Hydraulic issue on JCB 214

[mufwapo]

I've got a bit of a problem I can't quite figure out if anyone would like to take a stab at helping me fix I'd sure appreciate it. I have a 1997 JCB 214 with about 4000 hours on it. It worked great for years and then a few days ago while using it all of the hydraulics froze up. I found that if I throttled down to idle they worked again but they were slow(which they should be at idle) but when I throttled back up they would move a little bit and then freeze again. When the machine is cold it will do this without fail. If I let it run for 30 minutes or so everything works perfect for anywhere from 1 to 30 minutes and then it freezes again and I have to throttle down to idle to get it going again.

So far I checked that the fluid is good, filters are fine, no hoses collapsing between tank and pump and nothing leaking out of the ordinary.

Any thoughts on this?

[martyn williams]

Hydraulic pump ? perhaps put a guage inline and take some pressure readings on the output side. I would look to the pump first Chech pump drive is OK.
Hope this helps
Martyn

[mufwapo]

The pump drive is fine and I considered the pump already but it's not acting like I'm losing hydraulic pressure, it's like the flow of fluid is stopped very abruptly. If I increase the throttle slowly while I'm raising the front bucket it will gradually speed up and then stop so suddenly it tries to lift the front of the machine up. To me if feels like something is blocking the return of fluid or somewhere in the lines a valve is closing when it shouldn't be. I'm in the process of getting some test fittings so I can see what the pressures are in the system.

[martyn williams]

Its pointing to a check valve or pressure relief valve that is blocking or dumping.
Martyn

[mufwapo]

Its pointing to a check valve or pressure relief valve that is blocking or dumping.
Martyn

That's exactly what it feels like to me! Nothing is leaking anywhere but I'm not sure if any relief valves are plumbed back to the tank. I'm also not sure how to go about locating where the issue is.

[Mark.Rive]

You checked here ? JCB 214 3CX 1400B workshop manual

Cheers Mark

[mufwapo]

You checked here ? JCB 214 3CX 1400B workshop manual

Cheers Mark

I did but that appears to be newer than my machine. I don't have the serial number off hand but it's a 1997 with a front mounted pump and hydraulic controls, not electric. Thanks though!

[martyn williams]

Have a look at the valve block. Look for test points that a guage can be fitted. Is the oil flow being diverted to an aux. line ?
Check the system in sections,tank to pump, pump output to the services,then services from the valve block.
Had a similar fault on a machine years ago.Everything seemed in order but lost power on hydraulics after a while.I removed the suction side pipe. Inside of the pipe was degrading causing the inner layer to drop down cutting oil flow by restricting the bore of the pipe.On closer inspection the wrong pipe had been fitted as it was not reinforced enough to overcome the suction so eventually the internal section of the pipe collapsed but leaving the outer layer seemingly intact.
Martyn