I'm used to things to problems with the excavator getting worse. But today a problem actually largely disappeared. Prior to today, the Hitachi EX270 LC boom and stick would not hold in the air without falling. The boom would drop steadily, even without a load in the bucket. With the clean up bucket full of wet muck (two to three cubic yards of material) at full extension, it would fall relatively fast. That meant that any loading operation required rapid action (as in very fast) to dump the bucket. For the past few weeks, I've been using the excavator to load into a large loader bucket and using the loader to haul the muck away. The ground conditions are too wet for the loader to have much traction, so loading the loader bucket with the excavator is the easiest way to fill the loader bucket efficiently. Needless to say, the excavator and loader bucket have had a few close encounters. Today, for no apparent reason, the problem largely disappeared. Without a load in the bucket, the boom and stick will now remain aloft for an extended time without falling. And loading became much easier as the bucket did not rapidly descend when heavily loaded. This allows for a lot more finesse and control. This is so easy compared to before! Explanation? A piece of O ring or other debris had been jamming a valve somewhere and finally dislodged? Any other ideas??
Has the machine ever had a catastrophic ram or pump failure resulting in metal going through the system? Our 330Bl had metal go through the system and now it has its moments. Shane
If that sort of boom drift was caused by contamination from a pump failure I would not expect it to "repair" itself. Where your hyd oil temps high when the boom was drifting? I would consider maybe a sticky valve spool? Just an idea.... I would pull the filter and take a peek, install a clean out filter and do some cycle time and boom drift tests.
The boom drift was there since I bought the excavator last year. I just accepted it as part of owning a well used machine. From my experience with various used machines, many of them have some drift. The former owner told me that the machine had new (not rebuilt) pumps installed a few years ago. I can't say if that followed a catastrophic failure. The pumps seem very good - quiet and strong. When I recently replaced the gear transmission seal and drained the hydraulic oil, I removed both filters in the tank and cleaned the hydraulic oil tank. Both filters and the bottom of the hydraulic tank were clean with virtually no filings or other crap. The biggest thing I found was half of a small (1/2 diameter or so) O ring. 3thirteen - Any idea which valve spool might be involved in this, in case the problem recurs?
Sounds like a sticking spool in the control valve. Do you have a service manual? I'm not sure which spool it is off the top of my head in relation to when it's in the machine, but Wajax should be able to tell you.
swampdog After some more thought I think there is also a chance that your line relief (boom circuit) could have been sticking. Did it sound like it was going over relief when the boom would drift? A sticky valve spool could still be possible this is another avenue you could investigate. Regarding the location of the valve spool; it would be in the main control valve and on the boom circuit. I am not exactly sure where physically on your machine that would be. I hope that helps you out, my experience is almost strictly Cat with a little Case and Komatsu. With a little more info I could ask around and get a more solid idea. Good luck; let us know how things work out.
Does your machine have a check valve on boom cylinder ? same thing happen when the check valves are weak
Thanks everyone for the ideas. That will give me a few places to look first if I decide to start taking things apart. It still has a little drift, especially with the large cleanup bucket fully loaded with heavy muck and the boom and stick extended. Maybe at that point an overload relief valve cuts in??? But, overall, it does seem better than before.
Could i get some help here, new member. Also relatively new to operating, jus bought a 06 Case Cx210 with about 4000 hours, has safety valves on boom cylinder. Problem is the boom keeps falling slowly whether or not its loaded. I also am hearing what seems to be air leaking close to the main hydraulic pump. Finally i'm not sure if its normal but swinging from left to right you hear a slight grinding noise when you slow to turn the opposite way. Any advice is greatly appreciated.
Grease the slew ring and bearing, the boom drop must be a seal failure if the machine has check valves fitted O! and a hearty welcome to hef,did you bring any photos Stock
Thanks Thanks for the speedy reply, but you would have to help me by being descriptive now, i'm no stranger to maintainence but mostly on trucks. I'm sure if i can locate them i can get it done.
Pics I'll be back with the pics later.
Case Cx210 This is my toy.
hope this is as good as a 1000 words items 15 ,16,17,18,19 may be the cause of your distress. Stock
If i don't see any oil on the outside what does that mean?
This happens internally with a drop in the ram being the only evidence of a fault. Stock
Slew ring You were saying i need to grease the slew rings. i see there are three nipples under the upperstructure a little way for each other, are these my target. Because i started greasing them but two don't seem to be taking much ( grease is already coming out ) and one seems to be blocked. Any advice? thanks
i'd say your grease nipples are buggered. Replace the nipples and try again. I'm not sure how familiar you are with grease guns but most **** grease everywhere if you aren't holding the grease gun on square.
New nipples, same problem for one of them. Strange thing is, i removed all three and one has smaller thread than the other two. Now they are in somewhat of a triangle and this odd one would be at the top of the triangle. It just so happens that this smaller nipple is the one not taking grease. Is this significant or not?