure were to start. I don't have a set of test gauges handy but I'm looking at putting something together.
Mine has a front and rear piston pump with a charge pump all mounted in line. The way I understand it is the charge pump pulls the oil from the tank and keeps a constant pressure to the piston pumps in turn runs the hydraulics. (please correct me if I'm wrong)
I'm not sure if I have a pump going bad (if one pump is bad would it affect the hole system or just certain portions) or maybe the relief valve is weak. That"s why I've come to you all for some help and advice.
Another point is if possibly the charge pump is going bad and not keeping good pressure against the piston pumps.
Thanks in advance for any comments.
First thing was the hydraulics seemed to be spongy as if there was air in the system. but to come to find out that it has a self bleeding system and the oil in the tank looks good (no foam) so I crossed that off my list. Changed the hydro filter but that didn't fix it.
Then more symptoms started showing up. When I'm driving it there seems to be a pulsing action action it the sticks. The longer I use it and the harder I dig or push with it the worse it gets. ( when I'm done it feels like I got the crap beat out out of me). I first thought I was causing the pulsing by jerking the controls back and forth when I was hitting hard spots so I braced my arms and just used my thumbs to push on the sticks and I can feel the surging action.
Another symptom is with the bucket and lift arms. If I pick up a load and raise it a little for travel it seems that when I hit a bump the arms move up and down as if theres air in the system making them spongy. Also if I raise the arms and stop and the go to raise it up higher they will drop an inch or two then start to go up. The bucket does the same thing but not as bad. ( I don't know if there's hydraulic locks it the system to keep it stable or not).
I pick up a tech manual for it and started going through it but not sure were to start. I don't have a set of test gauges handy but I'm looking at putting something together.
Mine has a front and rear piston pump with a charge pump all mounted in line. The way I understand it is the charge pump pulls the oil from the tank and keeps a constant pressure to the piston pumps in turn runs the hydraulics. (please correct me if I'm wrong)
I'm not sure if I have a pump going bad (if one pump is bad would it affect the hole system or just certain portions) or maybe the relief valve is weak. That"s why I've come to you all for some help and advice.
Another point is if possibly the charge pump is going bad and not keeping good pressure against the piston pumps.
Thanks in advance for any comments.