2155 brake bleed problem

[Jim.ME]

I believe that flexible line is a drain back to the transmission case once the reservoir fills and would be the same off the brake valve since it should be fed by the high pressure pump after the steering but I’ll double check that in the morning.

there should be a brake line off each side of the valve that heads to each brake. Then is there a 4th line? Or is that it? It’s possible that it could connect to the case and get fluid from an internal line but I thought it was external.

It appears to be fed some by the excess flow line. That excess fluid line is where the reservoir plug is in some of the earlier ones.

If it is getting fed from the oil cooler return as some are, I believe it is internal. Without the right flow drawings and info in TM4436 this is speculation.

 

[GR Gold]

As Fixingfarmer posted, TM4436 is the manual you need to get system descriptions, schematics, flow diagrams, specs. and testing. TM4435 is the manual for "wrenching" to make the repairs, not for troubleshooting and diagnosis. TM4435 will only tell you how to rebuild the brake valve and how to bleed the brakes.

Please clarify. In your first post you posted you cracked the brake bleeder a bit and cycled the pedal several times and basically only got spurts of air. Did you actually open the bleeder and cycle the pedal up and down several cycles with the bleeder open (as I read your posting). Or did you push and hold the pedal down, open the bleeder to allow air/fluid to escape, close the bleeder tight and let the pedal up. Repeating those steps each time?

Have you checked for fluid in the brake valve reservoir as I suggested?

I marked up the drawing you posted to show where the oil is supposed to be going in each line. The front reservoir should have something in the bottom between it and the main pump. The fluid can flow both ways in that tube/hose as needed. If the main pump is not getting oil from the transmission pump the oil flows into the pump. When the main pump is receiving more oil than needed the excess flows up to the reservoir with any excess going to the brakes and transmission. If that front reservoir tank is not getting oil enough to send oil back to the brakes and transmission the brake reservoir isn't going to fill.

I wonder if something is plumbed wrong or a small part got lost during the front-end repairs you did.

View attachment 164093

My first attempt at bleeding I did just as the owners manual suggested. Put a clear tube over the left bleed screw and submerged the other end in the bottom of the rear end down from the fill cap. I then opened the bleed screw about a quarter turn and left it open, and cycled the pedal for what seemed like an hour. I could see occasional spurts of fluid going down into the rear end. After no luck that way, I got my son to cycle the pedal up and down as I opened and closed the bleeder, like how I would do a brake bleed on a car. This was all done with the engine up around 2100 rpm. I feel confident everything is plumbed right as I have another 2155 sitting right next to it to compare to. I thought the same thing that the line from the top of the tranny was a vent, and not a supply source. Unless it is fed from a passage between the brake valves and the trans housing, it would have to come from the reservoir in front of the radiator. I am not getting any fluid from that line. I suspect that the reservoir has not filled yet, but I don’t know why. I replaced all the hosed between oil cooler, reservoir and pump so I know all that drained out. Tractor has one set of remotes, and I rigged up a jumper hose between the two, thinking I could purge any air out of the hydraulic system that way? I had to put up for the night but will get back on it tomorrow. My best idea for getting fluid down the tube into the brake valves is a large syringe, and I will try that tomorrow as well. I will report back, and thank you!

 

[Jim.ME]

As is often the case, many theories come up. My view is the line in question is nothing but a vent line. Both the supply and actual return (or overflow) ports are on the tractor side of the valve and not visible unless the valve is removed.

I do not disagree, the correct manual with the drawings and description would be beneficial. If that line is excess flow from the front reservoir and tee'd into the return line to the transmission cover, it would seem it would have fluid in it most of the time.

 

[Harry in Ky]

It would "seem" so, but my limited experience shows it really doesn't.