Hi. I have hitachi ex270 that won’t curl bucket in. Loads the pump and engine. Also sometimes it will cause the right track to rotate and not stop until you pull the lever on opposite direction. All other functions work perfectly.
Welcome to HEF Clint . I assume this is a straight EX270 (no dash number). I believe the right side track spool is the first function to be supplied and the bucket spool is next in line in the main control valve 4 spool side. Both functions are supplied by the same pump. Pull the main hydraulic filter and check for any metallic debris.
4 spool side is supplied by the front pump , inlet is just before the right side propel. .
Hi. Filter is clean. Could it be a sticky spool or check valve.
Also if you feather the controls it doesn’t happen. Only full pull on the joystick causes the track to move.
Does the bucket curl in at all ? No issues dumping the bucket ?
It will very slowly. It loads the engine and hydraulics to do it. Also starts the right track. Also the track won’t stop rotating till you pull the lever in reverse. Everything else is great. Very strong machine
No issues dumping
So if I understand correctly, at full joystick bucket curl the bucket will slowly close and load the hydraulics and engine. At the same time , the right side track will start to rotate and continue to rotate until you put the track control lever in the opposite direction even though the bucket control is returned to neutral.
Yes. Also I noticed today boom lift caused the same problem. That spool is also next to the others
Sounds like the centring spring on the right propel spool is broken or weak and the spool is shifting when uncommanded. Remove the top spool cap housing ,pull the spool and check.
Ok. I’ll give it a try. Thanks
Spool and spring look fine. All spools on the right hand control valve float freely. Also this only starts when up to operating temp.
I assume what you are calling the “right hand control valve“ is the 4 spool control valve ? Very strange problem …. I would verify if there is a stray pilot signal shifting the right side travel spool. When the issue is active ,is the right side travel turning forward or reverse ? Maybe tee a guage into that particular pilot port of the right side travel spool. I doubt that it is a stray pilot issue but is the easiest thing to eliminate. Next I would pull all the external check valves on the 4 spool control valve and check for broken springs or poppets. If nothing found I think the next step would be to remove and split the main control in the two halves to check all the internal check valve springs and poppets.
Yes it’s the 4 spool control side. The track moves forward and I agree very strange. Been talking to some other guys about it and also never seen this. I’m also thinking an internal check valve but I will check the things you suggest. Thanks for your time.