tow truck problems

Can you crack the hydraulic lines loose and run it up & down to see if any air comes out?

 

Make certain the belt is not slipping when under a heavy load. It takes more pressure/force, to lift the bed and stinger up than to simply slide them.

 

First make sure the load isn’t slipping the belt on the pump. If that’s good I’d say you could have a problem in the spool block. It works with the spool on that circuit cracked open but not at full stroke. You may have a damaged spool or o-ring that by-passes to the return circuit or the relief when the spool is all the way open, or pressurizing both sides of the cylinder at the same time. If it’s cylinder locked like that I’d you’d hear the pump load up and slip the belt. Assuming the pump is working ok and fluid isn’t spraying on the ground under pressure then it’s going sight-seeing inside the system somewhere.

 

Check your hydraulic fluid level. When you Chek it male sure all cylinders are retracted when you check the level.

 

Just taking a hose off and saying there's pressure there is meaningless. Unless you put a gauge in that circuit and have a spec to compare it to you can't draw any conclusions yet.

 

Are hoses on correct.