2005 Deere 120c, one track is super slow and the curl on the bucket is super slow as well unless you move the stick or boom at the same time then the bucket will curl fast like it should, track doesn’t speed up. No grinding or loud noises from the pump or anything. Possibly thinking a pump issue but not sure where to start.
Sounds like an isolation check valve issue. First you need to check pump output pressure for pump 1. Press and hold the set button and start the machine. When bulb check is done release the set button. Then press select until the display shows a number 2 on the left side of the display. The number on the right side of the display is the pressure. Stall the bucket and report what the display says.
The excavator cab display will give me the pressures?
Yep.
Figured out the pressure from the screen. .6 on bucket curl, 20-30 when moving stick or arm
Is that the stall pressure (spec is 33.8 - 36.3)? That one should have had a #2 on the left side with the pressure on the right side. Now go to #4 on the left side, stall the bucket curl and read the pressure on the right side and report. #4 is the control pressure to pump #1. Should be in the 3 - 4 range when stalled.
Stalling the bucket didn’t raise the pressure on the screen
Control pressure? Position #4 I mentioned in post 6.
this is amazing info! where can I find more info on what number corresponds to the parameters? we have a 160c and a 120c Thanks!
If you are doing all your own troubleshooting/repairs I would recommend the Operation and Test manuals TM1934 for the 120C and TM1932 for the 160C. I PM'd you.
4.3 when using boom and stick to drag bucket on the ground towards me and while curling in bucket
For a very short period, a few seconds the curl operates like it should and it tracks fast on both side then it stops and the right track is super slow again and the bucket curl is as well. Can’t get (2) to get up to 30 like it should be
If stalling bucket curl is showing 4.3 for the control pressure then I am still leaning towards the isolation check valve.
Just to be 100% sure, by stalling the bucket you mean curl it in all the way and hold it there? Doing just that doesn’t make the pressure go up, it stays at .6 on bucket curl but when moving the stick it will go up in the 20s
Yes, but looking at control pressure item #4 in the monitor, not system pressure item #2. Also check #4 while curling with the lever at full stroke. Only the bucket function. No other functions.
If I hold bucket curl in I get 4.3
Then you have plenty of pressure telling the pump to come into stroke. So either the pump is not reaching full stroke or it is leaking past the 5 spool side isolation check valve.
So is my next step testing the pressure at the pump?
No. The control pressure and the delivery pressure sensors are both mounted on the pumps so you are measuring at the pumps. At this point the only way to isolate the pump from the rest of the circuit would be to perform a pump flow test. Since that is not tooling the average equipment guy owns we have to do more of a hunt and peck approach. The fact that the bucket circuit picks up speed when you stroke another function tells me the pump is capable of putting out. Moving the boom or arm seats the isolation check valve since that pressure is more than likely higher than the bucket circuit allowing all of the pump 1 flow to get to the 4 spool side, instead of leaking to the 5 spool side, speeding up the bucket/travel circuits. Since you have plenty of control pressure and the pump 1 delivery pressure gets to at least 20 mPa tells me the pump is coming into stroke. The oil coming out of the pump is possibly leaking past the isolation check valve causing the slowness issue. It is a lot easier to check that and if an issue is found it is a lot cheaper than doing pump repairs. I never asked, check item #3 on the monitor and stall the arm out. What do you have?
23.6 idling and while stalling arm
Full throttle?
Yes, full throttle it stays the same
It is supposed to be 33.8-36.3. Did you measure using #3 on the monitor? If not monitor #3 when you stall arm out.
That is monitor #3. Idling it’s 23.6 using no functions and full throttle using functions and stalling it out it stays 23.6 doesn’t move a digit
I don't have a spec but that should read something like 4-6 at idle and levers in neutral. What does it read with the engine off and the key on? Check #2 also, both key on engine off and at idle levers in neutral.
#2 is .6 at idle. 0 with key off #3 is 23.3 at idle 23.3 with key off
If you swap the wires between the 2 pump pressure sensors does #3 still say 23.3? If not then you need to replace the pump 2 pressure sensor. If it still reads 23.3 then there is most likely a wiring issue.
When I swapped the wires #3 shows 0.0
That's key on correct? If so, let's start with replacing pump 2 pressure sensor.
Key is on. Gonna order that part
Replaced pump 2 pressure sensor. #3 reads 0 when engine off, key on. 1.1 at idle. 34.6 when revved up stalling arm. Dipper and track still slow
When stalling bucket and watching #2 is it still low (below 33.8)? if it is I go back to my first post and say check the 5 spool side isolation check valve.
How do I check the 5 spool isolation check valve? I bought the operation and test manual. #2 stays at 0.6 when curl bucket in and holding. 35.1 when I hold boom back all the way
The operation and test manual section 9025-05 (Hyd Theory of Operation) look for control valve operation. The picture that shows the left rear bottom of the control valve item #59. That cover has to be removed to inspect the isolation check valve. Make sure everything is on the ground, relieve the pressure from the hydraulic tank and put a vacuum on it (or drain it) before removing the cover. Also there will be more than just the check valve under that cover, so remove slowly and watch that nothing drops. The isolation check valve should be the one closest to the end of the control valve.
I found it in the manual but can’t tell from the picture where item 59 is on the machine.
Can you see it from that picture?
No it is not in the picture. It is not easy to get to either. Since you have control pressure (post #16 above) to your pump and no output to either the right track or the bucket circuit then you are down to 2 things. That isolation check valve dumping pump 1 flow to the pump 2 side or a pump regulator that is stuck/sticking not allowing pump 1 to come into stroke.
You got this Doug! I have a 160c and it has developed a slight leak right where MG2361 has the arrow. Its a large block bolted to the side of that even larger block. Its leaking on both sides. I imagine a o-ring or gasket in there has partially failed. It looks like quite the project getting it torn down that far. Let us know how it goes, tell me its easier than it looks
Not to highjack but i have similar issue .I got a 160c had lots of issues and previous mechanics two sets of pumps.... I got all the electrical straightened out. Clean tank filters and strainer no metal. Right track and bucket seem normal. Anything on 5 spool / pump 2 pulls engine down. Left track and stick is to fast. Both build relief pressure in spec. I flowed pumps no load at idle pump one 14 gpm pump 2 18 gpm. Will flow at 2000 rpm and then 2000 rpm at 2000 psi in am. Both have same low signal pressure 4.0 when working functions. What should I look for with pump 2 flowing more or not destroking thanks hef
Measure how much the screw on the top side of the regulators stick out on both pumps (spec 18 - 18.5 mm). Otherwise lets just wait and see what the 2000 rpm/2000 psi flow test reveals. Also, if you would please, when you are ready to post the results start another thread .
UPDATE. Handed the machine off to a mechanic and he pulled the hydraulic filters and found metal in them which means the main pump is bad. Bought a reman for it and hope we aren’t fighting with metal sticking in valves and such for a while