Lets talk lifts, used Rotary PFX1
 

So I bought a low-rise scissor lift off CL last week.
http://forums.pelicanparts.com/uploa...1446335851.jpg

It was $500 and the guy delivered it to my house.

I bought it out of a field, fluid reservoir open to the elements--so I was not optimistic it was going to be plug&play.

I emptied the tank and replaced with fresh fluid.
The unit will go up and down, but just barely. The system bleeds down with just the weight of the unit itself until the safetys catch it.

It would not hold any significant weight, so I took it apart to find two internal seals had pretty much disintegrated.
Here is where they were, I had already cleaned up the debris on one side.
http://forums.pelicanparts.com/uploa...1446335580.jpg
Here is what was left of the aforementioned seal:
http://forums.pelicanparts.com/uploa...1446335661.jpg

I cannot see much else out of sorts or any other problems. Can the pump internals fail in some way that is not externally observable? Any other common MOFs? I find it a little odd two little o-rings would render the thing inop--but then again it supposedly operates at 2300psi.

I already ordered the seal kit--so hopefully that fixes the problem.

Picture of power unit, I think it is a Rotary PFX1 lift, but I really have no idea as the ID marks are nowhere to be found on the lift and the pump ID plate has faded into nothing.

http://forums.pelicanparts.com/uploa...1446335876.jpg

Lol, I'm still trying to convince my wife it was a good buy.

Glad you got a chuckle out of it. I don't know much about them other than it would be nice to be an owner. Are you a member of Garage Journal? There is lot's of experience over there with lifts...

Yes, although I don't frequent the site too much. I'll go poke around! Thanks

The cylinder seals may be shot - bypassing fluid. There's no fluid coming out the top side?

No, cylinder has no leaks at the top or bottom. Not sure if I want to attempt to take it apart as of yet. I have ordered some new lines to take that out of the equation and just for peace of mind.

There is a relief valve that can get stuck open by debris, and will cause the lift to sink down, and not hold. Should be right on the side of the pump body. I had my lift do this, and it scared the bejesus out of me. I almost lost a car. I removed , and cleaned the valve, and it has been working for 3 + years since then. Good luck

Thanks for the suggestion Fastfred. I actually read about the pressure relief valve getting trash stuck in it, or otherwise stuck open on another site--so apparently that is not uncommon. I currently have my power unit totally disassembled, so I'll make sure to give that are a thorough cleaning.

Certainly not trying to hijack the thread...

But my scissor lift has a foaming fluids problem. When I lower the lift it makes, kind of, an aerating noise - sort of like a milk foamer on a coffee machine, when I lower the lift. Foamed up oil comes out of the filler hole. It's not over filled because if it's less it won't lift the car all the way up. I changed the oil to the correct stuff and it still does it.

Any ideas?

Justin what fluid did you replace it with ? My lift I think uses ATF ? It sounds like you are on a good path to diagnose the problem. Once you have it up and running you will love it. I ended up recessing mine into the floor which makes it that much easier to use. Good luck with the repair.

I thought about that last night, but mine is only a low rise unit. I think its maximum lift height is only like 20". It I were to recess it to floor level, it would not give me much space to work with. I know some of these lifts go much higher.

I refilled with ATF DEX II which is about the only legible thing on the side of the power unit.

Bill, I obviously know little about these things, but it seems I have read about fluid aeration. Somehow air is becoming mixed with your fluid. It could be that your soft lines have aged to a point they are semi-porous, shaft seal on the piston(s), or some other worn seals. At any rate, you might want to go through your unit too. What you have is entrained air, not just pockets that are bled out under normal operation at the valve.

Here is a little light reading: Symptoms of Common Hydraulic Problems and Their Root Causes

Thanks Justin.