JD1520 loses brake pedal

[Darrownm]

Have a JD1520 bought used that we use for mowing. After bleeding brakes have both solid high pedals.
After a few hours of mowing, start to lose brake pedal height.
Pumping is then required to get a partial pedal.....
need to bleed brakes again to regain a good pedal.
Any thoughts or ideas on how to fix problem. Thanks in advance.

 

[Tx Jim]

Welcome yo TBN
Will pedals stay firm if pedals are depressed at same time? If so equalizer valve in brake valve housing is not seating properly.

 

[Darrownm]

Thanks for the reply.....pedals are always kept locked and depressed together

 

[Zebrafive]

Any external leaks? I somehow damaged the line to my left brake on my 2030 and had to replace it. I am thankful JD still had it available, prebent and at reasonable price.

 

[Darrownm]

No visible leaks, thanks.

 

[Roadworthy]

Somehow air is getting into your system or the hydraulic fluid is leaking ior bypassing nternally. This can happen in the wheel cylinders or the master cylinder. You can try unlatching the pedals to see if one stays good and the other needs bled. That can help localize the problem.

 

[radios1]

this can be caused by a master cylinder that is worn, I've seen this many times before..

 

[beenthere]

radios
Are you referring to the JD 1520 brake system? Are you familiar with the JD 1520 brake system? Same question of Roadworthy. Just curious...

 

[Tx Jim]

Ditto JD 1520 brake valve isn't very similar to automobile master cylinder

 

[radios1]

Ditto JD 1520 brake valve isn't very similar to automobile master cylinder

I'm not talking about the brake valve(proportioning valve). but that which is connected to the brake pedals, and develops hydraulic pressure using pistons inside the master cylinder, whatever it looks like, some form of it has to exist to build up the hydraulic pressure, unless it's just a valve that uses the hydraulic pump on the engine, but then, the engine would have to be running to engage the brakes, which is not a good idea at all!!..