I need some old pro to tell me what I'm missing. Got a Lull, AKA Prime Mover skid steer with a Sauer-sunderland Series 40 M46 hydrostatic pump system. Has been a great machine. Stopped moving after getting heat temp light on hydraulics. I knew the pump needed overhaul. Sent it to Hydrostatic Trans LLC in Tupelo. They did a full overhaul and returned the unit. Installed and got no pressure to the drive motors. Arms and tilt worked fine. The implement pump was obviously working. But I was getting extreme back pressure into the oil tank. Andy at Hydrostatic said it must be running backwards so I sent it back to Tupelo. Got it back, put it in and got same problem minus the back pressure. I sanitized the hydraulic system and added all new hoses and o-rings. Cleaned tank and installed fresh oil and filter. Gauze metal filter in tank is clean. Pump will not create flow to drive motors. I don't have or even know for sure how to check the charge pressure which is the logical next step. If I can't get this figured out Andy has offered a full refund with the return of the transmission. And I guess I'll part out the rest of the machine. I hate to see it go but I've spent 2k trying to fixit so I got to cut my losses. Anybody got any suggestions.
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antfarmer2
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Does it have drain case filters
antframer2, The only filters I've seen are the big quart size canister back by the hydraulic oil cooler and the metal gauze filter in the suction side of the tank. I actually have a exploded view of the pump but I see no filter there. Where would the drain case filter be. BTW, I cleaned the oil cooler as well and it is flowing fine.Does it have drain case filters
antfarmer2
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The cooler was to be my next? ....look for a metal cylinder on the hose off the drive motors might be one on each side not sure but have heard of such thingsantframer2, The only filters I've seen are the big quart size canister back by the hydraulic oil cooler and the metal gauze filter in the suction side of the tank. I actually have a exploded view of the pump but I see no filter there. Where would the drain case filter be. BTW, I cleaned the oil cooler as well and it is flowing fine.
Nothing like that on any of the four lines running from pump to drive motors. Looking at the hydraulic schematic their appears to be no other filters. I think it has got be something wrong inside that pump.The cooler was to be my next? ....look for a metal cylinder on the hose off the drive motors might be one on each side not sure but have heard of such things
antfarmer2
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Just shot gunning here have you cheaked for pressure and blocked linesNothing like that on any of the four lines running from pump to drive motors. Looking at the hydraulic schematic their appears to be no other filters. I think it has got be something wrong inside that pump.
antfarmer2
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Maybe a cloged vent capJust shot gunning here have you cheaked for pressure and blocked lines
Pretty sure everything is open. I'm just stumped.Maybe a cloged vent cap
antfarmer2
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Crack a line and put light pressure in the tank to bleed out air of the whoe system line by lineMaybe a cloged vent cap
antfarmer2
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I will keep thinking but a lot of great minds in here have too wait for a better one if none of this worksCrack a line and put light pressure in the tank to bleed out air of the whoe system line by line
antfarmer2
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Maybe lift it up to help bleedI will keep thinking but a lot of great minds in here have too wait for a better one if none of this works
Nothing to lose at this point. I'll give it a try.Maybe lift it up to help bleed
antfarmer2
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That's me cheap and easy let me knowNothing to lose at this point. I'll give it a try.
POssibly even try having the machine on blocks, remove a hose from each drive motor and operate the levers, see if you get oil out.That's me cheap and easy let me know
The pump should be a piston pump, so even if they installed the wear plates (if fitted) it will still generate pressure, but possibly not enough. So i can't see that they have messed up with putting it together. Have you checked for any rotation marks on the pumps to confirm that the engine is rotating it that way? just to be sure. If the gear/vane pump was backwards it could cause this issue, but if your lift and tilt work, it seems it's rite.
Charge pressure, you *may* be able to check it at the filter, there may be a pressure sensor either on the pump or around the filter that you may be able to tap into and install a manual guage.
Most systems on skid steers are pretty well the same. Oil goes from the main hydraulic pump to the control block, out to the oil cooler/filter back to the hydrostatic pump to generate charge pressure, the rest goes back to the tank/main hydraulic pump.
Could a hose be wrong? are you getting oil to the oil cooler/filter? is there a hose from the cooler to the pump?
Sadly i have never worked on one of these, so i'm working from what i remember of bobcat machines. It's a good guide, but there are always subtle differences.
I put it up on blocks but no joy. no pressure going to wheel motors. This machine has a peculiar arrangement of the hoses in the cooler filter area. The line coming from the block runs into a union that included the cooler and pump lines. Very little flow to that union from the block. The control block is sufficiently pressurized to work the arms and tilt beaucoup. I just wonder if there is a blockage in the block restricting flow out to the filter/cooler union. Thanks for your suggestions. I got a feeling the charge pump is not doing it's job.POssibly even try having the machine on blocks, remove a hose from each drive motor and operate the levers, see if you get oil out.
The pump should be a piston pump, so even if they installed the wear plates (if fitted) it will still generate pressure, but possibly not enough. So i can't see that they have messed up with putting it together. Have you checked for any rotation marks on the pumps to confirm that the engine is rotating it that way? just to be sure. If the gear/vane pump was backwards it could cause this issue, but if your lift and tilt work, it seems it's rite.
Charge pressure, you *may* be able to check it at the filter, there may be a pressure sensor either on the pump or around the filter that you may be able to tap into and install a manual guage.
Most systems on skid steers are pretty well the same. Oil goes from the main hydraulic pump to the control block, out to the oil cooler/filter back to the hydrostatic pump to generate charge pressure, the rest goes back to the tank/main hydraulic pump.
Could a hose be wrong? are you getting oil to the oil cooler/filter? is there a hose from the cooler to the pump?
Sadly i have never worked on one of these, so i'm working from what i remember of bobcat machines. It's a good guide, but there are always subtle differences.
You had the hydro static pumps rebuilt? Not the charge pressure one? Can you take a picture or two that would show the general arrangement of the hoses? It is easier to post them in the media section if you have trouble with posting them. Can you take the output hose off the charge or implement pump and see first if it is moving oil, you said the lift works so disconnect one of the cylinder hoses put a gauge on it and see what pressure is there when it goes over relief. If you have pressurized oil coming from the charge pump follow the oil and disconnect hoses till you see where it stops flowing. I remember seeing on this forum where some systems need to be bled of air, it might have been case or older new Holland. The rebuilder must have faith in his work if he offered to refund the cost so hopefully it will be just air or as you said a blockage.I put it up on blocks but no joy. no pressure going to wheel motors. This machine has a peculiar arrangement of the hoses in the cooler filter area. The line coming from the block runs into a union that included the cooler and pump lines. Very little flow to that union from the block. The control block is sufficiently pressurized to work the arms and tilt beaucoup. I just wonder if there is a blockage in the block restricting flow out to the filter/cooler union. Thanks for your suggestions. I got a feeling the charge pump is not doing it's job.
Basically, the line out from control block connects to a crossflow union that also connects to a line that runs to pump, and 2 lines that run to and from the oil cooler. The filter is connected to the top of the pump via and dedicated in and out lines.You had the hydro static pumps rebuilt? Not the charge pressure one? Can you take a picture or two that would show the general arrangement of the hoses? It is easier to post them in the media section if you have trouble with posting them. Can you take the output hose off the charge or implement pump and see first if it is moving oil, you said the lift works so disconnect one of the cylinder hoses put a gauge on it and see what pressure is there when it goes over relief. If you have pressurized oil coming from the charge pump follow the oil and disconnect hoses till you see where it stops flowing. I remember seeing on this forum where some systems need to be bled of air, it might have been case or older new Holland. The rebuilder must have faith in his work if he offered to refund the cost so hopefully it will be just air or as you said a blockage.
antfarmer2
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Did you bleed the air out by putting light pressure in the hydro tank and cracking line by line yet? What kind of oil are you useing?Basically, the line out from control block connects to a crossflow union that also connects to a line that runs to pump, and 2 lines that run to and from the oil cooler. The filter is connected to the top of the pump via and dedicated in and out lines.
If a few pounds of air in the tank don't help you still have to start at the charge pump and follow the pressure by taking off hoses till you get to one that has no oil flow.Did you bleed the air out by putting light pressure in the hydro tank and cracking line by line yet? What kind of oil are you useing?