Brake Pedal goes to floor after LONG Warm up

[JLinOK]

John Deere 5310 circa 1999. Just replaced the hydraulic control on the brakes (the old one blew out). My brakes work fine until I run my max size shredder (MX-7) for about 3 hours, then they get soft and eventually go to the floor with no breaking at all (this has happened multiple times). Today I worked on dirt moving and road work for 3 1/2 hours and had no problem. Any thoughts before I mortgage my house and go talk to John Deere service (kidding, a little)?

 

[rScotty]

Wonderful tractors. Almost bought one myself.
If the hydraulics brakes on the 5310 run on the same fluid that the rest of that open center tractor hydraulic system uses, it could be heat or a suction air leak in the line from the sump to the hydraulic pump. Those and a clogged cleanable sump filter are the two or three most common causes of hydraulic problems in open center hydraulics. If the loader is working at full cyce speed it's not the sump filter.

You can check for heat or entrained air by pulling a sample of the hot oil for smell and then look to see if it is cloudy. If it is too hot, the oil may be ruined. In that case, clean the hydraulic fluid radiator fins and generally check it with a heat gun. Replace the oil with new.
If what you see is cloudy oil and you suspect suction air is being entrained into the fluid, put a few ounces of hot cloudy oil into a jar and let it set overnight to see if it clears up. Replace the suction hose just for drill.

If the brakes controller fluid is independent of the tractor hydraulics and has its own pump and reservoir just for the brakes.... well, them I don't have any ideas except that the friction plates/shoes may be set up too tight.
good luck,
rScotty

 

[JLinOK]

I am wondering what about running the PTO at 2500 rpm for 3 hours would affect the brakes. I believe the tractor hydraulics control the brakes as well. However, as you ask, the loader does not seem to be affected. I know heavy use of the loader for the same period of time does not seem to have an effect on the brakes. When they go, they go from one inch of travel to engage the brakes to 'to the floor' travel and no braking. I am going to go into JD, I just wanted to maybe get some inkling of what is going on beforehand.

 

[rScotty]

JLin, at this point I would need to look at some diagrams of the 5310 hydraulic system. If you can link me to them or provide them I'm willing to take a look.
rScotty

 

[Tx Jim]

Have you tried bleeding brakes? If so my guess is check valves inside brake housing aren't seating properly. My understanding of brake valve operation is hyd system is only utilized to keep brake valve reservoir full of hyd oil but supplies no direct hyd pressure to brake linings. Note hoses attached to brake valve with clamps.

 

[JCMartin]

Any update on this? My 5310 from 2000 has started doing the same thing. Usually pumping the brakes a few times seems to build braking pressure again and I can stop. Only does it when hot after running for a good while. I am suspecting hydraulic filter and fluid change is needed (overdue). Seems to make the steering a little choppy too.

 

[Dave M7040]

I have a WSM for a similar model. It has an excellent description on how the tractor's hydraulic system feeds a more traditional brake valve. You machine may be similar in design but I am guessing on this.
I hope you find the info helpful.
Dave M7040

 

[JLinOK]

Just updating. I have not brushhogged/shredded/etc. for several hours in the heat for a while. The problem has no recurred so I haven't investigated further. I have run the tractor for 3 hours of front end loader work and no problems. There is not much else for me to say. JD dealer said bring it in and they would check it but I don't want to do that unless I know I can repeat the problem. Sigh.

 

[LouNY]

My guess would be that several hours of working the tractor hard brush hogging got the hydraulic fluid warmed up real good and you have a small leak that is only apparent when the oil is hot it could be in either wheel piston seal or possibly in the equalizer in the master cylinders.
Several hours of brush hogging would quite likely get all the fluids much hotter then a few hours using the loader.

 

[JLinOK]

My guess would be that several hours of working the tractor hard brush hogging got the hydraulic fluid warmed up real good and you have a small leak that is only apparent when the oil is hot it could be in either wheel piston seal or possibly in the equalizer in the master cylinders.
Several hours of brush hogging would quite likely get all the fluids much hotter then a few hours using the loader.

Thanks, that is somewhat what I thought. Now it is cooler and I am not brush hogging I have not had a problem. Next year when I might have to fix it, I will know.

Any update on this? My 5310 from 2000 has started doing the same thing. Usually pumping the brakes a few times seems to build braking pressure again and I can stop. Only does it when hot after running for a good while. I am suspecting hydraulic filter and fluid change is needed (overdue). Seems to make the steering a little choppy too.

I have quit having the problem, but I think it is because I am not getting the fluid as hot...cooler weather & less brush hogging. I suspect it will come back next year. This being an identical machine means something.