Scissor lift - strange hydraulic problem.

[Bill Douglas]

My unbranded (Chinese) lift that looks like the BendPak MD-6XP has always had a problem of overflowing hydraulic fluid from the filler hole/breather on the oil reservoir when it is lowered.

After reading this thread and looking at youtubes I raised the side with the bleeder so the air runs upwards, opened the bleeder and ran the pump. About three liters of foamy ISO-46 hydraulic fluid came out. Very creamy, aerated , looking. Looked like the top of a good latte.

Umm, I can't figure out why or how the air is getting in, or why it's getting aerated. the lift works well other than the overfowing problem.

Any ideas?

[908/930]

Possibly just too much oil in res, these cylinders leak oil past the cylinder seals that works its way back to the reservoir when cylinder is activated, I think air gets into the back of the cylinder when it is lowered.

[philip j]

I had that happen to me once also.. I had the brain fart to top up the reservoir, but the lift wasn't completely down, when I did lower it, I had the same air filled hydraulic fluid overflow as you have...

[Bill Douglas]

Haha, that's pretty funny Philip, the sort of thing I would do. 908, I've got the level correct as per the dip stick, but I'll try it lower.

It really makes some noise when lowering is almost complete (another clue?) and sounds just like the milk frother on the espresso machine.