EX270-LC Need help with hydraulics

[BlackbeardMX]

I've posted a couple times with some questions about this machine. Now I need some help with the pump controls. The wiring to the solenoid valves was damaged in a small fire. I have repaired it, but I think the coils themselves are also bad. The manual describes what three of the solenoids do, but the one that is separate from those three is never described. It is shown in a couple illustrations, but never mentioned in the text. It also isnt shown in the wiring diagram. it has three hoses connected to it. One is pilot, one dumps to the tank, the other connects to the pumps. Anybody know what this valve does?

The hydraulics on this machine are very unpredictable. Not smooth at all. For instance, try to make one track operate. Doesnt do much. Move a boom function and it starts to work. You cant do anything delicate with it. Another example, try to raise the main boom. Pull back on the lever a little and the engine loads but nothing happens. Pull a little further, and it goes up very abruptly. I dont think this can all be blamed on the coils not working unless this mystery coil does something important. I think an orifice is clogged somewhere. There were some hoses burnt off in the fire, so I'm thinking maybe some debris clogged something or stuck a valve. I downloaded the manual, but its not really much help. Doesnt cover alot.

 

[tool_king]

Hi BlackbeardMX
Can an you email a picture of the solenoids where they are.My email address is tool_king@hotmail.com
THANKS
ED

 

[BlackbeardMX]

I dont have a pic right now, but if you open the door on the left rear of the machine, they are in there. Behind the hydro tank.

 

[bwmwaima]

Sounds like the pilot pressure regulator, should contain plunger, spring, shims, under the screw off cover.

 

[shopguy]

Does it do the loading before it moves thing on all the functions or just the cylinders?

 

[BlackbeardMX]

It seems to do it on all fuctions. Late last night I found a bunch of dirt in the pump regulators. Gonna take em off and go through and clean em out real good and see what happens. the dirt probably got in there when the hoses burned off.

 

[BlackbeardMX]

Cleaned the regulators. Didnt help at all.

 

[shopguy]

I wish i could be moore help but i have trying to get that out of one myself,please let me know when you fix it what it was.
Thanks

 

[BlackbeardMX]

Ok, I will. Pulled the solenoid valve (which houses the pilot regulator) and cleaned it this morning. Didnt find anything. Putting all new solenoids in it. Will post back when I get it back together. Talked to a guy that used to run this machine some for the previous owner. Said it has always had some problems. Said the engine would bog for no apparent reason sometimes. Said they replaced pumps pretty often on it over the years.

 

[shopguy]

Sounds like mine ,I will say this dont throw parts at it that is what everyone does (me too). Test dont Guess

 

[stondad]

Have a look back through old posts guys. I'm sure that there was someone a while back who sounded knowledgable about the computers. Cant remember what brand and I am assuming that yours are Hitachi. Your little fire and wire replacement makes me think in this direction particularly as you are not having much luck yet on the oily side.

Have been watching you with interest since you first posted this problem but it is years since I touched an excavator so I couldn't add anything to help until now.

What dash# are your machines and year of manufacture?

 

[BlackbeardMX]

Mine is a dash 1. Somewhere around 1990.

 

[stondad]

Aha! So you would have hydraulic pilot lines to your joysticks instead of electronic proportional control? If so, forget what I said about a computer. Does your manual have a hydraulic circuit diagram?

 

[danc]

after the hose fire are you sure the pilot filter is flowing freely.

tee into the line going to filter with gauge and check pressure also.

The solenoids are for running the preset dig modes controlling engine rpm and pump displacement.

the manual isn't too clear on exactly how it does it.is it simple on off or a high speed switching solenoid?. My own machine (ex120#1) had issues before and all the solenoid wiring is disconnected, so I can't test it electrically.