2005 John Deere 120c slow final drive and dipper

[Doug802]

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.

 

[mg2361]

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.

 

[Doug802]

The excavator cab display will give me the pressures?

 

[mg2361]

The excavator cab display will give me the pressures?

Yep.

 

[Doug802]

Figured out the pressure from the screen. .6 on bucket curl, 20-30 when moving stick or arm

 

[mg2361]

.6 on bucket curl

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.

 

[Doug802]

Stalling the bucket didn’t raise the pressure on the screen

 

[mg2361]

Control pressure? Position #4 I mentioned in post 6.

 

[alaskaforby4]

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.

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!

 

[mg2361]

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.

 

[Doug802]

4.3 when using boom and stick to drag bucket on the ground towards me and while curling in bucket

 

[Doug802]

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

 

[mg2361]

If stalling bucket curl is showing 4.3 for the control pressure then I am still leaning towards the isolation check valve.

 

[Doug802]

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

 

[mg2361]

ust to be 100% sure, by stalling the bucket you mean curl it in all the way and hold it there?

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.

 

[Doug802]

If I hold bucket curl in I get 4.3

 

[mg2361]

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.

 

[Doug802]

So is my next step testing the pressure at the pump?

 

[mg2361]

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?

 

[Doug802]

23.6 idling and while stalling arm