Bed won't go up, can anyone help ?

[texasjohn]

If fluid is whitish/gray, not regular hydraulic color, then that is your problem....it's gumming the works up somewhere... I can almost guarantee that if you take things apart, insure free fluid flow everywhere, clear properly colored fluid everywhere, then all will begin to operate properly. that's the way it was with me.

 

[Rat Rod Mac]

Old Bones, instead of a cable mine uses a 3/8 diameter rod that is fastened to the lever in the cab. So no problem activating the pump valve.

John Texas, flushing the pump and cylinder and replacing with fresh fluid is a good idea. I don't think it has ever been done and condensation has to have taken effect over the years to some extent.

I think since I have the pump out of the truck I will try and find a place that will pressure test it before I go any further. Is it possible to flush the cylinder while it's still in the truck? Or do I have to take it out of the truck and disassemble it? Thanks again. RRM

 

[Gary Fowler]

If it is like you say, then a flush should be easy IF you can move the cylinder by hand. IF not then you may have to make your own reservoir for new oil and let it suck in the new stuff while pushing out the oil into a bucket, then let the hoses drain good and reverse the set up. One cycle should push most of the old oil out. You would need to disconnect it from the bed and lay it on the ground unless it has a way to cycle thru with one end disconnected. I dont think you would want to jack the bed up while working on the cylinder.

 

[texasjohn]

Don't exactly know your physical setup, thus can't advise specifically how to clean out/flush.

Yep, pressure test would verify that pump is capable of necessary pressure. In my area I found a shop that works exclusively on hydraulic systems and cylinders. Maybe there is one in your area as well.

In my case, I was amazed. Fluid was discolored, but physically seemed plenty fluid. However, the restriction/strainer caught a bunch of "curds" and was REALLY restricting the flow. Pump would have passed pressure test on a bench, but could not deliver fluid thru the restricted strainer...which was a coarse wire net...just FYI.

 

[wdchyd]

Rat Rod,

Your setup is more common than you think......Yes the reservoir is in the rod side of the cyl when collapsed......

The cyl is still single acting as gravity down....

You gonna have a problem testing that pump of the truck, the best way is to put the pump back on, fill with hyd oil, with truck off, operate the control valve (as if it was suppose to raise)........then use an alternate lifting source (forklift, backhoe ect) to lift body slowly, then release the control valve to neutral to hold the body to see if it stays up......

If it stays up then the cyl is OK and your pump is the problem.....

Sometimes the seals (or cast-iron piston rings) internally fail and the pump is trying to lift body but the oil just by-passes inside from the pressure side to the reservoir side of the cyl so the body does not go up.....

The best way to test pump is with one of these...Kubota Flow/Load Meter Test - Tractor Videos - Kubota, John Deere, New Holland and More

Bill