What’s happening: When cold, the left track wont turn (fwd or rev)... IF I do doom down, left track will turn both directions if I am pushing down on ground. Swing doesnt want to swing when cold... after it warms up, if I run AUX (thumb) then swing kicks in and works fine. Until I stop swinging, then I need to run AUX again to swing back. Once warmed up left track operates fine (most of the time). If doing lots of things, swing works fine (I think its a pump firing thing). High speed tracking never works. Boost does seem to work either. Ideas on where to start looking? It does have a butcher job done to some of the wiring. Thinking that may be the issue with the SA, SB and SC solenoids, but curious what others think as I am new to excavators.
Rear pump on that machine supplies oil to the swing and left track. Sounds like it is not coming into stroke. The reason the left track moves when you move a hydraulic function is due to a valve called the flow combiner valve which takes oil from the front pump to supply both tracks. I am suspecting something with the rear pump control. I am suspicious of the wiring you mentioned. You may need someone with MPDr to connect to make sure all the pressure switches are doing what they are supposed to be doing. They can also check control pressure and system pressure operation while they are at it.
I got a Diag computer connected to it, it shows the rear pump 7117psi at idle... and the front is like less than 2073.7... If the wiring to the sensor (or the sensor itself) is bad, and the computer thinks its at 7000 psi, would it not TRY to stroke up, thinking it is already there based on the reading? I know I need to test with a real gauge, but I know it isn’t that high.
Unfortunately no, a pressure reading at the pump pressure sensor will not cause the pump to come into stroke. Lack of pressure from the flow sensing valve causes the pump to come into stroke. 7000 psi at that sensor at idle would be a sensor/wiring issue. Since you have a diagnostic computer to hook up can you read codes? If so what are they? Also need to know your serial number, last six digits will do.
Also let me know if you can see engine rpm in the computer.
Yes, I can see the engine RPM... at Max power I think it is around 1600 RPM, will check today. There are no current codes (two weeks ago - before I had the computer, I counted the blinking lights and had a open and closed codes for the rear pump). I checked the sensor connector and it was loose, I fixed that and now have no codes. S/N 0116## (not posting the entire number but that should be enough). Main valve was gone through, just before I got the hoe, but it had the same issues before the valve was gone through (they did not have a Diag computer).
So, I decided to check pressures with Diag computer today, w/o starting the machine. Both still showed pressure, so I unplugged them and went to 0, so I am leaning towards bad sensors. Does anyone know the part number of the pressure sensor(s) for an 892E? Also, if I unplug both sensors, if I start the machine, will pumps be at full stroke? Can I run it like that to see if my functions are fixed, or should I wait for sensors?
Please get me the actual rpm in "P" power max mode and there should be a reading titled engine target speed. What is the target speed when you are at "P"? You mentioned an rpm of 1600 in "P". "P" should be 2200 rpm. If target is higher than actual then the controller will destroke the pumps. Also the machine will not go to full stroke with the sensors unplugged. I attached a parts page and key #31 is your pump pressure sensors. You could try to cap off the lines one at a time from the "SB" and "SC" solenoids to the pumps to see if your machine works any better. SB can destroke both pumps and SC can destroke pump 2. Either way the pressure sensor issue needs to be resolved because that can affect pump stroke.
Set Engine Speed: 100% Actual Engine Speed: 1664 RPM (fluctuated some) Actual/Set engine speed difference -248 rpm (this number fluctuated some)... Is that what you wanted?
Let's get the engine rpm where it needs to be (see attached). Also get the pressure sensor issue fixed and we'll go from there. You can still try the "SB SC" solenoid stuff I mentioned in my last post.
Update: I replaced the sensors and adjusted engine RPMs. Not running, Pressures are FP 69.1 RP 241.9 RPM 16... I think these should all be 0’s, but machine is wet and snow covered, so thought it could be connection issues. Tested and same behavior as before adjusting engine RPM or changing sensors. I then cap’d SC and it appears that everything is functioning (waiting for it to warm up to test all hyd functions). Front pump stays at around 450 psi until I try to run something (then it rises), rear pump, changes with engine RPM from 1071 (I setting) to 1520 (P Setting) with no load and SC cap’d. —— Warmed Up... With it Cap’d it tracks fine, swings good and seems WAY better then before. I reread my initial post and noticed a typo... Boost didnt seem to function either. — Boost still does not appear to work and neither does high speed (computer does show the signal being sent). So, how would you proceed? Start putting manual gauge off of the SA, SB and SC..., look at the feeding line to that valve bank or go electrical? (Not sure how to troubleshoot PWM solenoids, I know how on regular solenoids). I looked at the butchered wiring, and it appears to all be for an aftermarket valve added for the quick attach. Those wires don’t seem to go to the SA-SC solenoids.
Hook SC back up. Try it unplugged electrically to see if it operates like it does capped. Try SB unplugged (SA does not affect pump flow). Monitor switches in diagnostics to see if it indicates precision mode when it shouldn't be on. Do the propel pressure switches work? Go off when not travelling? Or are they stuck on? I'm still concerned with the wiring. Any pressure switches that are activated that shouldn't be can affect pump flow and also affect things like boost and travel speed. Also time to check flow sense pressure (see attached). Make sure everything is hooked up back to normal for the flow sense pressure test. I am also concerned about your post #6 comment about the valve having been gone through, lots of check valves in that valve and Deere/Hitachi has had some issues with them. Sorry for all the questions. Troubleshooting excavators are tough enough when one is at the machine, even tougher from the seat of my pants across the country.
Mg2361, I understand the difficulty of troubleshooting things remotely BUT I really appreciate your help and guidance. I am a decent mechanic on my farm equipment, but the excavator is a whole new animal to me. I’ll try to get those things tested today.
mg2361, So I didnt have the right connections for gauges to do the Flow sense pressure test (getting those). But here is the other info: SC unplugged - does not work, SB unplugged does not work. Via Diag computer, pressing propel pedals, pressures go up and down for both left and right (31.1 PSI stopped, 660 PSI pressing pedal). Precision Mode status on the computer, changes when the mode is changed. Propel/Dig pressure switch gets signal according to computer. Believe we have verified that SB and SC are getting electric signal. In all power modes, pump displacement solenoid control is 0, if either propel is pressed it goes to 712 psi. Pump flow rate control pressure in all power modes: GPI 0, GPII 0, Grading 327 PSI, Precision 398 psi). The Grading Mode Shuttle Valve has been replaced, but appears to be plumbed correctly and the ball does move in it. Quick question, and it may be in the docs you sent, but what should the pressure be at SC? Curious if its pressure is not enough to overcome the pressure from the flow sense valve to move the shuttle (or the flow sense valve is not bleeding down to a low enough pressure for SC to override it in the shuttle)? (Because SA, SB and SC are 3 things that do not work, but that wouldn’t explain why rotate doesnt work).. So, I need to do the test you recommended, to see if its correct.
I attached items for the solenoids. I'll wait to see what your pressure readings are for the Flow Sense pressure.
This might help also.
We tested the pressures (flow control and SC), and everything seems to be close (our gauges weren’t quite a good enough scale). But, everything seemed to change as the papers suggested. We can still cap the line, and force the pump to work and pressure is at 0. If all our other pressures are in range (we believe they are), we were wondering about an issue with the pump regulator. Is that the next step?
If your flow sense pressures are doing what they are supposed to be doing then yes you may have a regulator issue. If capping off SC gives you normal operation then you may still have a control issue. Unfortunately I am tapped out at this point. Without being there to see, hear, feel the situation or to run tests myself I have no further advice to offer. I think your best bet at this time would be to contact your Deere dealer and have them look at it. Sorry!
Mg2361 - THANKS for your help. Will let you know what we figure out.
Mg2361 - so, your docs seem to have a lot better information than mine. Do you have specifications for setting the 3 adjustments for the pump regulators? Our docs show the minimum and maximum displacement settings, but do not describe how to properly adjust them. We are thinking they are slightly out of range.
PM me your email and I'll send you everything I have for regulator adjustments in one shot. The most important adjustment you will make out of the procedures will be the engine pulldown adjustments.
I think I sent a pm...
sounds like the swash plate is sticking(common problem) You can replace the swash plate and the rear cover on the affected pump cheaper then the whole pump. Remove the pump cover bolts and remove the swash plate.It may look like a gravel road .If you are really hard up for cash you can try and polish both surfaces but you can have success by replacing both.
I assume you need to remove the pump from the excavator to do this?
Is this an inspection cover, at the very bottom of the picture?
I assume you mean the almost square plate on the top of the end cap? That would be the end cap for the swash plate control piston.
Joeblow, are you saying pull apart and look at ‘B’ and ‘D’ (see pic) and if not smooth, replace those pieces?
Joeblow, well it doesnt look like gravel... but it shows wear and is a little rough. Also, the measurement for the pin and swash plate are slightly over the max limit of use by .004 inches. Note: there is wear on the left side as well (when looking at the cover picture).
Mg2361 and Joeblow... (and anyone else who may care). Ordered a new valve, cap and misc seals and o-rings. Got the pump pulled, rebuilt and reinstalled. We found when that the valve and cap while rough they would stick some unless the hydraulics bounced or surged a little. Also, we found that the piston that moved the valve had a slight sticky spot as well. So, once back together it mostly seems to work as it should. Still have a few things to work on, but its like a completely different machine. THANKS!!!
Awesome! Thanks for the update.