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Well, I guess one, with some efforts, can turn a ‘little bit broke’ into a ‘fubar broke’.........or so I have heard.
ChoppyChoppy
Tree Freak
Words I have lived by! LOL
My Dad used to tell us (My brother and I)... "you just had to fix it until you broke it huh?"
You're not understanding how these pumps work. There is a low volume and a high volume section to the pump. (For illustration- let's say the low volume section outputs 4gpm, and the high outputs 12gpm)
There is an unloader valve on the high volume section. It's adjustable as you found, from ~400-800psi.
Your system also has a relief valve, usually set at 2250-3000 psi.
At any time - the actual pressure in your system is dependent on the load on the cylinder.
- Under no load conditions- lever centered, both sections of the pump contribute to the total output. Total flow is 4+12=16gpm. Pressure is just the backpressure from the hoses, valves and filter. <50psi
- When the cylinder is advancing - light load - both sections again contribute to the total output. Total Flow = 16gpm. Pressure is higher to move the cylinder or start the split. Say 100-250 psi
- When the load on the splitter gets to the point that the pressure hits the unloader setting, the high volume section of the pump bypasses, and only the low volume section delivers fluid to the splitter. Flow = 4gpm. Pressure = 600psi +/-
- As the load increases beyond the unloader setting, the output remains constant at 4gpm, and the pressure will depend on how tough the piece is, but won't exceed the system relief pressure.
Engine load is dependent on flow x pressure. Exceed the engine output and it will stall. There are 2 cases where the engine will stall.
- If the unloader pressure is set too high, then the load on the engine can exceed the engine output and stall the engine BEFORE the pressure reaches the setpoint where the pump unloads the high volume section. (low + high vol) x unloader > engine output
- If the system relief pressure is set to high, then the engine may also stall. (low vol ) x system relief > engine output
Given that you're stalling at under 800psi, then it's the former. Turn the unloader screw way out (lower pressure) until the engine doesn't stall and you should see the pressure climbing beyond 1000psi.
I'm guessing that the unloader pressure is set too high, and that's why you're stalling the engine.
Excellent post for the two stage explanation.
My understanding of his question is that the final pressure does not reach the RV setting of 2500-3000. He only reaches 600-800. Adjusting the unloading pressure up and doesn’t solve the problem, and can lead to engine stall as you wrote, but it is a way of diagnosing why the final pressure won’t reach RV, even with the cylinder plugged off IIRC.
If the check valve is bypassing back and not isolating, the gauge pressure will go up or down with the adjustment of the unloading valve, which is what I wanted to find out.
Although I am very aware that remote diagnosis depends on people understanding and using the words exactly the same as each other.
Did that for 35 + years and the most difficult part was defining the words and making sure both parties were asking/answering what the other person thought they were saying......
My understanding of his question is that the final pressure does not reach the RV setting of 2500-3000. He only reaches 600-800. Adjusting the unloading pressure up and doesn’t solve the problem, and can lead to engine stall as you wrote, but it is a way of diagnosing why the final pressure won’t reach RV, even with the cylinder plugged off IIRC.
If the check valve is bypassing back and not isolating, the gauge pressure will go up or down with the adjustment of the unloading valve, which is what I wanted to find out.
Although I am very aware that remote diagnosis depends on people understanding and using the words exactly the same as each other.
Did that for 35 + years and the most difficult part was defining the words and making sure both parties were asking/answering what the other person thought they were saying......
Sounds like marriage...
Robb, after rereading all your posts it sounds like the pump is operating as it should. It is can produce 3000 psi when enough resistance is met. The engine seems to be working properly.
Other possible causes could be a soft suction hose that is collapsing or partly blocked which would starve the pump of fluid. A clogged vent on the hydraulic tank could also restrict flow to the pump. These items could cause intermittent problems. If none of these problems exist then I would assume the piston seals inside the cylinder are worn.
Other possible causes could be a soft suction hose that is collapsing or partly blocked which would starve the pump of fluid. A clogged vent on the hydraulic tank could also restrict flow to the pump. These items could cause intermittent problems. If none of these problems exist then I would assume the piston seals inside the cylinder are worn.
After following the helpful advice so many of you offer and checking pressures and such and after surviving the holidays, I replaced the pump on the splitter. But, it kind of fixed one problem and brought about another. Before, it didn't have enough power to split anything. Now, I can split some soft logs like cherry. But, harder stuff barely dent's and stalls the engine. It doesn't seem like it's changing from low to high pressure. Do I need to adjust something?
What pressure readings are you getting? At what pressure does the engine stall?
And the saga continues. The new hydraulic pump that I got on line works fine. That is, once I tweaked the adjustment screw on it. At first, it stalled the engine. So, I got the splitter going and tried to split some wood when it was cold out and another problem popped up. It started leaking engine oil. At first I that the engine had blown seal because it was steadily losing oil as it ran. But, when I took the shroud off, there didn't appear to be any leaks there. So, I degreased the engine and rigged up the fuel tank so I could inspect the engine while it ran. Strangely, it turn out that the oil was shooting out a hole in the plastic dipstick tube right at the bend where it was spraying on the engine. I never had that problem before.
I can fix a leaky dip stick tube. But, I was wondering if it was normal for the oil to spray up that tube while the engine runs or if I should be looking for an additional problem like a crankcase breathing tube clog?
I can fix a leaky dip stick tube. But, I was wondering if it was normal for the oil to spray up that tube while the engine runs or if I should be looking for an additional problem like a crankcase breathing tube clog?
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