Rotary Lift Global Hydraulic systems help needed

[cardr]

I have a SPO7 that I just rebuilt the cylinder on. I actually rebuilt it twice because of this issue that I'm having to confirm that it's right. I have a Global hydraulics Pump P1352. I think this is a newer style pump. The problem is intermittent and doesn't happen all the time. It will pump sometimes and work, and then other times the pump will run and blow bubbles in the tank.

I've taken the entire pump apart, twice! Pump gears look great. I've disassembled every fitting, ball, spring and cleaned, and blown it all out looking for debris. I haven't found anything. The pickup tube is good. No cracks or holes that I can see.

It seems to me that the pump is losing prime. I've looked at several other Rotary pumps and most of them are different than mine....imagine that! Mine has extra check valves, pressure relief valves that other pumps don't have. I'm trying to troubleshoot this pump, but can't find anyone with these parts that I can swap out to see what the issue is. Some of these valves are hundreds of dollars.

Does anyone know what these valves in the pictures are and if I can bypass with plugs to see if these are the issue? I know the one on the side with the lines is the pressure relief for the rating of the lift. I have another older spring and assembly that I'm going to try. Just curious about the others, and/or if anyone has had this issue before.

I have a video of it blowing bubbles then working, but not sure how to attach that.

Thanks,
Doug

 

[BlindViper]

Did you clean the check valve very well? Does it built pressure and hold a vehicle up?

 

[cardr]

When you say check valve do you mean the release to lower the lift? If so yes....but now come to think of it I think it was lowering by itself....

 

[pertality]

The logo on the lowering valve is Bucher Hydraulics. Their UP series power units seems similar to what you have

The catalogs are pretty decent for seeing how they work with schematics and decent cross section.

UP series power units

 

[cardr]

Awesome. Thanks for that info I'll have a look. Much appreciated!

 

[finn]

Bubbles in the outlet mean a suction side leak, but I think you already know that.

 

[cardr]

Bubbles in the outlet mean a suction side leak, but I think you already know that.

Well, the bubbles are inside the tank.....not sure if it's from the pickup, or somewhere else. Somewhere that's under the fluid, because of the bubbles, it's not just air....

Doesn't make sense to me.

 

[BlindViper]

When you say check valve do you mean the release to lower the lift? If so yes....but now come to think of it I think it was lowering by itself....

My lift was lowering itself, but it also sounded like the pump/motor was spinning. My check valve had a piece of something stuck in it. This caused fluid to go back through the pump making it spin backwards and letting the lift drop.