Is it the transmission oil pump or main pump? Need help

ALFisher · Jul 28, 2013

I am fixing up a John Deere 2130 that the previous owner ran low on hydraulic fluid because of leaky seals on the lift arm. First, we fixed the brakes, one of which had frozen. Then, had to replace the reverser shaft. Now, it starts up and will work fine for a few minutes, then the power steering goes out then the tractor won't work properly.

Cleaned out all the lines to the main pump, checked the screens and replaced the filter. Fluid still not getting to main pump. Before I bite off another project on this thing is there a way to isolate the problem as to whether the main pump is the issue or whether the main pump might also need replacing? I am not sure I want to do both.

Also, based on the above how confident would I be in saying the trans pump is the issue?

Finally, would I have to replace the entire trans pump or just gears?

Thanks.

Zebrafive · Jul 28, 2013

The trans pump first pumps the oil thru the trans oil filter. If the relief valve for the filter is faulty it could be dumping oil back to sump. The trans pump also is what powers the reverser and (if you have it) independent PTO. An internal leak from either of these will not let the trans pump send enough oil to the main pump.
Tran pump is tested with a flow meter for 6gpm to main pump.
The main pump has filter called the stroke control valve filter. Might want to check or replace it.
A lot of things could be wrong with the main pump: stroke control valve, inlet valves, outlet valves, worn out pistons or bores.

Tx Jim · Jul 29, 2013

Trans pump pressure should be in the 155-165 psi range. Try operating hyd's with reverser in fwd & rev. Does tractor have a FEL?

ALFisher · Jul 29, 2013

No FEL. Will try those things.

As for the relief valve for the filter, we checked it, and it appears to be fine.

Zebrafive, where are you saying the leak could occur that it causing these symptoms?

Zebrafive · Jul 29, 2013

ALFisher said:
No FEL. Will try those things.

As for the relief valve for the filter, we checked it, and it appears to be fine.

Zebrafive, where are you saying the leak could occur that it causing these symptoms?

Leak could be from the small metal lines off the trans pump. I had one to my independent PTO clutch break. No hydraulics when it was engaged. Since all the trans pump flow was going direct to sump thru the broken line. I doubt a bad o-ring on one of these lines would bleed off all the flow. I am not sure what could break in the reverser, maybe the valve to cause an internal leak?.