I rebuilt all cylinders on my JCB 215S backhoe. I've used for over 100 hrs without any significant leakdown. Recently the Front End Loader lift control started feeling 'sticky' when moving off of zero fwd or backward. A few weeks later the FEL started leaking down fairly fast (1" per min+) whether loaded or not. I assume some loader valve seals are leaking and need replacement, but not sure which spool. Also, Does anyone know if this can be done with the valve installed, or do i have to pull it off the machine? I'll try to add a picture of the parts diagrams for all the loader valve spools
Loader Valve parts diagram pictures
I would take a look at the mrv and load hold check valves on the loader valve block by taking them out and looking at them. It would be the valve block on the right hand side on the machine frame.
I'll start checking those first, im debating ordering all the orings first before I pull them apart.
To me I guess that would depend on how much they cost and how quickly you need it. Good luck you can message me i’ll try to help if you need it.
This is the spool for the lift rams on the loader. Closest to the front of the machine. The four pictures show the different configurations you may have, but the lift spool is the same for all of them. This spool is not tied to the MRV when it is in neutral. The load hold check valves only hold the load when the spool transitions from neutral - keeps the bucket from dropping a little when you move the stick. If you are not leaking oil externally at the spool, then it’s not an O ring. The spool is metal on metal with the valve body. Since you said it was sticking, my guess is your spool is not centering because of either the linkage on top of the spool, or one of the components under it. You can work on both of these without removing the valve block. You’ll have to take some of your cab interior apart to get at the linkage and the top of your valve block. One of your new ram seals may also be leaking. Test both of them again. I’d do this first, cause it’s easy. I’ve damaged those seals while installing them. Then had to do it over again.
Thanks for the advice, I'm waiting for a good time when I won't need to use the machine for a couple weeks to tear into it. I'll try to verify if spool centering is off in the meantime.
Another vote for inspecting the newly resealed lift cylinders.
Make sure that sticking that you describe is not linkage related. There is a chance a lack of lubrication could be the cause.
I played with it some yesterday and have a few more things to try, but here's a summary: - I pulled the cover over the linkage in the cab. There doesn't appear to be any linkage sticking and the spool seems like it positively returns to center from both directions repeatedly. I don't know if this is true center however. - Sometimes the FEL seems to fall quickly while other times it nearly holds firm, it doesn't seem to be perfectly consistent even though i think the spool is in the same spot. - As the FEL is falling, i don't hear any noticable flow on the valve block. When i move the stick to lift, i hear flow start in the valve and can "balance" the FEL to not move.
- As the FEL is falling, i don't hear any noticable flow on the valve block. When i move the stick to lift, i hear flow start in the valve and can "balance" the FEL to not move.[/QUOTE] That sounds like a bad lift cylinder seal, to me. Did you test them again? I’m guessing the fittings you’ll need are British thread.
That was a good video to test the piston seals. Yes, the JCB is all BSPP 60 deg fittings. I pieced together a full set of "9030" "9033" 1/4" thru 3/4" male and female cap/plug fittings to test the piston seals now and for the future. Cheapest plugs i found were https://www.adaptall.com/products/British.php fittings ordered from HoseWarehouse.com (Murdock Industrial). I used it this weekend and had a few other observations about the leakdown: - After lifting or dropping the FEL, it only seems to leakdown a set amount (maybe 6") then seems to hold. It seems that the leak is pressurizing a volume and when the pressures equalize it stops dropping. - based on another website, i lifted the nose of the backhoe with the FEL to check 'negative' leakdown direction. It DID leakdown the opposite way as well. After i test the cylinders, maybe I look at the Load check valves? Here's the advice: "First I would put down pressure on the bucket by tipping it down and then down pressure on the boom to lift the machine up, then let go of the levers and watch. If the bucket doesn't drift the other direction, it's probably a leaking port relief and not the spool. Port reliefs only affect one direction with the valve in neutral, leaking spool usually leaks both ways. In addition usually each circuit is seperated from the spool by a load check valve which is designed to hold the load in place while you shift the valve to raise the load and the pressure builds up by the pump to overcome the static pressure created by the weight of the load and then move it. If the load check is leaking, what you get is the load drops and then goes up when you pull the lever.
Pretty sure it’s a lift cylinder. Maybe both are leaking. Test them and post the results.
Hi If you look at the picture posted check that the float function system is not falling apart all the parts at the bottom of the spool. The seals can be changed without taking the valve block out just need to remove the linkage from the top and remove the lower section should have 7/32 headed allen cap bolts on it (but make sure you lower and make safe the loader on the ground first ). You will need to remove the spool from the spring plate at the bottom to replace the seal ,this is done using a spool clamp so as not to damage the spool surface and without bending them. the seals are o rings with a wiper seal these are damaged quite easy on install we used to have a tool for inserting them but can be done without carefully.
Nuggy00, curious if you ever determined anything on this?
I haven't had time to fix anything as I've been digging. I did receive the hydraulic plugs that I ordered to test the cylinders, so I hope to do that soon. I'll post results when I tear into it