The Power-Tracs have a variable speed hyd pump and has a bleed procedures when changing out filters or installation. It envolves filling the pump with fluid, and remove fuel to a diesel engine or pull a spark plug wire on gas engine so the engine does not run.
We use a tube connected to the bleed prifice in a container and motor the engine over until the air is purged.
Then tighten bleed screw and turn fuel on and start engine and let idle for a while,
You could then install gages and check some pressures in the pump like charge pressure and operating pressure.
Your system should be similar, look in the manual for your tractor for bleeding procedures.
Start-Up
On initial start-up, the case should be filled with oil,
pressure should be reduced and the circuit should be
open or the air bled from the pump outlet to permit
priming. Use of the airbleed is recommended on initial
start-up. See Installation and Mounting Section to
connect airbleed
A built in airbleed is standard on all PAVC 33, 38, 65
and 100 Pumps. To connect, remove airbleed drain
plug and connect a line unrestricted to reservoir
extending below minimum oil level. Back pressure
in this line must not exceed .28 bar (4 PSI).
Main point here is to remove all the air from the pump, and make sure the suction line is secure and tight.
