That charge pressure (20 under load) is right down at minimum, where the warning light should come on. My understanding is that piston pumps, like the ones in the hydrostatic drive, don't work well without proper charge pressure. Worse yet, I think they can suffer damage if operated that way for long. How about the hydraulic filter, when was that last changed? Yeah, there is a bypass there if it gets too dirty, but that opens at 25 psi, so you would lose that much charge pressure "right off the top" if it is dirty. With lines from the pump capped, virtually any movement of the levers should result in max pressure. I'll have to study the hydraulic schematic some more, try to figure out where to test to find out why the charge is so low.
Bobcat 743 not enough hydraulic power to push dirt or turn left/right
- Thread starter RusticRR
- Start date
Good idea, I will get a new filter ASAP.
Do you have a NAPA auto parts nearby? The hydraulic filter is NAPA "gold" 1482, the engine is NAPA "gold" 1068. Both are made by Wix, as I understand.
Yep, I will swing into a NAPA at lunch today, thanks!
I think you will be pulling the pump still. Those figures are very low, even if the oil was too thin, when cold, you should hold charge pressure pretty well.
If you decide to attack the pump, look up my profile and send me an email. I can send you details of what you need to do to get it back into shape.
Brianclements
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Hi new to this site but you just described my machine and hydraulic problem down to a t. I was wanting to as what was your final problem with it
Thanks to Tazza I was able to get it running without investing a ton of additional $$$. After I checked the pressure going to each drive motor and identified that they were both low, he knew it was definitely a problem with the main hydraulic pump. So I pulled it out and cracked it open and the problem became clear. Both of the wafer plates were badly scored.
My intent was to simply purchase new wafer plates, but Tazza said I could repair the old ones by simply sanding them down. The trick is to sand them on a very flat surface that does not bend. So I took the glass out of an old 10X14 picture frame and laid it on my bench. Then taped a sheet of 1000 grit sand paper to it. Then placing my palm flat on the wafer plate I pushed hard down on the plate and moved it in a figure 8 pattern. The sand paper will fill up fast with metal fragments. Don't change the sheet, simply spray it off with a garden hose and start all over again. It took me about an hour of continuous sanding for each plate to become groove free. Below is the "after" picture:
Brianclements
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At the risk of sounding dumb how did you get the wafer plates off the pump housing? Mine seam to be stuck on so I am afraid to try to force them off
I had that same question also, but you just take a small flat-blade screwdriver and gently pop them off. There is a small inlet hole on the manifold at the top of the plate that you can use. NOTE: do not get the plates mixed up. Make sure that you put them back on the side that they came from.
Brianclements
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Ok thanks so much I'm gonna give it a try
There is a small pin that locates them so they don't turn, a film of oil behind them holds them in place pretty hard, as stated, a screw driver will make it move.
