CubanB 4 #1 Posted June 22, 2020 First of all I want to thank everyone for sharing their knowledge on this site. You have helped me considerably. I picked up a low hour 520H with no attachments, mainly to pull firewood, worst case for spare parts. My primary mower is a 518H with a 48” deck. Now that I’ve cleaned up the 520H I’ve been thinking I want to move the mower to that machine. The problem is that the Hydraulic lift does not appear to be functional. I knew this when cleaning it up but didn’t really mind at the time. The lever to control the cylinder won’t even move. I don’t want to try too hard and break something off. I did change the transmission oil and filter when cleaning it and it did not change anything. It drives well and does not appear to be leaking any oil. For all I know this was never used at all on this machine. Is it possible to have the piston seize in the cylinder or have the valve lock up from lack of use? I did take a picture of the valve when I had it apart if it helps. From what I’ve gathered rebuilding the valve is just a few o rings. I’m wondering where I should start and if you guys think it’s even fixable. I appreciate the help. 1 Share this post Link to post Share on other sites
lynnmor 7,446 #2 Posted June 22, 2020 Pull the pin on the valve and see if the handle moves freely. Push and pull on the valve to see if it moves, it will take a bit of effort. You will need to drop the valve to get at the opposite end if it needs service. Share this post Link to post Share on other sites
oliver2-44 10,016 #3 Posted June 23, 2020 The valve is a good place to start. If it moves freely as indicated by Lynmor, then its time to move to the cylinder. When you changed the hydro transmission oil was it milky from water being in it. If water made its way down to the cylinder the piston could be rusted seized in place in place. Pull the pin from the lift end of the cylinder, move the lift linkage up and down to verify it is not seized in place. Start the tractor and operate the hydraulic valve and see if the cylinder will move by itself. If there is no movement, and the lift linkage is free reinstall the linkage end of the cylinder and disconnect the frame end. With the tractor off, move the hydraulic valve back and forth to releive any pressure in the cylinder. Then try to get some leverage on the implement lift and see if you can move the cylinder. If it moves a little, operate the hydraulic valve again to relieve pressure and try to move cylinder again. Repeat this process moving the cylinder back and forth to free it up. Share this post Link to post Share on other sites
CubanB 4 #4 Posted July 4, 2020 (edited) Thanks guys, I finally had time to take a look at this today, when I disconnect the linkage and pin from the valve it does indeed move freely ( the linkage that is) So it appears the valve is stuck. I tapped the valve a few times with a hammer and it did move in. I think it went all the way in. I was able to pull it out a little with some vice grips. I reconnected the linkage and tried but it wouldn’t budge. I is the next step removing the valve to service it? Am I right to assume I can not operate the machine with the valve disconnected? Update: after a bit more persuading I think I got the valve loose enough. Cycled the cylinder several times with motor running. I took a short video, the cylinder appears to be working okay, but there is a rather unpleasant sound that comes from the valve at certain points. Do I need to be worried it will fail? If it’s just the noise I can live with it. Thank again https://1drv.ms/v/s!Atlwbji1O0hyg7xI7Uino_KPmnwo4g Edited July 4, 2020 by CubanB Share this post Link to post Share on other sites
CubanB 4 #5 Posted July 4, 2020 Oliver, the trans oil wasn’t milky when I changed it, it was pretty dirty though. Share this post Link to post Share on other sites
lynnmor 7,446 #6 Posted July 4, 2020 There is probably crud inside the valve that should be removed. The valve is a simple thing, just clean it and replace the o-ring. To remove it, you can see one access hole in your photo, there is another under the battery. 7/16" socket to reach down and wrench is what you need. Share this post Link to post Share on other sites
