M4900 Hydraulic Problems. Power steering, PTO are OK. Everything else weak

[wheelinag]

Well now I'm even more confused. I took the main relief valve out again, disassembled it, put it back together and in the tractor. Started it back up, still have the gauge hooked to the "in" port hose. Had it running for a couple of minutes while messing with the adjustment of the relief valve, I heard a noise and the gauge shot up to 1300 psi. I was at about 1800rpms. 3 point is now not working.

I shut it off and then started it back up again and now I have under 700psi again.

 

[TheOldHokie]

About 99.9% sure. Here is valve I took out and inspected. And yes, I hooked the gauge directly to the hose.

Not sure where to go from here. Is there another relief valve in the 3pt system? I'm hesitant to mess with the pump because I think I'll just end up with the same result.
d youd youv

Pretty sure you got the right relief valve. How did you go about setting the adjustment screw?

Ideally the next place to go would be a pump discharge pressure test but thats not an easy test to plumb up on that tractor.



Dan

 

[TheOldHokie]

Well now I'm even more confused. I took the main relief valve out again, disassembled it, put it back together and in the tractor. Started it back up, still have the gauge hooked to the "in" port hose. Had it running for a couple of minutes while messing with the adjustment of the relief valve, I heard a noise and the gauge shot up to 1300 psi. I was at about 1800rpms. 3 point is now not working.

I shut it off and then started it back up again and now I have under 700psi again.

Thats encouraging and sounds very much like the relief valve is misbehaving. Three point wont work because your gauge has power beyond blocked.

Try that again. Watch the gauge as you turn the adjuster in. Pressure should increase as the screw is advanced. System setting is 2700 PSI.

Dan

 

[wheelinag]

Thats encouraging and sounds very much like the relief valve is misbehaving. Three point wont work because your gauge has power beyond blocked.

Try that again. Watch the gauge as you turn the adjuster in. Pressure should increase as the screw is advanced. System setting is 2700 PSI.

Dan

The sound came from the front. I'm assuming the pump area since the pressure line isn't hooked to the loader.

I can tell when the relief valve is doing something as when I back it all the way out, like to a 100psi, I can hear a change in the engine. When I screw it in a little, which only gets me back up to 500-700 psi, I can hear the engine change again.

It definitely has some volume going through it. Just for curiosity, I took the gauge of the line and put it into a bucket open flow. Probably shot out half a gallon pretty quick.

Are these pumps 4 bolt flanges or something proprietary?

 

[TheOldHokie]

The sound came from the front. I'm assuming the pump area since the pressure line isn't hooked to the loader.

I can tell when the relief valve is doing something as when I back it all the way out, like to a 100psi, I can hear a change in the engine. When I screw it in a little, which only gets me back up to 500-700 psi, I can hear the engine change again.

It definitely has some volume going through it. Just for curiosity, I took the gauge of the line and put it into a bucket open flow. Probably shot out half a gallon pretty quick.

Are these pumps 4 bolt flanges or something proprietary?

In the parts diagram pump looks like a 4 bolt flange but whether its standard or not ?????

Damn relief valve is $500 !!!! Before poppimg for that I would do a pump discharge test. Do you know how thats done?

Dan
Dan

 

[wheelinag]

In the parts diagram pump looks like a 4 bolt flange but whether its standard or not ?????

Damn relief valve is $500 !!!! Before poppimg for that I would do a pump discharge test. Do you know how thats done?

Dan

I do not know how to do the discharge test. I'll take a look in the WSM.

 

[TheOldHokie]

The WSM procedure involves a ($$$$) flow meter.

You can accomplish the pressure portion using this test rig:

1. Remove the delivery pipe from the pump and connect an adapter plate.
2. Connect the adapter to a tee with gauge in the middle.leg
3. Put a 3000 PSI needle valve on the third leg of the tee.
4. Run a hose from the needle valve to the hydrauluc filler

Fully open the needle valve and start the tractor. Then slowly close the needle valve while watching the gauge. Pressure will begin to climb as you clise the valvr. Stop closing the valve when you get to 2700 PSI.

Dan

 

[wheelinag]

The WSM procedure involves a ($$$$) flow meter.

You can accomplish the pressure portion using this test rig:

1. Remove the delivery pipe from the pump and connect an adapter plate.
2. Connect the adapter to a tee with gauge in the middle.leg
3. Put a 3000 PSI needle valve on the third leg of the tee.
4. Run a hose from the needle valve to the hydrauluc filler

Fully open the needle valve and start the tractor. Then slowly close the needle valve while watching the gauge. Pressure will begin to climb as you clise the valvr. Stop closing the valve when you get to 2700 PSI.

Dan

Perfect, make sense to me. I think we have all of this at the shop. Will look in the morning. Thanks again for your help.