Cat 422E hydraulics

[Kobus Oosthuizen]

Hi

I've got an issue with a CAT 422E where the hydraulic system is pressurized at startup and the machine can't start due to this. I've removed and cleaned the rear dcv, now doing the front dcv, but i can't find anything wrong. also checked pressure compensator valve on the pump.

when you actuate any of the functions whilst starting, it starts, otherwise no chance of it starting. Also no response from steering when trying to start. Can the steering valve be the culprit? This is the first time I've seen this.

 

[Mark250]

Hi as there are a few different models could you give your serial number please or at least the prefix.
the first thing I would do, would be to remove the load sense line going to the pump compensator. remove this line and cap it off. leave the connection at the compensator open (it will leak a little bit you can fabricate a drain line if you like to avoid mess
now try to start machine and see if this makes a difference .this will isolate pump from system
mark

 

[Kobus Oosthuizen]

Hi Mark

So i installed the dcv and started, problem was still there, took your advise and blanked off load sensing. Started again, same problem. I then removed the pump to see if it wasn't stuck on full stroke and it was. Also valve plate completely worn, about .75 of a mm groove in it. The ring on the stroke valve was also damaged. Even with rear cover removed the rotating group didn't slide back to neutral.

So I am going to get new spares an re-assemble.

Wil let you know what the outcome is

 

[Kobus Oosthuizen]

Hi

I'm stuck.. replaced the pump, still same problem, checked on load sensing lines and i am getting signal from front dcv to pump, when you remove the line it starts up.

this machine's model nr is 422EKHBE01950.

Immediate flow to the load sensing is that normal? And if so why only signal from front dcv?

Any help would be appreciated!

 

[Kobus Oosthuizen]

 

[Kobus Oosthuizen]

Sorry, just figured out how to post pictures, my pc is slow so i hit the buttons a few times

 

[Kobus Oosthuizen]

Took off dcv today, put it on mini test bench. When i give it flow oil comes out through cf port. What i did see when i started the machine is that the steering valve pressure line immediately pressurised. So i capped off cf port and now have oil shooting out steering load sensing port on dcv.

Ok, so now I capped off load sensing port for steering and oil is shooting out main load sensing port.

Is that suppose to happen?