Hitachi EX60 - Hydraulic Leak - Slew Motor or Centre Joint

[DRC65]

I'm hoping from some guidance about the best way to identify where my leak is coming from

It's an EX60-1 and I noticed oil spilling out of the ring gear. Pretty certain it's hydraulic and the level of hydraulic oil has dropped. There's no oil on the top side of the structure around the swing motor or centre joint and none of the pipes appear to be leaking. Swing motor gearbox oil level appears correct (although thinner oil than I expected).

I slid underneath and there is a coating of oil over the bottom of the centre joint. I took the small plate off the bottom of the undercarriage that accesses the void inside the slew ring and drained out about 5 litres of water (!) followed by 10 litres of hydraulic oil. Once empty I could see up inside with a mirror but no obvious sources of the leak.

When the engine is running there is a steady trickle of hydraulic oil from this opening but I can't see where it's coming from. Everything operates correctly but there's no change in the rate of oil leaking when I use any of the hydraulic circuits (incl slew, blade or tracks).

Any guidance that you can suggest to help point me in the right direction would be much appreciated.

 

[Tones]

Reckon it's the centre joint. If it was the slew motor then the slew gearbox would be chocker block full with hydraulic oil.

 

[DRC65]

Thanks for the quick response. You got me thinking about the slew gearbox so I've been having a look tonight and realised that what I thought was the mark on the dipstick is a scratch and and the level is double the height up the dipstick that it should be ie about 1 1/2 in. But whilst it's clearly overdue for a change it's definitely thicker than hydraulic oil and smells like gear oil ( I hate that smell :dizzy ). Running up the machine and leaving it idling for a while and the level doesn't change.

Now I just need to decide whether to change the slew gearbox oil and get it to the right level and then see if it changes....or just bite the bullet and drop the centre joint out

I guess if I supported the centre joint and loosened off the bolts holding it to the undercarriage chassis and dropped it an inch (if the pipes allow) I'd be able to see for certain if it's the culprit ?

 

[DRC65]

In case it helps anyone. I never tried dropping it to see if it was leaking - there's limited movement with rigid hydraulic pipes.

It was however the centre joint (an HCJ-080A). With a split in the top seal (see photo).

Now to try and trace a seal kit but the local main dealer seem to be finding this (apparently simple task) difficult!

 

[mikebramel]

Measure the OD of the center of the joint, then measure the Oring cross section