Just bought a mid 1980's John Deere 490 excavator and have some questions Im sure you all will have answers to. Two of the hydraulic rams are slightly leaking and I am curious how difficult this is to repair? I would also like to find where I could print out a maintenance and operating manuals if possible? I am very interested in putting a hydraulic or manual thumb on the machine and curious of any used equipment dealers in the Rocky Mountain area? I'll most likely have several more questions as I get into this machine, but genuinely appreciate any guidance you can offer. Thanks, Casper WY
It's a straightforward job. Just depends on whether you have or can improvise the size of tools needed. The piston nut will need a few thousand foot pounds to break loose... First thing to check is if there are any scratches on the chrome rods.
Thank you Delmer. Not sure what I would have that could put up that type of torque. Think I'll look at pulling cylinders and taking to local JD dealer to rebuild. Thank you again for your time.
Some people cut a wrench out of plate and use a pipe to turn it. A member on Kodiak island posted some nice pics of his procedure. I'd take them to a hydraulic shop over a Deere dealer, but that depends on what you have available and the cost.
If you are referring to the bucket cylinder, 10 chances outta 9 the rod is bent...if it is, your hydraulic shop may refuse to rebuild it. (Good luck!) As for a thumb, used or new, plan on spending $2k plus - including welding... As for a hydraulic thumb, very unlikely you have a port for this on that old girl...And even if you did, you'd be looking at another $2,000 for hoses and cylinder... Still worth it? If you've a tree farm like me (I have a 490D with a heavy duty Rockland stiff thumb) it may be worth it. If however, your primary use is excavating, it may be better to not invest so much in a machine that won't return all of another $2-$4 thousand? ~ Mark
TreeHogger: . Why would a reputable hydraulic shop refuse to work with a bent rod? My shop loves the challenge and when he's done things are like new. Obviously if the rod is bent 90degrees then it's worthless but a simple bent is a much cheaper fix then buying new.
Would a three position fixed pinned thumb work for you?
Excavators cylinders in that era at least usually had induction hardened rods. They would sometimes bend a bit without breaking, but straightening in a press was certain to result in a shattering experience.
Maddog, Lantraxco, I have heard both successes, and 'no way will I try and straighten it'... I have no personal experience... What I think I am discerning, is from the guys who 'try' and straighten them, their position is that 'it'll be close enough, and the seal will fail prematurely, but hey, better than trying to find a used one for a grand'... Make sense, thoughts?
If it's not induction hardened and not too badly bent, sure you can usually straighten them. My experience with the hardened rods is that if it's bent enough to cause a problem with the piston and/or seals, trying to straighten it will either cause it to snap in two on the press or very shortly after it's put back into service, and also can cause cracks in the chrome. If you have to grind/chrome/regrind anyway, you're way better off just replacing the rod in the first place. My opinion only, YMMV (your mileage may vary)
Agreed, thanks for the input Lantraxco and TreeHogger. Just like with many things it depends on the specifics.
Also that d model does have an extra spool for the thumb.
Hi Typ4 - always look forward to your posts... Do you mean to say that my 490D has the port under the house that I could use for a dozer blade, or just an available spool for a thumb?? Thanks! Mark