Case 580SL high circulation pressure

[Eric Martin]

Hey guys, I have a problem on a 580SL. The engine and hydrualic system were running hot and the engine was lugging down to much. Fuel system seems alright, so I threw a gauge on the hydraulics and the circuit pressure with all the functions in nuetral position the psi is 500 to 550 at an idle. When I acelarate, the psi also goes up? I couldn’t find an exact psi that that reading should be. Also there is a valve or something that gets stuck when I operate any of these three functions backhoe swing ,extendahoe, or steering. When I operate any of those they operate fine and have good psi, but when the spool goes back to nuetral the psi stays up at 1,800psi and slowly drops back down over about a 10 second time. I will get a serial num. As soon as I get to the shop

 

[Eric Martin]

Any help on this?

 

[alrman]

I don't have a direct answer for you.
But, the pressure with all levers in neutral position should be zero.
Does your machine have an auxilary control lever at the BH controls? With a swing around locking plate? - The locking plate should be turned away from the lever..... Just thought I'd mention that as it is a common issue.

If all levers & pedals 100% in their neutral positions & no electrical divertor valves have been fitted & are activated, I would be looking at the steering priority valve/spool which is in the inlet section of the loader control valve OR the swing sequence valve on the backhoe swing tower.

I would imagine if either of these were to blame, they would develop some heat fairly quickly.
So, using an infrared heat gun when you start the machine from cold, will show a rapid difference in temp.

 

[Eric Martin]

So in the circuit, back thru the backhoe valve and front to the tank, you do t think I should get any readable psi?
I was going down more the row of obstruction or clogged passage way…..
Thanks for your reply….it will give me some areas to try
I will keep you posted

 

[Eric Martin]

So here is the flow divider spool….from the loader valve. It has scratches the whole way around I’m. Is that enough to cause the issue

 

[Eric Martin]

ok it seems to be all the same problem. when i opperate any of these 3 functions the e-hoe, swing, or the steering. the two worst are the e-hoe and the swing. if i start to move the spool just a little even before the swing starts to move it lugs the engine down and you can here the relief open above the flow divider. i adjusted that relief the whole way in and it makes the problem much worse i can stall the engine just by moving the spool a little even before the swing starts moving. if i rev the engine up good the pressure goes up to 3200 psi even before the swing starts to move. once the spool opens the pressure drops and the swing will work normally until i leave off and go the other way and the pressure spikes and relief opens. i polished those scratches on the flow divider spool and put it back in...it moves freely and it didnt make a diference