need advice on changing hydraulic filter on 1845

[ernemats]

I just changed the hydraulic filter on my 1845 and was in the process of bleeding the system.
The bleed port is on the top with a tee, I connected the bleed hose to one side of the tee and cranked the engine and hydraulic fluid came out at first then just a little then none. I have tried several times after that and no fluid is coming out now. The hydraulic filter is full of oil and the tank is at the full level, any advice?

 

[J_J]

Bleeding the hyd pump should have been fairly easy as most of us have done it many times. Did you fill the oil filter up before installing?

What I think happens is this. The charge pump will try and charge up the VSP, and until it picks up prime, it is pumping air. The process we go through is to remove that air so as not to get any air in the hyd motors or pump. If you do not get all the air out of a closed loop system, it could cavitate and stall or destroy some parts.

On my Case skid-steer, which is also a closed loop hyd system, they also loosen the motor hoses and crank the engine until the charge pump gage reads 50 psi. After all air is out, they tighten the motor hoses and run the motors at full speed and see if the charge pump reads about 400 to 500 psi and everything works correctly.

 

[ernemats]

I have done this on my 422 many times but this is only the 2nd or third time on the 1845. I never had any problem before. I did fill the hydraulic filter to the very top of the filter. I filled it then waited for a while then refilled it to the top several times until the oil would not go down any.

 

[ernemats]

Just a follow up I talked to Terry today and his suggestion was to use the air compressor to pump air into the hydraulic oil tank while cranking the engine and it worked.

 

[woodlandfarms]

Never heard of that one before....

 

[J_J]

Normally a gear pump will pick up and prime itself, especially if the pump and tank it is at about the same level. The air forces the fluid up hill to the charge pump.

 

[BobRip]

Would it be good to do this on the 422/425 series? You could force all of the air out without putting wear on the pumps.

 

[J_J]

There is no reason not to if the charge pump will not pick up the fluid. It is just an assist.