JD1520 loses brake pedal

[Darrownm]

When we bleed the brakes, they are disconnected from each other and bled individually.
Both sides are equally low and both are required to be bled.

Agree that air is getting into the hydraulic fluid somehow.

 

[Tx Jim]

As I previously stated I think the 1520 brake valve body & internal components is a little more complicated than an automotive type master cylinder. Trans pump supplies oil IE fills brake valve housing but in no way powers brakes with hyd pressure.

May I ask what you're referring to as the proportioning valve?

 

[Darrownm]

Notice that JD offers a brake valve overhaul kit (AR54929).....which is a bunch of O rings and a seal.
The brake valve on the tractor does not show any leaks, so not sure that would help. Any thoughts ?

 

[Tx Jim]

Having served over 13 yrs as as a JD dealer service manager my experience is that problems with JD utility tractor brake valve similar to 1520 was due to valves inside of housing that fail to seat properly or brake pedal height not adjusted correctly. This is presuming axle brake piston seals are good.

 

[Darrownm]

Thanks Jim for your input. Once we finish the mowing for this year, will work on rebuilding the brake valves on the tractor. Will report back what happens.
Thanks again.