no brakes on JD 300 industrial

[lowufo]

I have no brakes on my machine. Drained and changed all hydo. fluid and filters. was real ugly grey fluid. put new boots on shift levers.and now keep in the barn out of weather. Tried bleeding them several times. no luck. last time I bled them the fluid was looking milky again after only 20-30 hours of use. ???. any sugestions ??
Thanks

 

[beenthere]

:welcome: to the forum.
Sounds like water contamination. Somehow need to clear up the hyd. oil, but have no good idea how.

What more can you tell us about the 300. Age? model (loader, backhoe)? Brakes are in oil, right?

When you say "bleed" them, do you have a master cylinder? Are the brake pedals spongy, or what does bleeding do?

 

[Tx Jim]

No brakes could be caused from valves in master cylinder not seating or leaking o-ring on brake pistons in one or both final drives.

 

[lowufo]

:welcome: to the forum.
Sounds like water contamination. Somehow need to clear up the hyd. oil, but have no good idea how.

What more can you tell us about the 300. Age? model (loader, backhoe)? Brakes are in oil, right?

When you say "bleed" them, do you have a master cylinder? Are the brake pedals spongy, or what does bleeding do?

I know no additional water contamination has accured. It's been stored inside.I would guess that the milky looking fluid is what has been circulated around the system from not being able to drain every last drop out. Is the a way to get every drop of old fluid out ? when I first bled the brakes after new fluid and filters it still had nasty old fluid coming out and could not get the new fluid to come oue ,even after a number of attempts. Machine is a 60's era tractor,backhoe is a 92 model. loader ?original equipment. I have a master cylinder but never touhed it,only the bleeders on the axel.NO pedal.no air coming out the bleeders.I do have brakes at the very top of the pedal stroke on ocation. but it is only at one point in the pedal travel near the top. any movment past that point is no resistance at all on the pedal and no brakes. if i depress the pedal quickly there is nothing at all. going very slowly I can sometimes get a little braking action at the very top of the stroke the nothing
Thanks
Mike

 

[beenthere]

From the sounds of it, then a decision needs to be made to either continue with the contaminated fluid, or drain and replace again. Not sure if keeping it is a gamble or not.

Next choice seems to be to isolate the master cylinder as a problem. Find a way to test each brake to check the o-rings as TXJim suggests. Maybe a pressure test on the output side of the master cylinder would point to the problem. Maybe at the bleeders on the axle that you mentioned.

Just some thoughts, and others may have better suggestions.

If ok, then going further to the brakes to find the problem will be necessary.

 

[sailfast]

Keep at the bleeding until the fluid improves, may take some time. you may want to change the hydro again to clear up the remaining water. after the bleeding improves the fluid watch for more air.

If no more air turns up after the fluid improves then look into rebuilding the master.

You have to get past all the old fluid to be certain to clear the air from the fluid change and you really dont want that water in your brakes.

 

[buickanddeere]

Remove the return line from the loader and don't let it drain back to the trans sump.operate all functions until oil returns clean. Repeat with backhoe.

 

[Tx Jim]

lowufo
Here's the part number for the kits to overhaul the brake master cylinder.
KIT AT182633 BRAKE VALVE OVERHAUL (REQUIRES 2 KITS FOR 1 VALVE)

 

[Gale Hawkins]

Remove the return line from the loader and don't let it drain back to the trans sump.operate all functions until oil returns clean. Repeat with backhoe.

Make sure you have 25 gallons of new fluid on had to complete this process if you are going to go for clear clean returns. :thumbsup:

The water does not have to come from rain. There is some in every cylinder that forms/gets trapped and with use will get back to the transmission sump I just learned with our JD 310. I drained the transmission three times over a period of one week and got clear water out each time when I first pulled the plug.

Using a few cans of Sea Foam helped. I replace the filters twice and dropped the filter four times. After adding back a total of 20 gallons of fluid it was quite clear the last time I used it.

It is my guess 70% of old equipment has water in the fluid to some degree.

 

[megaboz]

Get some good hydraulic fluid that won't blend with the water. It will take a while to get the water out with cheap oil. Eventually you will dilute the water enough. But it will take a while. Most cheaper fluids like OEM fluids will just mix with water.