Oliver 550 Hydraulic issue

[msellers]

I have an Oliver 550 that the hydraulics' were getting weak so replaced the hydraulic pump, filter and loader external valves. Everything worked normal for maybe 2 months and has good pressure. After the 2 months the issue is when I first start the tractor there are no hydraulics', loader or 3 point lift arms. But then in 2 to 5 minutes it all starts working normal, no abnormal noise or anything just starts working. Does not matter if I hold a loader valve open for this 2 to 5 minutes or just wait it out. This issue has been going on for about 3 months. Any ideas as to what could be causing this? I will add once the tractor is started in the morning you can turn off and hour later restart and it works normal. Seems it must set overnight to create this condition

 

[stevieb49829]

I have an Oliver 550 that the hydraulics' were getting weak so replaced the hydraulic pump, filter and loader external valves. Everything worked normal for maybe 2 months and has good pressure. After the 2 months the issue is when I first start the tractor there are no hydraulics', loader or 3 point lift arms. But then in 2 to 5 minutes it all starts working normal, no abnormal noise or anything just starts working. Does not matter if I hold a loader valve open for this 2 to 5 minutes or just wait it out. This issue has been going on for about 3 months. Any ideas as to what could be causing this? I will add once the tractor is started in the morning you can turn off and hour later restart and it works normal. Seems it must set overnight to create this condition

I'm unfamiliar with this tractor, but is the reservoir below the pump, so the pump COULD drain back to the reservoir as it sits? If that's the case, you'll have to find where the air is coming from that allows the pump to drain its fluid back to the reservoir. Suction will usually keep it in place. If you don't have any obvious leaks, your loader valve check valves are probably the culprit, letting the oil pass back though the valve while at rest, and drawing air back through the return-to-tank. Of course, I might be way out in left field, too. steve

 

[msellers]

Pump is below the reservoir so always has oil. This is a strange issue but maybe you are on the right track on the valves. This is an open center hydraulic system and I am thinking maybe it is the external valve assemble. I have learned (hopefully correctly) that oil flows through this valve continuously and then gets diverted when the spool valve opens when you raise the loader or such. I have the cad drawing of the valves and there are poppit valves above each spool valve. It is a Prince company valve. Still open for ideas as I am still guessing.

 

[stevieb49829]

Is there a screen inside the reservoir, ahead of the suction outlet that could be partially plugged? And I'm assuming the filter you changed is in the return line? Also, can you put a gauge on the pump outlet side to check pressure when you first start it? There should be some, but not much when you are not using the valves, and it should jump up as soon as you try to move one of the functions. If it doesn't change during valve operation, your pressure relief valve in the spool valve is sticking open, allowing the oil to return to tank without creating any pressure. Post your CAD drawing of the valve, and maybe we can get some more ideas of what is going on. steve

 

[msellers]

I will put a gauge on and see. This may take a few days as we have generator off getting fixed currently. Attached is the cad drawing of the valve. I do not think it can be the screen as the transition from not working to working is seamless. I called tech support where I bought the valve (Surplus Center) and the young man first said my oil was worn out and needed replaced then told me my reservoir was too small. I was nice to him as he knew less than me on the subject. Appreciate you help

 

[Jim.ME]

I will put a gauge on and see. This may take a few days as we have generator off getting fixed currently. Attached is the cad drawing of the valve. I do not think it can be the screen as the transition from not working to working is seamless. I called tech support where I bought the valve (Surplus Center) and the young man first said my oil was worn out and needed replaced then told me my reservoir was too small. I was nice to him as he knew less than me on the subject. Appreciate you help

You might try asking this down below on the Oliver, Cletrac, Co-op and Cockshutt Discussion Forum this site has. There might be an Oliver guy or two there that don't check this site out often. You are using the tractor's internal pump and hydraulics, not a front mounted pump, correct?

 

[msellers]

You might try asking this down below on the Oliver, Cletrac, Co-op and Cockshutt Discussion Forum this site has. There might be an Oliver guy or two there that don't check this site out often. You are using the tractor's internal pump and hydraulics, not a front mounted pump, correct?

Correct, internal pump. Thanks