brake issue reo m275

[johan77]

hi guys,
update on the m275 tractor brakes...airpack rebuild, master cylinder rebuild (this one was in fairly good shape). I connected everything back in place, filled the master cylinder with the proper brake fluid, than i bled the airpack first (without having air pressure), after that i run the engine untill air presssure was build up. (little above 90psi) and started bleeding on the wheels with the help of an assistant. (the airpack i did myself since it was easy to pull on the brake pedal from underneath the truck.)

good thing is that now when there is air pressure the truck is still rolling, the brakes are not applied, BUT i have no brakes at all, i can push the pedal to the floor with very little or no resistance, when released the pedal is also coming back to its position faster than the piston in the m/c.

Is there still air inside somewhere ? with the engine off, air pressure at 90psi and pressing the pedal you can hear a surging sound from underneath, i think in the airpack (the piston rod inside the airpack is moving because the large spring is making some noise).
the pedal is not spongy , you can go all the way to the floor...
help......

 

[cattlerepairman]

Sounds like there is still air trapped in the system, if you do not have any fluid leaking. My suspicion would be in the air pack. You can definitely bleed the brakes as you describe, but I find using a power bleeder is much more likely to be successful with 1 (-2) rounds of bleeding. You probably need to let the truck sit a bit and then re-bleed, probably a few times. Also, are your brakes adjusted correctly? 12 brake shoes way out of adjustment can use up a lot of wheel cylinder travel.

 

[johan77]

can the system be bled without having air pressure in the tanks/air system ? the shoes should be fine because before rebuilding the brake system (airpack was totally messed up inside and air passed trough, applying the brakes without touching the pedal, it was also impossible to press the brake pedal even a bit) and the truck didn't move even half a inch.....but maybe worth to check...i will go first with some more bleeding,

you think air trapped in the hydraulic side of the airpack ? i bled the airpack also using the brake pedal, but i've read somewhere about gravity bleeding the airpack, open the valve on top of the airpack and wait until fluid runs out ….??

 

[johan77]

brake shoes are moving towards the drums, (checked trough the inspection holes in the drums where i was able to reach) and rectracting again when releasing the pedal. (no air in the system) looking on the inside of the drums also no wet or strange spots from any leakage) with the cap off the master cylinder and pumping the pedal you can clearly see the the fluid coming back into the M/C, not like a fountain when releasing the pedal slowly, the fluid level is also staying the same, however, once and a while when releasing the pedal there are bubbles of air coming out of the bottom of the M/C, maybe one time in 15 times pumping.....how long does it take to bleed the far most wheel on the truck to be sure there's no more air in it ? can it be that something inside the airpack is not working properly ?

according to me if there should be an internal leak (or any leak ) in the airpack the fluid level in the m/c should drop or at least go less and less…? it does pushes the fluid around but it seems not to build up force enough to make the brakes do their work...if there is air inside the system, the pedal should feel spongy right ? this one does not, it can 'easily' pushed to the floor

 

[Katahdin]

Try bleeding your air pack one more time after all the wheels have been bled. I've noticed improvements in pedal travel just by bleeding that.

That said, I am also a fan of pressure bleeding. Veterans told me they had trouble bleeding brakes by pumping the brake pedal because it would introduce air bubbles into the system. I've always used a pressure bleeder and never had a problem. The air tanks do not need pressure when bleeding the brakes.

My pressure bleeder (pictured) is a 1 gallon weed sprayer that connects to the MC cap with a quick-connect air tool fitting.


All 3 of my deuces have the same fitting so I can quickly bleed or top off the brake fluid in either one of them.
More details on pressure bleeding here:https://www.steelsoldiers.com/showthread.php?3229-Deuce-Power-Bleeder-R4x4-Style

When pressure bleeding follow the same steps, start with the air pack first then move to the rear-most-passenger side wheel, and so on.. I don't bleed an extensive amount of time at the rear-most wheel, just enough to see clear fluid without bubbles.

 

[johan77]

UPDATE !!!!!!! we have brakes !!!! and what a stopping power the little m275 has, she suprised me, ….and i slided forward barely was able to hold myself from hitting the windshield

Thank you guys for all the tips and info !! all it took was patience, some gentle touching, 2 liters of brake fluid and bleeding the system some more, , for now, no leaks detected, next issue will be the emergency break (nothing of the items is on the truck) or the front driveshaft universal joint....

i installed also a water / oil trap (like one on the small Household portable compressor) just behind the air compressor to catch some moisture but i'm not sure it that will be the right place, maybe better place one just before and one just behind the air tanks ?? as close to the 'users' ….

Me happy !!

 

[rustystud]

UPDATE !!!!!!! we have brakes !!!! and what a stopping power the little m275 has, she suprised me, ….and i slided forward barely was able to hold myself from hitting the windshield

Thank you guys for all the tips and info !! all it took was patience, some gentle touching, 2 liters of brake fluid and bleeding the system some more, , for now, no leaks detected, next issue will be the emergency break (nothing of the items is on the truck) or the front driveshaft universal joint....

i installed also a water / oil trap (like one on the small Household portable compressor) just behind the air compressor to catch some moisture but i'm not sure it that will be the right place, maybe better place one just before and one just behind the air tanks ?? as close to the 'users' ….

Me happy !!

The deuce's brake system when properly maintained is a real stopper ! Yes drum brakes can be a pain in the butt sometimes, but it will stop your truck !
To bad they never made an "air" brake system for the deuce though. That would have been real handy.