MaxJack alternative power units?

[Christos]

Hi MaxJack owners,

Has anyone used a different power unit on the lift? I bought my lift from someone who had stored and never used it. After I installed it the power unit seems defective, it does not produce enough pressure to lift. The lift is out of warranty and the company will not do anything about it, except sell me a new unit for $500.

Has anyone tried to repair these units or use a different unit? I see a few available for under $250.

Any advice appreciated.

Christos.

 

[gerryw]

Did you check if the release valve is stuck ( were the lever pushes in)
Yes you can buy a universal unit ( just match hp/volts to yours) i used one on my my dannmar scissor lift (same power unit as yours) Hydro-tech ( korean i believe)

Gerry

 

[Hop2it]

I am using a harbor freight unit I bought my maxjak new before the floor was poured so I could put the rebar out of the way of the anchors,then decided to wire the barn insulate,drywall and paint before installing lift.that put me beyond the one year warranty 1st car up would not go down evenly thought was going to land on is side at one point,about 4 hours later got it down,customer service said I used the wrong grease cleaned it out and used white lithium grease.then I had problems getting
G it to go up evenly had to replace the splitter valve,then I struggled to get it to go up at all replaced capacitors no luck new pump unit from maxjak $460 from harbor freight about $260 with shipping, it finally works but has left a sour taste in my mouth for anything “danmar”
Doug

 

[Oilguy]

Will it not raise the lift with no load on it?
Does the sound of the motor change when you try to raise the lift?
GerryW made a good point on the release valve. If a check valve stuck open, there will be no change on the electric motor load when you operate the valve. There will also be a relief valve in the control block you may want to check or adjust. You could also have a coupling between the pump and motor which someone forgot to install.
If you can, tell us about any changes in sound when you operate it.

 

[Christos]

Thanks to everyone who replied! Here is some more information.

Initially, the lift would not raise the car (a '94 Altima, weighing about half of the lift's rating of 6,000 lbs) mor ethan a few inches from the ground. Without a car, the arms would rise all the way to the top, which allowed me to bleed the cylinders.

I took the power unit to a heavy equipment repair shop and they managed to crank up the pressure by adjusting a valve to about 1200 psi, still well shy of the 1920psi the unit is rated. The lift would now raise a lighter car (An MK1 Jetta) very slowly to the top. I don't believe it would raise our minivan at almost 6,000 lbs. So while better, problem not solved.

You asked about the noise: it does not change at all throughout the lift cycle. I cannot hear the lift working harder when lifting a car. Does this indicate a leaking valve?

When I stop lifting, the car will stay put, there does not seem to be an internal leak. The car will come down reasonably fast when I press the release valve.

Is this enough information for a reasonable diagnosis? I am pretty handy when it comes to car repair, should I open up the unit to see what's going on? Or should I just look for a new power unit?

Thanks!

Chris.

 

[Christos]

I can certainly relate to your Danmar customer experience. Some customer representatives were more helpful than others, but at the end they would not do anything for me either.

Which unit did you buy from Harbor Freight? it appears they are not selling any hydraulic power units anymore.

Chris.

 

[brownbagg]

the bendpak two post use a model made by stone mfg.

 

[shaggyant]

I can certainly relate to your Danmar customer experience. Some customer representatives were more helpful than others, but at the end they would not do anything for me either.

Which unit did you buy from Harbor Freight? it appears they are not selling any hydraulic power units anymore.

Chris.

Would this work?

https://m.harborfreight.com/1-hp-electric-hydraulic-pressure-pump-46169.html

 

[txvwnut]

Take your pump back to the hydraulic shop and have them set the relief to the pumps max pressure rating. What’s most likely happening is it’s tipping the relief valve while it’s raising under load and bypassing some of the fluid back to tank causing your slow lift time.

 

[Christos]

Take your pump back to the hydraulic shop and have them set the relief to the pumps max pressure rating. What’s most likely happening is it’s tipping the relief valve while it’s raising under load and bypassing some of the fluid back to tank causing your slow lift time.

That's exactly what they did. They set the relief valve for max pressure, but it was still well below the operating pressure for the unit. This was without opening the unit for further examination/repairs. At $100/hour they correctly said the repair may easily exceed the price of a new unit and there is still no guarantee they can fix it.

Chris.

 

[Muc]

should I open up the unit to see what's going on?


Chris.

Of course you take it apart. This is the GJ. Got nothing to lose at this point.

Does the fluid foam in the tank when you try and lift something heavy?
Might be something simple like a restricted suction filter.

 

[Oilguy]

Do as TXVWNut says and raise the pressure to where ii is supposed to be. In a hydraulic system, Force = pressure x area of the cylinder piston. If you are 600 PSI short, that is a lot of force. If your lift has 2 cylinders, that is a bunch. The force output of a 4" bore cylinder at 600 PSI is 7536 lbs for example. Working angle has an affect on the force but you are probably way short. "More pressure captain".

 

[Christos]

Thanks guys, I will start taking things apart and see what I find. I will check for foaming first in case there is a leak or a crack in the pickup tube. Then I will go into the pump itself. Correct me if I am wrong, but the fact that the noise from the motor does not change under load tells me there is a leak somewhere.

A couple of reasons I haven't opened it yet: (a) while I am comfortable working on cars, I have never touched a hydraulic unit such as this one, there are very high pressures involved, but I assume with care and common sense I should be able to work on it; and (b) with the relief valve maxed out, I need to readjust the pressure back to a safe limit. I bought a 5,000 psi gauge and it would be great to attach it somewhere to monitor the pressure. Is there typically such an attachment point on these units? I am hoping to leave the thing attached permanently.

Thanks again folks!

Chris.

 

[Muc]

Most I have seen are just T’d into the output.
Leak or restrictions on suction side, pump bypassing internally, pressure relief is weak.