Hitachi zx 350 with lift problems

[Drydenjason]

We just bought a zx 350 and it has about 5200 hrs. When it gets warmed up the lift control gets very jumpy, like the valve is sticking or something. Once the valve opens it's smooth but when you first pull back on the lever slowly it won't lift and you keep slowly pulling back on the lever then all of the sudden the bucket will jump up about six inches. It does this every time you make a cycle or raise the boom then lower it. Any ideas would be greatly appreciated.
Thanks

 

[mikebramel]

Not sure what test equipment you have but you either have an actuation problem form the pilot pressure, pump not coming online, or mechanical with the valve spool to bore. If you get an inline gauge tee into the pilot lines and compare two circuits it will be easy to tell if you have a problem there, if not you can feel the clearance to bore by hand after dissasembly. It would be a good idea to check the cylinder as it may have or did fail

 

[Drydenjason]

We don't have any testing equipment, I just wanted to get some kind of idea where to start looking. It seems like a pump starts to engage when it jumps up because you can hear more noise in the cab. Any advise on someone that can come out and run some tests on it in the Minneapolis area?
Thanks so much for your info.

 

[mikebramel]

http://catalog.hydracheck.com/viewi...seal-female-x-male-straight-with-gauge-ports?
http://catalog.hydracheck.com/viewitems/pressure-test-products/pressure-and-vacuum-gauges?

 

[KenAl]

I had the same problem on a ZX350LC-3. Had to adjust the "Pilot Characteristics" on the main regulator of one pump. The pump was coming "online" before the spool was moved giving the jerky symptom. Monitored the main pressure for the pumps on the monitor and lifted one track up in the air. One side would build up a lot of main pressure before it would move. Not good. The other side would start to move at a lower pressure. Adjusted the pump to make the one track start to operate at the lower pressure the same as the other. Tried the boom and now it was OK. I do not like, or adjust pumps very often as if no one has played with the settings it is usually something else. But in this case everything I monitored suggested the pump was stroking before the spool was moving. I was not able to keep tabs on this machine to see if things changed as I suspect there was more going on. This regulator/pump combination has been used in many models and it was the first time I had to do that. Suggest you get someone that knows what they are doing to do this.

 

[zxy320d]

check here.

 

[Lee (MN)]

Call RDO in Burnsville and tell them you want Allen to come out and check it out, Very sharp guy!, knows these machines well.

Lee

 

[Drydenjason]

Thanks, I think I may have to give a call.