John Deere 830 Rockshaft Lifting Power Problems

[Kickford]

Hello all,

I have been having hydraulic issues with my 830 JD 3 point lifting power this spring.
How it started was I dropped the 3 point arms with a box blade too hard last year and it ended up breaking the cam follower tip that links to the rockshaft linkage inside the top cylinder housing. This caused the 3 point to raise to full up until I set the LD to L and I could run like this for a while, till this year.
I bought a new cam follower and installed it thinking this would cure my entire problem. It did kind of. I can control the arms perfectly up and down without the box blade on. Up and down and the different LD settings all respond really well. But when I attach a heavy implement it can't lift them off the ground or just barely. I have a front end loader and it works fine on the same pressure line as the RS.
What I have checked on the hydraulics is. New oil, Filter, screen, checked the filter bypass valve, dump valve, pressure relief, rate of drop adjustment under the seat. All the linkages and springs in the RS housing when removed look great. I have adjusted the cam follower to the JD tech manual and also the RS neutral positions. Nothing seems to increase lifting power. The large cam follower arm and associated load control shaft connection to it.
Things I have not checked. Transmission pressure relief, RS actual guaged pressure, the thermal relief valve on the lift cylinder housing, or the RS lift cylinder and piston seal itself.
I am going to use a scope to watch the lift cylinder rod side for possible blow by today through the fill cap. And I'm also going to check the RS hydraulic pressure with a guage on the test port asap.
When I tilt the loader bucket back to just dead head it, the main pressure relief opens as it should and as soon as I let off quickly with my 3 point lift lever already in the full up position, it will start to lift a heavy implement about an inch each time and hold it in relief and let off quick. Probably due to shocking the hydraulic line pressure a smidge during let off? When I finally get a heavy implement up off the ground decent, it will hold it all day long.
I am thinking at this point should I rebuild the RS cylinder and or replace the thermal relief if I find out the pressure check to the RS test port not to be acceptable?
Any advise would be greatly appreciated.
Thanks in advance,
Mike

 

[Tx Jim]

With hyd oil at operating temp look inside open hyd filler hole behind seat for spraying oil. Spraying oil would indicate leaking rockshaft control valve/piston seals or possibly leaking thermal relief valve. Have you adjusted bolt(item 11) that limits arm movement?

 

[Vigo327]

I haven’t looked at any diagrams yet so this is a shot in the dark but I do know in general that when you let pistons travel outside their normal range of motion you typically end up scraping your sealing rings over some built up junk on the cylinder walls that was allowed to build up over time because the rings don’t sweep that area. This can damage the sealing rings. I dont understand from ypur description whether the broken follower would allow the piston to rise higher than normal, so.. shot in the dark.

This is a common reason why brake master cylinders often fail shortly afterward of a leak letting them run dry and be pushed all the way to the bottom when they haven’t touched those spots in years or ever before, for example.

Being able to hold weight up suggests the piston seals are ok, though. In order for the piston to have weak apply but full holding youd probably have to have a pressure leak before the valve, but since nothing is puddling on the ground it would have to leak back into tank. So i suggest looking at parts diagram for any pressure seals in the valve housing that could leak into tank if they failed.

 

[Kickford]

I haven’t looked at any diagrams yet so this is a shot in the dark but I do know in general that when you let pistons travel outside their normal range of motion you typically end up scraping your sealing rings over some built up junk on the cylinder walls that was allowed to build up over time because the rings don’t sweep that area. This can damage the sealing rings. I dont understand from ypur description whether the broken follower would allow the piston to rise higher than normal, so.. shot in the dark.

This is a common reason why brake master cylinders often fail shortly afterward of a leak letting them run dry and be pushed all the way to the bottom when they haven’t touched those spots in years or ever before, for example.

Being able to hold weight up suggests the piston seals are ok, though. In order for the piston to have weak apply but full holding youd probably have to have a pressure leak before the valve, but since nothing is puddling on the ground it would have to leak back into tank. So i suggest looking at parts diagram for any pressure seals in the valve housing that could leak into tank if they failed.

Thanks for the reply.

I am not sure why the lift arms went all the way up but right after I dropped a box blade too hard full of dirt to knock it out.
It immediately went as far up as it could physically go.
I shut the tractor off immediately because I thought it would break something else. Not knowing about that overtravel stop linkage.
Then I set the RS LD adjustment to L and was able to lower and raise it after that setting. None of the other RS settings would allow it to raise. Now after installing a new cam follower it's almost no power to lift. I did not change the washer between the housing and the base port. Im thinking this isn't helping. Got one coming.
The piston overtravel damaging the seal makes total sense.
After looking into the fill hole I could view about a drop a second coming out of the lower portion of the cylinder bore with a scope and the lift lever in the up position. Seemed like not enough to kill the lifting power but I'm no expert at all.
I was telling Txjim about all this along with the fact that inside the RS access opening I could view a steady stream of oil draining from the bottom of the RS valve casting. In image.
When I would drop the lever much more would run off that valve casting area. Rate of drop valve?
Today I eliminated the front end loader being a potential pressure discharge issue by capping the lines to it. No change.
Checked the dump valve, Filter bypass, filter and screen, etc
I'm at a point now it's time to order the RS fill seal kit, housing washer and piston ring today.
I am not certain about the thermal pressure valve yet if it's needed. But I plan on checking its cracking pressure after I remove it.
I have a hydraulic pressure test kit coming to check different areas.
I am a DIY'r and if I can fix it I'll do it and learn something in the process. OCD helps also.

Any advice is extremely helpful at this point.

Thanks again in advance

 

[Tx Jim]

Repair obvious internal hyd leak, adjust 3pt control mechanism as outlined in JD tech manual then report back with results.

 

[Kickford]

Will do sir,
When my parts arrive I'll get back. I hate it when threads like this just end with no fix results.
Thanks

 

[Kickford]

So there were several worn items. And I've isolated the two main culprits causing the lifting problem. When I took the rockshaft itself off the housing to install all new seals, I found a weak oring in the lift cylinder but a perfect bore, slightly damaged outer oring seals in the lift and lower control valves. They were much softer type of orings than the new harder material JD I installed. The old ones were probably cut slightly from forcing those end keepers in without making sure the orings were tucked well into the grooves.
But one smoking gun was when I removed the rockshaft thermal pressure relief, I was able to look through it and when took it apart I found there was no ball inside the check!!! So this was rebuilt at some point as the RS cylinder had a yellow number painted on its exterior. So who knows what happened.
I replaced the ball and set the relief at 3200 psi.
The other thing is that when I got this all back together it worked better than before the RS repair, with more raise speed and no implement, but not quite right in lift power with an implement. So I decided to unhook just the loader return to tank line again and pow!!! I got better RS lifting power than I've ever had.
So the loader pressure check/relief was also contributing part of this power loss issue along with the RS thermal pressure relief missing the check ball. That's why I seen oil leaking inside always.
Kind of I like I stated previously, when I would dead head the loader bucket tilt, and the RS lever was in the full up position then I let off on the loader quickly the 3 point arms would lift for a split second with a full weighted implement. It must be partially leaking around the pressure relief/check valve of the loader to tank when the loader was not moving and when the loader valve was at relieving pressure and I let off immediately the RS would raise slightly.
So now with everything rebuilt on the RS and I run the RS lever up with just vthe loader return tank line disconnected, I see that return line jump for a split second and then relax, as if it's trying to relieve the all pressure through the loader return line with the return line connector disconnected.
So in the end, this was a true combination of two major pressure relief problems.
I believe the part in the diagram is a check/pressure relief combination in the valve body of the loader, I will investigate it next. Or just replace the entire loader valve, which is probably what I should do as it's probably original. Any suggestions on what valve would be recommended would be great.

With an open center hydraulic system in this tractor and loader how do they prevent affecting each other being open centered? I thought this meant there was constant return to tank when in neutral on the valves. So it appears that the loader is always returning fluid to tank in neutral, but this is dropping my RS lift pressure? Does this open center loader have a pressure control/check valve to close it off when flow increases to the RS?

Thanks for all your help,

Take care
Mike

 

[Tx Jim]

JD 820, 830 & early serial # 2040 have unique hyd systems compared to other JD tractor models. Is your tractor & loader hyd system attached to tractor utilizing a hyd block(item 28)?

 

[Kickford]

Eureka!!!

This took some time to figure out. Something this ridiculous was causing a big part of my 3 point lift problem and it was in the original gresen loader valve. This broken seal goes inside the power beyond sleeve on the left side of the loader valve. There are two pressure inlets on this system and one return to tank. This internal seal closes off another oil chamber inside the loader valve. As soon as I put a new internal oring on this power beyond sleeve, the 3 point worked perfectly.
When the tractor is running, and I'm moving the bucket up or down and let off the valve to neutral, now you can hear the pump load for a split second and then quiet right down like no load until I move the three point or another hydraulic valve.
The rockshaft three point lift works better than ever! What a journey.

For anyone who might run into this problem I hope this helps!!

 

[Kickford]

JD 820, 830 & early serial # 2040 have unique hyd systems compared to other JD tractor models. Is your tractor & loader hyd system attached to tractor utilizing a hyd block(item 28)?

Yes it has pretty much everything in the picture you sent.