[dbart]

I work in a plant where we have several hydraulic systems. We always seem to be fighting hydraulic leaks. One system in particular we keep replacing o-rings between a valve with a DO5 pattern and the manifold block that it is sitting on with very limited success. Once we replace o-rings the leaks stop for a week or so then start dripping again. When we take the valves off to replace o-rings we often find the o-rings collapsed into the port. I am looking for suggestions to help solve this problem.
Thanks in advance.
David

[warrenb]

Get a bore scope and check out the valve internals.

[big iron]

When you have the spool out of the valve body check for bore damage, bore scope works great for this. if there is room a good light works fine .Also check the spool for any damage especially around the edge of the o ring grooves. Something that works great for older hydraulic valves and other related equipment that uses o-rings is to switch to quad rings, most hydraulics supply shops have them.
They have the same I.D/O.D sizes as regular O-rings the only difference is that O-rings have basically a single sealing face surface and quads have two.
Quad rings are used in many new hydraulic controls.
Hope this helps