Brake Issue M51A2

[Recovry4x4]

So, I finally mustered up the courage to move the M51A2 to my sister in laws house. It's been parked at the VFW for a couple of weeks. Prior to this it was at my church until I got it running. Driving around the parking lot at church it seemed to have a catch in brake pedal travel. I would feel some resistance then the brake would apply fairly hard. Well, today at a stop light, I was applying brakes when the pedal firmed up and rose up a couple of inches. Did a few tests before I left the traffic light. At my next turn while slowing, the pedal did the same thing and it took quite a bit of pedal pressure to slow it down. I know brakes fairly well but I'm more familiar with deuce brakes over a 5 ton. I'm quite certain that I have an air pack issue. I just can't see anything else in the hydraulic side causing this. Oh, air pressure was fairly consistent at around 90 PSI. Does anyone else see anything I'm missing? Hopefully I can find rebuild kits for this

 

[Ajax MD]

It's sticking a bit. Mine did this exactly once. It's why you drain the air tanks- to get moisture out of the system.

I can't say if yours is closer to failure.

 

[Ferroequinologist]

Sounds like what my deuce was doing- air pack backfeeding into the master cylinder. So takes more pedal force to get the fluid to go the right way. Usually a check or port not sealing.

If you want I have a good takeoff m39 air pack I can lend you to swap and see if that fixes it.

 

[Recovry4x4]

It's sticking a bit. Mine did this exactly once. It's why you drain the air tanks- to get moisture out of the system.

I can't say if yours is closer to failure.

Thanks, I am acutely aware of the need to drain air tanks.

Sounds like what my deuce was doing- air pack backfeeding into the master cylinder. So takes more pedal force to get the fluid to go the right way. Usually a check or port not sealing.

If you want I have a good takeoff m39 air pack I can lend you to swap and see if that fixes it.

I may just open up the can and see how it looks. If not bad, maybe hit it with a dose of air tool oil. If I can't resolve it, I'll likely just rebuild it. I may, however, call on you to bring the air pack to Denton just in case.

 

[Ferroequinologist]

I may just open up the can and see how it looks. If not bad, maybe hit it with a dose of air tool oil. If I can't resolve it, I'll likely just rebuild it. I may, however, call on you to bring the air pack to Denton just in case.

It's already in the truck...

 

[Recovry4x4]

Thanks brother.

 

[BKubu]

Kenny, I believe that you have an air pack issue. I once had a bad air pack in an M813A1 and you had to literally stand on the pedal to get the truck to stop. This sounds like what is happening to you. Fortunately, aside from the expense for the air pack, it is a fairly easy swap.