Case 580 - where is the oil pressure regulator?

RayCo · May 23, 2023

Y'all. My 1998 Case 580 Super L has low oil pressure at idle. From things I've found elsewhere, this seems not too uncommon, and I read about it can often be a simple fix of cleaning gunk out of the oil pressure regulator. What I haven't been able to find, however, is where exactly that is and what it looks like. I have the service manual for this backhoe and it does verify the existence of this in the description of the oil flow, but there is no mention of it in any of the servicing steps, such as simple oil changes or replacing the oil pump, etc. Is there anyone familiar with this engine (4-390) and the pictures below who can say, "See that thing there, that's what you're looking for." Before taking things apart, I want to try to make sure I'm targeting the right thing and can get any necessary gaskets I might need before disassembly.

TractorTech · May 23, 2023

See that there?

RayCo · May 24, 2023

Thank you. I was eyeing that up, but in the service manual, that's the pressure relief valve. In my mind, that's there in situations of "Oof, oil pressure is too high, so this will open and let the oil relieve its pressure there," like the relief valves on hydraulics. No? Either way, I'll open that up and make it great again and see.

TractorTech · May 24, 2023

Essentially, that is exactly how it functions. A relief valve relieves pressure at a predetermined pressure so that the oil system, hydraulic or lube, is not damaged. The pressure is created by flow. If the flow is bypassed, say by a stuck open relief, then pressure is not created. Looking at for a stuck relief is about the only thing that will all of a sudden create low pressure.
If over time the pump has worn, then the pump will bypass oil rather than pump it and create low pressure, but this is not an all of a sudden condition. Also, does not usually happen on engines oil pumps. Hydraulic pumps, yes.