Hydraulic self bleeding?

[wateka]

I've read multiple threads here that note Bobcats are self bleeding. My service manual does not address the subject. What it does say is that the hydraulic reservoir is almost 4 gallons and the hydraulic/hydrostatic system takes 8 gallons.

I am refilling all the fluids in my 853 after a complete disassembly and the hydraulic fluid reservoir is full but I've only put 5 gallons in.

Do I really have 7 gallons of burping coming up?

Since only 1 gallon has drained to the hydraulic/hydrostatic system, I'm worried about burning something up before it burps itself.

It's late enough now so that it'll sit overnight before I start it up, but holler if I'm missing anything.

 

[FJRDarksider]

You probably thought of this but perhaps running it for short spurts (5 sec) a few times to allow fluid to circulate and top up the reservoir........and then the same for operating the hydraulics? I would be nervous too given the complete tear down you did. Maybe the relief valve to allow freewheeling might assist in purging air? I'm speculating of course.....

 

[Tazza]

When i did my machines, i had a fully empty system, as in pups, lines and cylinders, not just a strip down, it was a re-seal and rebuild of pumps, there was only assembly oil on all components. I had the same issue go through my head.

My way around, no idea if it helped or not, but i put fluid in the tank then got someone to sit in the cab and operate the hydraulics while i pulled the ram sticks out, this pulled fluid through the pumps and into the lines and cylinders. After that, i started the machine and then over time, it bled all the air out of the system, no issues at all.

 

[wateka]

All good thoughts, thanks.

Tazza - I've got the same scenario as yours - every square inch (or for you, cubic cm) of the hydraulic/hydrostatic system has been taken apart and cleaned/restored/replaced and all the hoses are new. So, other than assembly oil, there's nary a drop of hydraulic fluid in there, until last night's refill. I'll try lifting/lowering the arms with my gantry/chain hoist and put my iPhone on the reservoir tank fill port to video whether any bubbles materialize.

FJRDarksider - I did think of the relief valve idea, but I've got new chains and bearings, so it was very hard to turn (granted, with the wheels off) even before I reattached the hydraulic system, so I didn't try that. The Isuzu engine has also just been overhauled, so I have to weigh those overhaul startup procedures as well, relative to the start/stop.

Sun's coming up - we'll see what happens.

 

[wateka]

Well, the Isuzu fired up after 12 long seconds of cranking and seems to be doing just fine. As for the bleeding, it's STILL not finished, and I've had the engine running (although not at max rpm) for about an hour. I can get the lift and tilt functioning, but no movement at all with the wheels.

Look like this in the reservoir tank:



I've stopped for the night and will see if gravity does anything over night.

 

[FJRDarksider]

Can you post some pics of the finished unit? Would love to see what my 853 "could" look like LOL.

 

[wateka]

Can you post some pics of the finished unit? Would love to see what my 853 "could" look like LOL.

Will do, but after Thanksgiving. I haven't put stickers or rear door back on yet.

 

[wateka]

@Tazza - this comment, from 2015, let me quit worrying about how long the priming process was taking. Once again, the knowledge base here in SSF is tremendous.

Post in thread 'Bobcat 310 hydraulic bleeding?'
https://www.skidsteerforum.com/threads/bobcat-310-hydraulic-bleeding.88781/post-88793

"It takes time for all the air to bleed out, don't expect it to go in one day, if there is a lot, it can take a few days to settle down.

Jittery and noisy hydraulics is normal for a while after a repair like this."