Just changed hydraulic oil and now have no hydraulics

[apring]

Everything was fine till I changed hydraulic oil and filters now have no hydraulics. The tractor, M4800 goes back and forth OK but no 3 Pt lift and no loader action. New oil is 10.5 Gals UDT super as called for by manual. Any ideas?

Thanks for your help

Andy

 

[Paystar]

The service manual for my B says if it gets an air lock like that, just turn the steering lock to lock several times. Maybe try that?

 

[CHDinCT]

Agree with Paystar - sounds like air in the system that needs to be purged.

 

[apring]

The service manual for my B says if it gets an air lock like that, just turn the steering lock to lock several times. Maybe try that?

When I tried to turn steering wheel I couldn't. I jacked up front end and after turning back and forth for a while the steering works good so I am sure you are right - it has to be air. Still no loader, 3 Pt lift and no PTO. Anyone know how to purge the entire system?
Thanks very much for your help guys.
Andy

 

[meos1]

Bleeder valve somewhere perhaps?

 

[wolftree]

Try cracking open/loose a hydraulic line going to the steering hydraulic cylinder, then turning the steering wheel back and forth to purge the system of air.

 

[JoeL4330]

OP: no PTO ?? not clear how an air bolus in hydro line causes that ...but, I don't have a 4800

 

[Garycw]

Not sure but I thought all hydraulic pumps have a blender valve. Check your service manual. There may be more than one point to bleed also.

 

[sandyc]

Bad filter? Think I would drop filter and see if there is fluid in it. If you break open a pressure line you really need to be careful you don't get hurt with the spray...**** of a nasty injury!
Make sure all connections are tight...I would disconnect and then reconnect all fittings to FEL.

 

[Stonehaller]

You may have a suction leak preventing the pump from priming. Check for a double gasket on the filter in case the old gasket was stuck on the flange and you did not notice it. If there is a rubber hose in the suction line, pinch it and look for cracks. Try loosening the hydraulic oil filler cap on the tractor housing in case the vent is plugged.

Tractors with open center hydraulic systems will not have an air bleed as they are not necessary. Any air in the system will get pushed out to the tractor housing (oil reservoir).