John Deere Grader 770G - constant pressure in Load sensing Line

Good day everyone

I'm dealing with a problem on my John Deere Grader. There's constant pressure showing up in the load sensing line, and it's making the pump work too hard and overheat. I'm getting constant flow from the steering valve and both the left and right direction control valves. I adjusted the flow-reducing-valve in the combination valve on the hydraulic manifold, and the steering valve sorted itself out, but those two control valves are still producing pressure. I also looked at the load sense relief valve, but I can't adjust it - nothing moves and I'm not sure how it's supposed to work or if it's stuck. The machine plate number is DW770GX625066. Has anyone run into this before or have a hydraulic schematic? Any help would be really appreciated.

Have you looked at the system relief valve #11? It should only crack open when standby pressure gets too high to protect the pump and other parts. A bad o-ring or broken spring in there could keep the pump in stroke, which would explain the overheating you're seeing. Might be worth checking out.

Thanks for the input, I'll give that a try and report back. There's constant oil flow in the load sense line when there shouldn't be any unless the lever is actually being operated.

I really appreciate all the help and insight everyone on here provided. I'm grateful to be part of this community and thankful to everyone who replied to my original post.

I'm happy to say the problem is fixed now.

If anyone runs into the same issue, here's what I did:

Connected a pressure gauge to the pump output. Adjusted the pressure reducing valve. Watched the pressure come down from 1500 psi to 500 psi (the system had been running at 1500 psi initially). Adjusted the load-sense relief valve until the max operating pressure hit 2000 psi.

The machine runs fine now.

One thing I'm still wondering about though - why did Deere put a load-sense relief valve in the system when adjusting the pressure reducing valve and load-sense relief valve seemed to do the same job as tuning the load-sense and pressure compensator spool?

Thanks again everyone.