M35a2 weird brake system issues

[GASCANS001]

I recently purchased a 1988 m35a2 deuce and once I got to the truck I needed to bleed the brakes. I flip the door up and found the mc. Now the weird part, it’s a plastic reservoir directly where the cast one should be. Added fluid began bleeding starting with the Mc and working from further to nearest. I flushed the entire system out of dot 3 back to dot5. I tried for 3 hours and never got any better (which I expected) sitting for some time. Next weird thing was fluid sound like it was bypassing inside the mc and definitely coming back into the reservoir. Is that normal? lines are in needing of some tlc. I plan to replace the entire brake system and rebuild my mc (if I can) and air pack (short style) In the near future. Trying to have brakes before hay season is over.

Where should I start?

concerns:
fluid bypassing
fluid returning to reservoir
no good pedal
plastic reservoir when normal cast

 

[cbrTodd]

Judging from the 1988 date you mentioned, the lower position of the heater air intake vent, and the flapper on the exhaust stack, it sounds like you have one of the later trucks that has the dual circuit brakes. I have no working knowledge of those other than that they have a split circuit master cylinder and two air packs. So the system you have may not match the 'normal' diagrams if that is what you are using.

 

[HDN]

I believe the trucks with dual-circuit brakes all had a plastic brake fluid reservoir up through the M35A3. If you aren't exactly sure about the brake setup on your truck, compare the brake diagrams you find in the TMs. There's also this diagram from the dual-circuit brake kit:

 

[ToddJK]

If that has dual circuit brakes, then it's a huge pro for that truck!

 

[GASCANS001]

Judging from the 1988 date you mentioned, the lower position of the heater air intake vent, and the flapper on the exhaust stack, it sounds like you have one of the later trucks that has the dual circuit brakes. I have no working knowledge of those other than that they have a split circuit master cylinder and two air packs. So the system you have may not match the 'normal' diagrams if that is what you are using.

What I’ll say is, I only see one air pack. I’ve done extensive research and can say I’m pretty familiar with the brake system.
When I flipped the trap door open and saw a plastic cap on a plastic reservoir I was complete thrown off.

i think it has the newer master cylinder but not the complete second circuit.

new style air pack.

is it possible to take apart the air pack and the mc and clean everything up without new parts?

 

[GopherHill]

What I’ll say is, I only see one air pack. I’ve done extensive research and can say I’m pretty familiar with the brake system.
When I flipped the trap door open and saw a plastic cap on a plastic reservoir I was complete thrown off.

i think it has the newer master cylinder but not the complete second circuit.

new style air pack.

is it possible to take apart the air pack and the mc and clean everything up without new parts?

I've done master cylinders and it worked ok.
I was very poor then and I don't recommend the practice.

 

[ToddJK]

I'm guessing the truck has no brakes at all? What is no good pedal? Just trying to get extra details.

 

[GASCANS001]

I'm guessing the truck has no brakes at all? What is no good pedal? Just trying to get extra details.

Pedal to the floor no resistance whatsoever.
If a partner holds the pedal to the floor and I crack a bleeder I do get some pressure but not a jet like it should be. It’s more of a little trickle.
Zero brakes. Absolutely no stopping ability. Not even the parking brake works. That’s a completely separate issue.

 

[GASCANS001]

I've done master cylinders and it worked ok.
I was very poor then and I don't recommend the practice.

Where could I find a rebuild kit? Considering the mc I have is not even close to what everyone else has.

Are the parts interchangeable?

 

[Gypsyman]

Do you have pictures of the underside of the truck? I don't see an '88 with all the signs of it being an AF truck with split brakes and a plastic reservoir not having the second air pack unless things have been drastically altered.

 

[HDN]

Do you have pictures of the underside of the truck? I don't see an '88 with all the signs of it being an AF truck with split brakes and a plastic reservoir not having the second air pack unless things have been drastically altered.

I think it's possible that a plastic reservoir was retrofitted to a single-circuit system. This is the DoD we're talking about after all. Plus some late 80s deuces have been shown to not have dual-circuit brakes.

Another major clue is the presence of dual-circuir brakes is a parking brake indicator light in the gauge cluster. That turns on when the parking brake is engaged or if the hydraulic part of the brake system loses pressure.

 

[GASCANS001]

I think it's possible that a plastic reservoir was retrofitted to a single-circuit system. This is the DoD we're talking about after all. Plus some late 80s deuces have been shown to not have dual-circuit brakes.

Another major clue is the presence of dual-circuir brakes is a parking brake indicator light in the gauge cluster. That turns on when the parking brake is engaged or if the hydraulic part of the brake system loses pressure.

to touch on this. There is a light for brake but not sure exactly what trips it. I havefound if the shifter for the trans is on a fence of a gear the truck willcrank but not actually crank more of a clunking sound. Almost like a neutral safety switch. Very weird.

 

[GASCANS001]

Do you have pictures of the underside of the truck? I don't see an '88 with all the signs of it being an AF truck with split brakes and a plastic reservoir not having the second air pack unless things have been drastically altered.

I do not however, I will get some soon.
Any good idea to keep water out of that cap so I can pressure wash the area of the air pack and such? It’s a pipeline truck and it’s caked everywhere.

 

[smoke]

You said that you bleed the m/c than furthers to nearest. Did you bleed the airpack after bleeding the m/c ? If you didn't start over m/c than airpack than furthest to nearest.

 

[GASCANS001]

You said that you bleed the m/c than furthers to nearest. Did you bleed the airpack after bleeding the m/c ? If you didn't start over m/c than airpack than furthest to nearest.

Well kinda think of it I think I bled the air pack then went back to front. I don’t think there was a bleeder on the mc

 

[BEASTMASTER]

pretty brave pulling 16k lds with a 6k ld p/u .

 

[GASCANS001]

pretty brave pulling 16k lds with a 6k ld p/u .

Can you reiterate?

 

[ToddJK]

Can you reiterate?

He's talking about your load vs the weight of the truck, since the deuce and trailer weight far exceed the weight of the pick-up.

 

[GASCANS001]

He's talking about your load vs the weight of the truck, since the deuce and trailer weight far exceed the weight of the pick-up.

If it fits it’s ships. 190 miles on the interstate like that

 

[GASCANS001]

Do you have pictures of the underside of the truck? I don't see an '88 with all the signs of it being an AF truck with split brakes and a plastic reservoir not having the second air pack unless things have been drastically altered.

Update

i have one long style and one short style air pack on the truck

I HAVE DUAL CIRCUIT BRAKES!!!!