Need advice on brake system

[Primrose Captain]

At my Volunteer Fire Department we currently have a deuce that keeps having catostrophic brake failure. The department has either rebuilt or replace the master cylinder several times and the brakes still keep going out. As the Captain of the department I was enroute to a brush fire when the brakes failed the last time. Can anybody please tell me what can be causing this issue and what might be a fair price to post this truck forsale because we are considering selling it since we now have a 1993 model deuce. The truck in question is a late 60's early 70's model kaiser we also have another older kaiser that the transmission is bad that we are considering selling. If anyone can please help me figure this out I will greatly appreciate it because any monies we get for these trucks will go towards geting us more equipment and keeping our other 2 deuces on the road. We also have a tow bar we are looking to get rid of.
Thank you

 

[GHall]

What kind of brake fluid have you been using? Dot 3 or Dot 5?

 

[DeucesWild11]

Did anyone consider the other parts of the brake system? Airpack? Wheel Cylinders?

 

[porkysplace]

As far as selling you could list in the classifieds here ( you need to upgrade to premium membership click on upgrade on the top toolbar , costs $15 a year ) or try craigslist or e-bay .

 

[197thhhc]

I would have to lean towards contaminated brake fluid also. You can't mix DOT3 and DOT5 which is what the deuces come with.
If you have had mixing you will need to go through all brake parts.

 

[clinto]

So only the master fails? And you're testing it each time to see if it is the failed component?

No leakage otherwise?

I assume the failing aspect is loss of pressure output?

 

[swbradley1]

Define catastrophic please as it pertains to your failure.

If you lost all pedal I would think you could put a power bleeder on it and immediately find a leak.

(Not in any order)
Airpak rebuilt or changed?
MC rebuilt or changed?
All wheel cylinders rebuilt or changed?
All lines good?
Using DOT5 or DOT3 only after lines flushed?
Brake linings okay?
Brakes on each wheel adjusted properly?
Bleed lines properly starting at airpak?

Single circuit system is a simple system if you go through it correctly.

 

[frank8003]

Is the master cylinder vent open to the axle vents or open at all or has been squished over?

 

[Heavysteven]

I made some video on the M35A2 brake system. Here is one on the airpack.http://youtu.be/-q74Hkk0m4g

 

[73m819]

Define catastrophic please as it pertains to your failure.

If you lost all pedal I would think you could put a power bleeder on it and immediately find a leak.

(Not in any order)
Airpak rebuilt or changed?
MC rebuilt or changed?
All wheel cylinders rebuilt or changed?
All lines good?
Using DOT5 or DOT3 only after lines flushed?
Brake linings okay?
Brakes on each wheel adjusted properly?
Bleed lines properly starting at airpak?

Single circuit system is a simple system if you go through it correctly.

start at M/C then airpack, then on to the rest of the system

 

[Primrose Captain]

Thanks for the suggestions every one I will get with some of my guys and check into the rest of the system. As far as my meaning for catostrophic failure when I went to go out the bays on a call and the truck kept going even though I was standing on the brake pedal it went right out into the middle of the highway.

 

[clinto]

Thanks for the suggestions every one I will get with some of my guys and check into the rest of the system. As far as my meaning for catostrophic failure when I went to go out the bays on a call and the truck kept going even though I was standing on the brake pedal it went right out into the middle of the highway.

Oh-the pedal was rock hard but the truck didn't stop?

That's 99% likely not to be a master cylinder issue. That's airpack.

 

[m-35tom]

and this was after you let the air pressure build up? with a bad airpack, you will still have brakes, just no assist so hard to push.(unless the hyd piston in the airpack is rusted in place) the brake system is very simple, it sounds like your entire system should be checked and the offending parts replaced.

 

[Robc]

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