Boom Cylinder leak down, new seals didn't work?

[sghpi1]

After re-sealing boom cylinder I have same problem of leak down. there is no check valve on the cylinder, only the two lines. The picture shows what I believe to be a plug on the high pressure side above the boom spool and a check valve above the swing spool. Does this sound correct and could the check valve even though it is above the swing spool be responsible for holding pressure in the boom cylinder? There is no diagram available of the control valve.
thanks

 

[Texasmark]

A check valve is a one way switch. If leaking it will allow the pressure applied to leak off. It consists of a ball, race, and spring. The ball or race can corrode and develop pits which leak

One of those valves may be a pressure relief valve. These valves are similar and can release pressure for the same reason, or in the case of the pressure relief valve especially as the spring ages it weakens and pops off at a lower pressure. Course if this were the problem you would know it when you tried to position your implement...it wouldn't lift as high or wouldn't lift the load you are accustomed to.

II don't see a control valve which you use to direct fluid where you want it. They are precision machined components with no gaskets to seal off pressure. Over time the metal to metal scuffing causes the dimensions to get sloppy and fluid can leak around them.

 

[kthompson]

Not knowing what the boom is on are you sure it has a check valve? First thing I would suggest is to verify that for my understanding is it may be depending on the valve to hold the load. I think you will find excavator's booms have check valve but not sure backhoe does. Know my fel does not have a check valve.

 

[nyone]

The one on the right is most likely the pressure relief.

You should beable to remove the top hose of the boom cylinder and not have it gush oil out constantly. Tou could also run the cylinder all the way one way to check the seals while having the other hose off. It will make a mess but tell you alot.

 

[oldnslo]

Is this on a back hoe?

Some companies have work port relief valves that also incorporate an anti-cavitational check valve. With out a schematic we are just guessing at what the items could be.

No one circuit should not the allow the other to leak down. The should be two separate circuits.