Jubilee hydraulic problem - still

[Al in Il.]

Iv'e posted in the recent past about my 1953 Jubilee hydraulic problems. Here's a recap from what Iv'e done and where I'm at:

The 3 point always bobbed a little and dropped down after shutting off in the up position - it's did it for years, Iv'e owned it for 29 years. Never an issue really for me. Recently it was slow to raise, I saw with an inspection mirror the safety valve was leaking. Took the top cover off and noticed the valve had backed out/unscrewed from the housing. I screwed it back in with no leak (and replaced the hydraulic piston O ring and leather washer). The back pressure valve gasket fell out making it leak in another spot of course. Replaced the gasket and tried again. This time I had foamy hydraulic oil - had an air leak on the suction line. I fixed it with no leak again ( started the tractor with the top cover off, I put a clear plastic line in the pressure opening and it pumped clear fluid instantly back in the reservoir. Now when I start the tractor even with the control lever all the way down (lowered) the 3 point arms will raise up all the way, right away. The entire top cover looks to be in very good shape, no rust or wear spots, everything seems tight and operable. The control lever works the control valve as it should - back and fort with no binding. The safety vale does not leak, I replaced the 7/16 steel check ball too ( the check ball seat looks very good). So, as it sits right now, the tractor starts up and the 3 point arms raise up all the way, right away even though the control lever is all the way down - it operated as it should when on the bench. I do have hydraulic fluid pouring out the opposite end of the safety and control valve side which is the baffle plate according to my IT manual. As soon as I can get the baffle plate from leaking, I might get it!, but, I don't know what the next step is. Does anyone know what the issue is? THANK YOU!

 

[Andy Wickiser]

Here is one possibility from an experience I had. I reworked the lift cover on my 800 and when reinstalled the lift would zoom all the way up like you are describing. I pulled the cover again and did the unloading valve which I had neglected before. When I reinstalled the cover the lift worked properly. Note I'm not saying this is your problem, just a possibility.

 

[Al in Il.]

Yes, that's quite possibly it. Maybe the unloading vale may be the reason why it dumps fluid out the baffle. I'll do some more research. Thanks for the reply Andy!

 

[JMOR]

(quoted from post at 19:39:55 07/05/21) Yes, that's quite possibly it. Maybe the unloading vale may be the reason why it dumps fluid out the baffle. I'll do some more research. Thanks for the reply Andy!

nloading valve is in fact your prime suspect!

 

[Al in Il.]

I completely removed the unloading valve, it looked like it was in perfect shape, it moved back and forth in the bushing like new. It is the earlier one with no O ring. I tried again with no luck, the fluid pours out the baffle end still with the lift arms raising even though the control lever is all the way down. Any other suggestions anyone?

 

[JMOR]

(quoted from post at 20:12:38 07/06/21) I completely removed the unloading valve, it looked like it was in perfect shape, it moved back and forth in the bushing like new. It is the earlier one with no O ring. I tried again with no luck, the fluid pours out the baffle end still with the lift arms raising even though the control lever is all the way down. Any other suggestions anyone?

luid exiting the baffle plate is normal for Lowering. That is where cylinder dumps.

I know that you said unloader (called bypass in these drawings) moves freely, but if control valve is mis-adjusted or valve or bushing has a problem, then unloader may alway sit in Lift position. One thought is that if you insert a wire into small hole and can feel the valve and especially if you can move it, you will be moving it away from Lift posn and into the Lowering position, therefore meaning that it was moved by your wire from the Lift position, possibly indicating that it is always in the Lift position. It should not have been in Lift if you last operation was a Lower command. Just brainstorming. One possible reason for unloader not moving is back pressure too low. Greater pressure is needed to move it to Neutral and Lower than to move it to Lift posn.

 

[Andy Wickiser]

Diagram below shows oil flow path required to lower the lift. Note that exhaust oil comes out of the baffle when lowered. Study the diagram and it should give you some ideas.

If you push down on the lift arms when they zoom up do they go down, or remain solid?

<IMG SRC=https://i.postimg.cc/Jhc1F8zV/Hyd-Oper-Princ0004.jpg>

 

[Al in Il.]

I was thinking MAYBE the back pressure valve was not working properly. Of course, these are no longer available from Ford. The pictures are a
big help to visually understand the inner workings. Thanks JMOR!

 

[JMOR]

(quoted from post at 21:58:52 07/06/21) I was thinking MAYBE the back pressure valve was not working properly. Of course, these are no longer available from Ford. The pictures are a
big help to visually understand the inner workings. Thanks JMOR!

f back pressure isn't working properly, I would suspect that it is not sealing well with the washer-gasket between valve and lift cyl casting, rather than the very simple back pressure valve mechanism which is nothing more than a spring and a washer without a hole (think coin). But of course anything is possible. Perhaps a piece of the old gasket that you replaced, stuck in valve, preventing it from closing?

This post was edited by JMOR on 07/06/2021 at 09:44 pm.

 

[JMOR]

(quoted from post at 00:37:21 07/07/21)

(quoted from post at 21:58:52 07/06/21) I was thinking MAYBE the back pressure valve was not working properly. Of course, these are no longer available from Ford. The pictures are a
big help to visually understand the inner workings. Thanks JMOR!

f back pressure isn't working properly, I would suspect that it is not sealing well with the washer-gasket between valve and lift cyl casting, rather than the very simple back pressure valve mechanism which is nothing more than a spring and a washer without a hole (think coin). But of course anything is possible. Perhaps a piece of the old gasket that you replaced, stuck in valve, preventing it from closing?

This post was edited by JMOR on 07/06/2021 at 09:44 pm.

few more over night thoughts.....if back pressure is too high (back pressure valve clogged, perhaps by debris or bent/crimped outlet tube, then back pressure would be too high. perhaps high enough to pass thru check valve &amp; cause ram cylinder to rise. If such were the case, I might expect the pump/engine to labor against high pressure at full lift &amp; continue in neutral &amp; lower. I think you would notice that. Also, might have weaker than maximum lift force available when control is in neutral and lower, but still lifting. Behavior still wrong with heavy load on arms? You earlier said that unloader had no o-ring.....does it have an iron ring &amp; or a grove for such?

 

[Al in Il.]

It is the earlier type with no provisions for an O ring.

 

[Al in Il.]

The lift arms stay up if you have the control lever in the up position when you shut it off. They do lower when shutting the tractor off if in the lowered position. The control lever is tight feeling if you put it in the upper/raised position when the tractor is running. I lower the control lever or shut off immediately.

 

[JMOR]

(quoted from post at 15:03:49 07/07/21) The lift arms stay up if you have the control lever in the up position when you shut it off. They do lower when shutting the tractor off if in the lowered position. The control lever is tight feeling if you put it in the upper/raised position when the tractor is running. I lower the control lever or shut off immediately.

ow about lifting &amp; holding heavy load? Any possibility of unloader bushing being re-installed 180 out (wide band vs narrow). Lower right corner in picture.

 

[Al in Il.]

No, It's in the bushing properly. I intend to check out the back pressure valve and see if anything is potentially malfunctioning. I'll probably
can't get to it till this weekend, seems like there's always something to do daily. Believe me, when I find the problem or get it fixed,
everyone will know! Thanks as always JMOR.

 

[Al in Il.]

I just posted a question (with pictures) about the back pressure valve. I can't get it to move at all from either end - can you manually get it
to do so? Seems stuck/frozen. If it maintains 40-45lbs of pressure all the time, I would think you could get the spring to move inside the body
manually somehow. Thanks.