No Brakes at all - pedal goes to floor

[TXMIDGUFFREY]

Expert experienced advice please.

'71 M35a2 - brake pedal goes to the floor, no resistance, master cyl is full, no air leaks

Troubleshooting guide leads me to "Air-Hydraulic Cylinder"

I found a rebuild kit at Mike's Motor Pool but it calls it M35A2 2.5 TON AIR PACK REBUILD KIT 8345007

Am I on the right track with this?

 

[gimpyrobb]

Make sure to adjust and bleed the brakes first. Have you been in the hubs to verify the wheel cyls are good? If not, its time to take a weekend and do it.

 

[Big Tom]

It all needs a good going over to be safe for shure, go under and pull rubber boot back on master cylinder and see if piston is stuck all the way in.

Big Tom

 

[frank8003]

https://www.steelsoldiers.com/showt...c-air-hydraulic-airpak-air-hydraulic-cylinder

 

[TXMIDGUFFREY]

I'll do the bleed for sure. Where can I find info on going "in the hubs to verify the wheel cyls are good"

 

[cattlerepairman]

https://www.steelsoldiers.com/showthread.php?8460-Front-axle-seals-and-boots-stepXstep

This is a good starting point if you have never taken the brake drums off your truck.

 

[Kaiser67M715]

**So, I'm going to add to this, as I lost pedal in my truck this afternoon, If the Moderators feel This should be a separate thread, please move.**

I do still have "brakes" it will hold on an incline, but I'm probably only 1/2" from floor. No Fluid loss(that I can see in reservoir, pumping brakes multiple times did not bring the pedal back up, nor did the fluid level drop) I am also leaning towards an Air Pack failure, but would like a second opinion.

I will also say I did my annual brake inspection 2 or 3 weekends ago, removed hubs, and pulled back all the dust boots, everything that should have been dry was dry. Pedal feel this morning I would say was normal, fluid was at top level mark. Again, just looking for a second opinion, I will be going through the whole system.

 

[davidb56]

**So, I'm going to add to this, as I lost pedal in my truck this afternoon, If the Moderators feel This should be a separate thread, please move.**

I do still have "brakes" it will hold on an incline, but I'm probably only 1/2" from floor. No Fluid loss(that I can see in reservoir, pumping brakes multiple times did not bring the pedal back up, nor did the fluid level drop) I am also leaning towards an Air Pack failure, but would like a second opinion.

I will also say I did my annual brake inspection 2 or 3 weekends ago, removed hubs, and pulled back all the dust boots, everything that should have been dry was dry. Pedal feel this morning I would say was normal, fluid was at top level mark. Again, just looking for a second opinion, I will be going through the whole system.

wouldn't you lose fluid if it is a air pack issue? I'd be inclined to give the master cylinder a closer look.

 

[Kaiser67M715]

wouldn't you lose fluid if it is a air pack issue? I'd be inclined to give the master cylinder a closer look.

my thought was I would lose fluid or all brakes if it was the master...but I guess I'm not 100% sure. I need to find a way to get it home first.

 

[davidb56]

If the rubber cup on the piston in the master cylinder is scored, fluid will pass by it and you wouldn't lose fluid.