Volvo Ec 15B - Hydraulic behaviour

[wowe]

Hello,

I noticed the following behaviour: The motor runs normal and if the joysticks are in neutral position - the boom holds it's raised position. Then I pull only some millimeters the joystick for lifting the boom - and the boom SINKS slowly and the motor sounds as in neutral position. If if pull the joystick further a few millimeters, the boom is rising and the motor sounds that he must work. It seems as at the hyraulic valve the flowback path is opening before the pressure path. This behaviour is only existung ath the boom hydraulic.
I think it's nothing for repair.

Regards wowe

[Mattir]

Have not noticed or at least paid attention to such micromovements. Which type of work do you mostly do with your 15?

[Muz]

ON some machines (not all) I seem to remember this behaviour 'can' be consistent with seal failure, or seal pack separation in the boom lift ram. The test for seal failure that has been documented elsewhere in the forum and is simple enough whereby you rest the bucket on a post or something, then connect the inlet to the outlet, knock away the post and see if the ram drops ... if it drops then something in the seal pack has failed .. separation would be evident if the machine cannot jack its self up . Interestingly .. if neither of those apply .. what action do you see when the ram is pressurised the other way when you jack the machine up ?

[wowe]

what action do you see when the ram is pressurised the other way when you jack the machine up ?

This works without this effect. There is no moving down, before the digger moves up.