L783 hydraulic issues

[Davidvan326]

I have a 94 L783 that becomes sluggish to the point of not moving. When the machine is cold it will drive and bucket will work fine. As it warms up, approximately 5 minutes, the bucket gradually gets slower and slower to the point of not moving. The drives will work fine as the bucket gets slower until the bucket won't move, then the drives start giving back pressure on the levers and machine will barely move. It has plenty of fluid. Any ideas where to start? Thanks

 

[Tazza]

Working when cold, but slowing down when warm or hot is generally due to pump wear.
The only way to know for sure is to get it tested, they can check flow and pressure to see if it is within spec.

 

[Davidvan326]

Working when cold, but slowing down when warm or hot is generally due to pump wear.
The only way to know for sure is to get it tested, they can check flow and pressure to see if it is within spec.

I was thinking that at first but why would all three pumps fail at the same time? Could filters cause a similar issue?

 

[Mike10]

I was thinking that at first but why would all three pumps fail at the same time? Could filters cause a similar issue?

It is not all three pumps, but the main hyd pump. The hyd pump suuplies the charge pressure to the hydrostat pumps throught the return circuit of the hydraulic pump. There is not a separate charge pump on this loader as with many hydrostats. Your charge pressure light should be coming on and the alarm sounding, that is if they are working.

 

[Davidvan326]

It is not all three pumps, but the main hyd pump. The hyd pump suuplies the charge pressure to the hydrostat pumps throught the return circuit of the hydraulic pump. There is not a separate charge pump on this loader as with many hydrostats. Your charge pressure light should be coming on and the alarm sounding, that is if they are working.

Thanks for the reply, I had no idea that was how it worked... As for my charge light, none of the warning lights were working when I bought the skid steer, probably need to fix that one day. I did some research on charge pump and circuits so it's making a little more sense now. I'm assuming that the "gear pump" is functioning as a charge pump for the system. My budget will only allow me to either get the replacement pump or get it "professionally" diagnosed..... but, not both. So looks like I will order a pump and roll the dice that it is my problem.

 

[pupp]

Thanks for the reply, I had no idea that was how it worked... As for my charge light, none of the warning lights were working when I bought the skid steer, probably need to fix that one day. I did some research on charge pump and circuits so it's making a little more sense now. I'm assuming that the "gear pump" is functioning as a charge pump for the system. My budget will only allow me to either get the replacement pump or get it "professionally" diagnosed..... but, not both. So looks like I will order a pump and roll the dice that it is my problem.

Hi just bought a NH L783 have same problem. Have you checked the hydraulic screen under the seat. It is to the right as you look from standing in front of the machine. it is in a cylinder with a 7/8" cap has a magnet and screen inside. mine looked like it was never cleaned. I cleaned it and put it back in and worked great for 1 hour then clogged again now have to change oil. looking for the hydraulic plug.Any help appreciated.

 

[Davidvan326]

Hi just bought a NH L783 have same problem. Have you checked the hydraulic screen under the seat. It is to the right as you look from standing in front of the machine. it is in a cylinder with a 7/8" cap has a magnet and screen inside. mine looked like it was never cleaned. I cleaned it and put it back in and worked great for 1 hour then clogged again now have to change oil. looking for the hydraulic plug.Any help appreciated.

I did check the screen filter and it did have some gunk on it but it was the pump. Relplaced it and all is good again.