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Curtis B.
Curtis B., Technician
Category: Industrial Equipment
Satisfied Customers: 32351
Experience:  Technican turned service manager on multiple lines of equipment used in industry.
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I am using a Bil-Jax 3355A. The upper boom is drifting down.

Customer Question

Hi. I am using a Bil-Jax 3355A. The upper boom is drifting down. Also, whenever another function is being used, such as the outriggers, as soon as there is pressure on the system (such as when leveling machine up with outriggers) the upper boom will go up. It doesn't stay up though. As soon as control buttons are released it begins to drift down until it is back to the stowed position. I am guessing one of the O-rings are bad in the valve controlling that upper boom, thus allowing pressure to escape as well as back pressure from other functions to enter and pressure up the system. I just don't know which valve controls that function.
JA: What is the complete model and serial number of your machine?
Customer: Model: 5533A
JA: Anything else you want the industrial mechanic to know before I connect you?
Customer: Serial: 55A07-00070
Submitted: 1 year ago.
Category: Industrial Equipment
Expert:  Curtis B. replied 1 year ago.

Hello! Let's see if we can can work together to get to the root of your question!

Expert:  Curtis B. replied 1 year ago.

See the hydraulic hose routing, and the valve associated to it. See link below. You may have cylinder with internal seal leaking!

Customer: replied 1 year ago.
I don't understand if I have a cylinder with internal leaking, why would that boom be going up even when I'm using another function like the stabilizers which are unrelated? The lower boom is on the same hydraulic circuit, so that I could understand, but not an unrelated circuit I wouldn't think. It seems it must be getting pressure through the valve body somehow. Is it possible that the valve on my cylinder is also bad? Perhaps there are two issues, it's getting back pressure through the valve body and the valve on the cylinder itself is bad allowing it to pressure up that side. I've never had one of these cylinders apart, so correct me of I'm wrong, but I'm assuming there is a valve at the base of the cylinder that is operated electronically based on selected function? Since the lower and upper booms are serviced by the same hydraulic lines, there must be a valve on each cylinder.
Expert:  Curtis B. replied 1 year ago.

It does seem like there is more than one probelm, and yes, it can be related to the solenoid valve that controls the lift cylinder. If it does not seat, it can get pressure from another function, and it could also cause cylinder to drop. Pull the solenoid valve with the boom in the stowed position, and pressures released, engine off and look for obvious damage or o'ring blown.