I hate my tractor - no lift

After completely rebuilding the lift, still no work. Replaced the piston o-ring and backup, replaced the o-ring (genuine CNH) on the unloader, still no lift. Unloader movement was smooth. When I put the lift cover back together, I left the unloader valve at the "pump oil into the piston" position which was forward, furthest from the plug. Adjusted linkage per the shop manual. So, when moving the control to the lift position, it should have lifted. Guess I need a pressure gauge at this point....

Then there's the generator. Another thread. Later.

This has been quite a money and labor pit......but it runs great :)
 
(quoted from post at 22:44:34 04/11/20) After completely rebuilding the lift, still no work. Replaced the piston o-ring and backup, replaced the o-ring (genuine CNH) on the unloader, still no lift. Unloader movement was smooth. When I put the lift cover back together, I left the unloader valve at the "pump oil into the piston" position which was forward, furthest from the plug. Adjusted linkage per the shop manual. So, when moving the control to the lift position, it should have lifted. Guess I need a pressure gauge at this point....

Then there's the generator. Another thread. Later.

This has been quite a money and labor pit......but it runs great :)
wo questions:
1-Did you remove the check & backpressure valves it all your work?
1- Can you hear any engine loading differences when moving the touch control lever? This would indicate a hydraulic pressure change if you can hear engine loading difference.
 
Ok, I'm over my hatred. Still like the thing. For now :)

Of couse JMOR, in my haste to get this back together since I did find the unloader stuck and thinking that was the problem, I didn't disassemble the check valving (that plug at the front, right?). No engine loading, so there is no hydraulic resistance.

I got the plug out and have no idea how to remove the innards. I grabbed the end of it with a pair of needle nose, and it won't budge. Stuck, like everything else was in this cover. Any technique or ideas on how to do it?

Larry, I did prime the pump about a week ago. Didn't think I needed to do it again so soon, but of course with the age and wear that may also be a possibility. I need to unstick the check / backpressure valve and once that's fixed, I'll check prime again.

I will say that I'm really good at removing the lift cover now :)
 
(quoted from post at 17:16:15 04/12/20) Ok, I'm over my hatred. Still like the thing. For now :)

Of couse JMOR, in my haste to get this back together since I did find the unloader stuck and thinking that was the problem, I didn't disassemble the check valving (that plug at the front, right?). No engine loading, so there is no hydraulic resistance.

I got the plug out and have no idea how to remove the innards. I grabbed the end of it with a pair of needle nose, and it won't budge. Stuck, like everything else was in this cover. Any technique or ideas on how to do it?

Larry, I did prime the pump about a week ago. Didn't think I needed to do it again so soon, but of course with the age and wear that may also be a possibility. I need to unstick the check / backpressure valve and once that's fixed, I'll check prime again.

I will say that I'm really good at removing the lift cover now :)
'm not sure what you grabbed the end of with needle nose, but this is behind the plug. If you get back to the 3rd part back from the right side of picture......, you need to be very careful, as that part has a reputation of the threaded part breaking off & leaving the remainder stuck in place. Furthermore that part is no longer available. Right portion is back pressure and I might just try to do washing instead of removal if possible. Left ball/spring/spring guide is check valve & my thoughts were that it might be stuck closed or the spring guide installed backwards, thus increasing opening pressure, BUT.....since you observed no engine loading as if pressure were topping out, I think I will call this thought a dead end. Need to get back to 'why you can't build pressure'?
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Ok got it out....this was all that was in that cavity. Ball, pilot, broken spring....looking at the manual there appears to be a bunch of other parts....do they come out from under the lift cylinder? I admit I cheated a little by just lifting the front of the cover up...

Looking wown the hole, I see what I think is the seat for the ball. Has internal threads. Is this to be pulled out? Remember reading in the archives that this seat can break and will be a real problem.

Any idea where I can get the spring without spending $30? Seems just a little steep for a spring....
mvphoto52580.jpg
 
You can do this to eliminate any thing in lift cover as a cause for no pressure, leaving only pump & over-pressure relief valve. Measure at side of hyd housing test plug or at pump (if a piston type).
SPB82ug.jpg
 
Posted before I saw your reply, JMOR. I'm with you on not wanting to break the seat, so I'll leave it alone and just try cleaning. Seems to me that it's likely with a broken spring the ball is not sealing creating the no pressure problem? I can only hope....
 
(quoted from post at 19:00:14 04/12/20) Posted before I saw your reply, JMOR. I'm with you on not wanting to break the seat, so I'll leave it alone and just try cleaning. Seems to me that it's likely with a broken spring the ball is not sealing creating the no pressure problem? I can only hope....
orry to say, but that isn't likely the problem. Even with that, it should build pressure and lift, but just not hold position. Sorry to be carrier of bad tidings.
 
Getting used to the disappointment on this tractor! I've done worse... What range pressure gauge do I need, and is the pump rebuildable, i.e. parts available? They're damned expensive used...
 
(quoted from post at 00:05:23 04/13/20) Getting used to the disappointment on this tractor! I've done worse... What range pressure gauge do I need, and is the pump rebuildable, i.e. parts available? They're damned expensive used...
000 psi. Piston type, rebuild-able, but if vane type, they are better replaced with piston or something else as they don't re-build well due to housing wear.
 
The pressure should be in the 2000 psi range,and maybe even a little higher, so I would recommend a 3000 psi gauge. testing a system with gauge that maxes out at the recommended psi of the system won't provide an accurate reading and may cause the gauge to fail if it is an inexpensive (cheap) gauge.
 
Got the lift to work. After replacing almost all of the inner O-rings, de-rusting and making adjustments, I believe the most recent issue was pump prime. After three weeks of sitting, same problem - no lift. Once again primed the pump and again the lift works. I was able to get a load on it and saw 1500 PSI. So it seems the pump makes decent pressure. What would the loss of prime be casued by? Pump rebuild in order?
It's a piston style pump....
 
Prime is lost because air has replaced oil in the suction side of pump. Where does air get in? Gaskets, seals leaking valves, etc.
Sometimes external leaks can be found visually by oily residue, but internal not.
 
Thanks JMOR....Ok - going for the rebuild of the pump which should provide the necessary pump gaskets / seals. I'll also replace manifold gaskets too and see if that solves the problem. If I missed anything, please let me know what...
 
It actually came out fairly easily. I didn't remove the seat, due to the potential breakage, and my luck with this machine so far has me avoiding any unnecessary work. I've yet to put any real weight on the lift to see if the spring and ball replacement was of any value, but a broken spring would certainly not hold it up for any period of time. I'm considering it fixed until I'm proven wrong :D
 

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