Hello Im new here. I really need some help. I have a 1986 JD 490 and recently i have noticed after it gets warm the machine will travel very slow and will barely steer. One side does appear to be somewhat better than the other but not much. I really dont know where to start. It doesnt quit completely it just doesnt have the drive power it should have. All other functions work fine and have normal hyd power. I read somewhere about the swivel joint may have bad seals, if so how big of a job is that? Also, is there anybody that knows where i could possibly get a hyd diagram and or shop manual for this machine, any ideas or suggestions greatly appreciated thanks.......
Indeed most likely the swivel joint seals are tired, you can usually confirm this with a heat gun or cautiously touching the swivel joint after using the tracks for a while, bypassing oil creates lots of heat. If the digging functions are still strong it's likely the pumps are fine, but other possible trouble points would be the port relief valves in the main control valve and also of course the motors themselves being tired.
Thanks lantraxco, is the swivel hard to remove? I think i will start there. Do you know where i could get a manual? Is there a way to check the pressure on travel motors?
Well, I wouldn't say easy. I haven't been around one of these (or the Hitachi equivalent) in at least twenty years so I don't remember much. Looking at Deere's online parts book I would say the top lines are hoses, but all the lower unit plumbing is hard lines so it won't be fun to deal with those. Looks like it's directly under the boom foot and probably weighs a hundred pounds give or take. Four high pressure lines and a drain I think. Other than like Ebay or something, or a Deere dealer with a large used parts system I don't know about a service manual. Manual will show the test points, pressures, procedures. Maybe somebody with recent experience will pop in and shed some light on it.
ok thanks , i plan on tearing into it in the next few days, i'll post back to let ya know what a i find