Yanmar 240 Loader Hydraulic issue

[Soundguy]

Ok, no problem, you have no understanding of Hyds..

In an open circuit Hyds system, the pump continually pumps, and if a valve is not used to direct oil at a cyl, its dumped thru the valve back to the tank. Only pressure there will be interior hose surface ate resistance to flow based on hose Id and gpm of pump. Much lil a garden hose.. On, with nothing restricting the open end it just pours out.. Put your thumb on the end, restrict it, pressure goes up, flow goes down, and it sprays.

If your system is open circuit there is no appreciable pressure till a valve sends fluid power somewhere other than sump. You can get low double digit pressure from min resistance, and if it uses a backpredsure valve.. Lil 40 psi, etc.. Not much..

There are other Hyds systems, closed circuit, etc.

 

[Soundguy]

Well, look at it this way... There are those of us that can, and there are those of that can't.. We're to try to help those that can't

Sure.. But should it take high double digits of posts saying to observe return flow, or to see if the loader comes down with hose off?

Really..

 

[kenmac]

Sure.. But should it take high double digits of posts saying to observe return flow, or to see if the loader comes down with hose off?

Really..

I concur

 

[clemsonfor]

yes you are correct a hose pressured up to 2500psi will spurt out unde quite the pressure!

 

[jb92563]

Last weekend I opened up the hydraulic lines to the Loader raise cylinders at the valve, then at the cylinder and checked that hydraulic fluid was making it to all those points in both the raise and lower circuits, which it was.

Oddly the loader bucket would not lower with both lines open so there must be something going on inside the cylinders themselves. Somehow they are jammed up internally?

I did remove one lift cylinder and with the hydraulics hooked up I could not get it to move in either direction.

I guess I'll have to take the thing apart. I'll also try the other cylinder while disconnected from the frame to see if the cylinder will move at all as its does not seem likely that they would both jam up at the same time. By doing this I am hoping to confirm that the Hydraulic pump is still functional by getting one cylinder to move.

Still seems odd though that even though the lift cylinders are not working, the bucket curl should at least work. Thats why I suspect that there might be something wrong with the Hydraulic pump.

I also made sure that hydraulic fluid would flow at all the couplings on the lift/lower circuits, which it does. I suppose I should try the bucket curl circuits as well.

I can't imagine how a cylinder could bind while nearly fully retracted but opening it up may reveal some major failure.

Now that I think about it, I did notice on a few occasions that the bucket lowering was not quite smooth, a little jerky and perhaps that was a sign that something was starting to bind inside a cylinder.

I get the feeling that I will be ordering 2 new cylinders soon.

 

[Soundguy]

as has been said.. make sur eit is not a mechanical hangup in the laoder frame too.

with the cyls disconected from lines, try moving them.

put a pressure gauge in one of the valve ports and pressurize that circuit.. see what the pump can make and then relieve at.

use a 3000 psi gauge.. most ag pressures are in the 2500 psi range..

 

[Soundguy]

as has been said.. make sur eit is not a mechanical hangup in the laoder frame too.

with the cyls disconected from lines, try moving them.

put a pressure gauge in one of the valve ports and pressurize that circuit.. see what the pump can make and then relieve at.

use a 3000 psi gauge.. most ag pressures are in the 2500 psi range..

 

[clemsonfor]

i was thinking too, time for a pressure gauge. I would block up the loader and take the cyliners off and see if they will retract with they out of the loader mounts and then start digging from there again. a pressure gauge if you can find/borrow one will tell you if the pump is working.

 

[jb92563]

Mystery solved!

I had some time to work on the tractor and figured after trying all the other suggestions, that the only thing I had not taken apart was the auxiliary Hydraulic pump for the loader.

2 Bolts off the pump and it slid right out, which is not what I was expecting as I figured there was something holding the coupling onto the pump shaft.

Nope, the set screw and shaft key were both gone.

No key, no set screw means the shaft of the hydraulic pump was not turning = No front end loader hydraulics.

Since I started this thread a Tractor Supply store opened across from the Home Depot so shaft keys were readily available, not in the correct size so I had to do some creative key reshaping with the dremel.

At first test the bucket curl is working again but I think I need a few more minutes to get the bucket lift working by getting all the bubbles out of the lines.
I read that it bleeds itself so the bubbles work their way into the reservoir after operating the Hydraulics for a few minutes.
My battery died so I'm waiting to for the charger and thought I'd update this subject. I hate unsolved mysteries.

Thanks for all the help offered. I learned a lot about hydraulics in the process and once again that its always the $1 part that typically breaks and should always be suspected first.

Ray

 

[Soundguy]

Thanks for posting back.

Yup, its always a pita when a 1$ fuse stops a $$$$$ machine.