Old kubota kh66

[Mark lanark]

Hi folks, I have owned an old kubota kh66 2.8t digger for past couple of months, I had the dipper ram fail and I replaced and had the machine working for a couple of hours, I then replaced the hydraulic oil as the tank was very low, drained it out the tank, cleaned out tank then re filled the tank and now when I start up I have no hydraulics working. 
I took the hose off to dipper ram and then I operate that, the fluid does come though but next to no pressure, also when I go to work the joysticks there’s no dip in revs or noise like it normally does like under load as it would be when normally operating. I’ve cracked the 3 nuts (bleed valves I assume) on top of the pump an there is fluid running out when engine switched off. Any ideas of anything I’ve missed or should be doing.

first time owner of plant so learning as I go. Many thanks, mark 

[Johny Walker]

Could be an air lock

[spuddog0507]

Did you change the filter as well when you changed the oil ??

[dig-dug-dan]

24 minutes ago, Mark lanark said:

Hi folks, I have owned an old kubota kh66 2.8t digger for past couple of months, I had the dipper ram fail and I replaced and had the machine working for a couple of hours, I then replaced the hydraulic oil as the tank was very low, drained it out the tank, cleaned out tank then re filled the tank and now when I start up I have no hydraulics working. 
I took the hose off to dipper ram and then I operate that, the fluid does come though but next to no pressure, also when I go to work the joysticks there’s no dip in revs or noise like it normally does like under load as it would be when normally operating. I’ve cracked the 3 nuts (bleed valves I assume) on top of the pump an there is fluid running out when engine switched off. Any ideas of anything I’ve missed or should be doing.

first time owner of plant so learning as I go. Many thanks,

Not sure if it helps, but when I fill up my crushers, I undo a breather first to allow all the oil in. If I dont, I cannot fill it up without an air lock

Did you measure how much you put in compared to what should be in the system?

[Mark lanark]

Thanks for the replies, the machines capacity for oil is 65ltr and I’ve put in just over that, still a couple of inches or so from top of tank. 
I didn’t change filters (I know it sounds mad) but I was under pressure to have machine back on the road and I couldn’t get a filter for a few days, thought I’d just change oil and get it back working and do a full service later when machines not needed as much. 
if it is an air lock what’s the best bet to clear? Remove hose at each ram and run through? 
the fact that I’m getting no noise change when using joy sticks I was wondering if it was something more serious like pressure relief valve jot sending fluid to the rams and just circulating it . Again.. I don’t know much so might be talking rubbish. Cheers