M103A3 - fluid leak around the brake chamber

[therooster2001]

OK, I've poured through the TM on this one. This is a M103A3, with an MKT sitting on top. The hand brakes do work to stop the trailer, but I have noticed some fluid only when the brakes are applied. Since I have not had soldier B to help, I have not been able to pump the brakes and notice what happens. I do have a bit of fluid coming off the airbrake chamber at the bottom and when I pull the trailer out and brake, it do see fluid on the ground. SO. I have a leak and I think it's the air chamber. Besides jacking the trailer and watching when soldier B pumps the brakes, what else can I check? The 5 ton muscles the trailer around, so it's hard to see if the brakes are actually working, except I do notice that my brakes take more air than they usually take without a trailer. Nothing locks up. The air does work, and I have hooked them up correctly (emergency and service). This is a recent rescue trailer from Ohio AFB that was trailered to me, so it's just settling in. I have not bled the brakes, nor checked the fluid yet to see how much leaked.

Is there another way to test this out? Has anyone had the airbrake chamber fail enough to leak fluid? Is there any replacements out there? Where can I find one? TM says 1 hour job.

 

[therooster2001]

bump for the smart peeps.

 

[jasonjc]

The part you are talking about is 2 parts. 1st is the air chamber , there is no brake fluid in it , but mite have oil from the air compressor.2nd part is a brake master cylinder. This could leak out the front and look like its coming from the air chamber where the two bolt together.

 

[therooster2001]

Thanks Jason, I do know about the two, but I'll do a more thorough inspection, but is it possible for the oil to come back to the air chamber from a "broken" gasket in the air chamber and leak? It looked pretty tight. Is there a seal where the two meet that might be broken? If this thing leaks (either part), is there a usual suspect? Unfortunately I don't recall too much of a leak, but it's been flung all over the axle when I was driving, so hard to spot. I guess I need to have soldier B to help. I saw both parts on the bay, do you know where I could source the air chamber?

 

[therooster2001]

A pict for those needing the visual. It doesn't seem that the air brake canister is serviceable, but the "boot", item 16 could be something that is causing the leak? And my airbrake canister looks a bit different, it has the clamp on it.

 

[jasonjc]

Item 16 is just a dust boot. The seal on the piston in the master cylinder is most likely the leak. If your air brake canister has the clamp it is the newer one, good thing. All it has inside is a spring and a rubber diaphragm and a flat plate with a rod. Air pushes against the diaphragm , the diaphragm push the rod out and into the master cylinder applying the brakes. If the diaphragm goes bad you can replace it easy. Any truck parts store will have it in stock. The older bolt together one is harder to come by. You can get a rebuild kit for the master cylinder.

 

[juanprado]

The booster is just a rubber diaphragm and spring. It rarely goes bad.

The master cyl is bad. The piston has o rings and cups. Some of those seals are bypassing and that is the fluid leak. The rubber cup on the end is just a dust boot to keep contaminants out but it does not function to seal the hydraulics.

I have a good used one if interested, send pm

 

[gimpyrobb]

I agree, sounds like the master cyl needs rebuilt. I doubt its the diaphragm.

 

[therooster2001]

Ok, it looks like it's definitely a removal to see what's wrong (after the brake check test) and most likely a rebuild in my future. I see Jason had a GREAT thread on the M105, which the M103A3 is similar and the TM doesn't specify anything that isn't the same (except for the M105A2C, which had the vacuum chamber I believe.)

http://www.steelsoldiers.com/showthread.php?61773-M105A2-brake-part-s

This rebuild kit is like $15, I think this will set me straight. The TM, of course, just says replace. Since i never had the pleasure of the master cylinder fun in a deuce like you guys, I get to tackle this one.

Thanks for all the help guys.

 

[rosco]

The brake fluid is probably DOT 5

 

[therooster2001]

So I found that the reservoir was completely empty, so that's why it wasn't leaking before. I filled it up, and sure enough the leak came out the bottom of the air canister when I hit the brakes, but as Jason mentioned probably out the gasket. I rebuilt the plunger and the plastic cap, but keep the rest. I put it all back together and refilled the reservoir, and aired up and hit the brakes, to no leak so far, but a cool noise I assume was just the air working thorough it. My questions:

Bleeding the brakes. The TM says to pump the brakes, which I'm used to on a car a long time ago, but is it the same on the air over hydraulic? Do you bleed the brakes while pumping them? I may have to do this alone, is this possible?

It also looks like each wheel has two points to bleed on each wheel. Should I bleed them all or just one? does it matter which point(s)?

I assume the tubing the TM describes is anything I can get at the parts store, right?

Sorry for the noob questions, but this is the first time doing it, and its the brakes, I want to do it right.

 

[Rmtaunton]

If your doing it alone make a brake bleeder out of a bug sprayer many many posts on how to do this on here

Good luck


Sent from my iPhone using Tapatalk

 

[therooster2001]

Link for those wondering about the sprayer.

http://www.steelsoldiers.com/showthread.php?3229-Deuce-Power-Bleeder-R4x4-Style

Looks like I have a buddy for tomorrow, anyone else on the manual process? All 4 bleed screws? Any order? Pump the brakes or slow push. The car method of pump, then hit the floor probably doesn't apply from air from the truck to the trailer...

 

[therooster2001]

Ok, it's all fixed. When I went to bleed, something was still off, and was leaking from the same spot, so I took it apart again. I found the issue. The washer in the end was jammed up against the outlet, bent in half. I replaced it with the new one, put it back together and painfully bled all four. I ran it out or really low once, so bled again. Got some good bubbles out of them, and changed from clear to purple (new civi dot5). I was using shop air, so had to keep airing and swapping the emergency, which was a pain. If I ever have to do this again, I'll go the sprayer route, but with the issue I had, I'm not sure I would have found the problem, as it was the pressure from the piston that was causing it to blow backwards after it couldn't release the pressure. Bored the wife, but we got it, so we can use it this weekend. NAPA also has two different labels for their branded Dot5, one actually has the MIL SPEC numbers, but the other one didn't. Same stuff.

I got stuck after I got confused at the order, and no thread on here has it. Jason's old post has the parts, just in mixed order. The cylinder order for repair parts (from front to back) goes like this:

Boot --> Retainer --> metal washer --> Plunger (seal to the front) --> Plastic cap --> brass cap for washer (usually attached to spring) --> Spring --> Silver filter-y looking thing with dome towards spring (flat end towards rubber washer) --> Rubber washer.

No picts, it was long enough tonight.

Question, is the best way to check the service brakes on the trailer would be to lift the trailer axle up so the tires can spin (again using shop air), then hit the brakes to see if it stops? Emergency would be the same or the hand brakes while slowly moving, right? Any other way to ensure that after the hydraulic issue that the shoes are engaging?