Rebuilt air pack why wont brakes release?

[Slate]

I recently rebuilt my air pack on my M54A2. Why won't my brakes release now? Seems to work fine brakes in and release air comes out tube. Everything moves correctly. A little help please?

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[ehinlein]

I recently rebuilt my air pack on my M54A2. Why won't my brakes release now? Seems to work fine brakes in and release air comes out tube. Everything moves correctly. A little help please?

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Is I adjusted so there’s slack in pedal rod? Needs to fully extend in cylinder to bleed off when pedal released.

 

[Slate]

Pedal is all the way up on master cylinder. If that's what you mean. It comes to the point where it has just a little slack in it.

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[Floridianson]

Don't quote me but was there not a small bleed back hole in the master cylinder . If that get plugged up fluid can not bleed back to master.

 

[Slate]

Don't quote me but was there not a small bleed back hole in the master cylinder . If that get plugged up fluid can not bleed back to master.

Bled well. And brake pedal is a rock

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[Slate]

Bled well. And brake pedal is a rock

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I even went over and over and didn't have any spare parts. After rebuild? I'm stumped. The system bleeds off it just takes all day

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[Slate]

This little guy is the only bleeder that doesn't shoot fluid. It just trickles a little.

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[Slate]

This little guy is the only bleeder that doesn't shoot fluid. It just trickles a little.View attachment 793885

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Can the piston on the back of the can get stuck on one side or the other, when put back together? Just thinking through it.

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[98G]

What James means is the fluid doesn't return to the master cylinder like it should when that little hole is plugged.

You should see a vigorous return, sometimes even squirting out the top of the fluid level.

 

[Slate]

What James means is the fluid doesn't return to the master cylinder like it should when that little hole is plugged.

You should see a vigorous return, sometimes even squirting out the top of the fluid level.

I've got fluid that squirts back up when pedal released. Both holes seem to be clear in master. And I can hear piston in air pak go back and forth when brakes applied. It does that untill pressure builds up in lines and them pedal won't push anymore. And then no more squirting or anything for a bit. The lines build up pressure for about 10-15 min, and brakes are lock for that time. I'm missing something. Maybe a bug crawled in there last night while it was sitting on my bench. Frustrating master worked fine befoe, only airpack died. So I think.

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[Monkeyboyarmy]

One of the lines on the front glad hands under the front bumper needs to be vented. Any chance you capped that off or plugged that line somehow?

 

[Slate]

One of the lines on the front glad hands under the front bumper needs to be vented. Any chance you capped that off or plugged that line somehow?

No glad hand on the front of this old girl.

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[98G]

One of the lines on the front glad hands under the front bumper needs to be vented. Any chance you capped that off or plugged that line somehow?

I think that is specific to the 939series trucks. Someone correct me if I'm wrong.....

Edit - I'm wrong. Thanks

 

[Monkeyboyarmy]

Well that's why my 816 locked up going down the road when I picked it up from the drmo to drive it home. Peddle got rock hard.

 

[Slate]

Well that's why my 816 locked up going down the road when I picked it up from the drmo to drive it home. Peddle got rock hard.

Maybe on the little air regulator side I was to generous with the cleaning and not enough with the lubrication. I'll probably take that side back apart and check it out. I know the can and piston are good. I spent a lot of time on that.

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[fasttruck]

The service front glad hand on a 39 or 809 series truck is typically mounted on the hanger that supports the front of the right front fender. The air line runs down the frame rail and comes out to the fender support. This has a glad hand dummy connector on it which is vented to the atmosphere so the air charge in the applied brake lie has a means to escape when the pedal is released. As this truck has had some farmer repairs to the front bumper structure who knows what they did with the line and the vented connector.

 

[Slate]

The service front glad hand on a 39 or 809 series truck is typically mounted on the hanger that supports the front of the right front fender. The air line runs down the frame rail and comes out to the fender support. This has a glad hand dummy connector on it which is vented to the atmosphere so the air charge in the applied brake lie has a means to escape when the pedal is released. As this truck has had some farmer repairs to the front bumper structure who knows what they did with the line and the vented connector.

This explains the first pic. It's always been crimped since I got it from fire dept. Was a Texas forest service truck. Maybe that why the pak failed. Next is the vent on top of air pak. Was this connected to glad hand at front or was this separate? Lastly just a random line crimped off near air pack. Lots of "Farm" mods before I got the truck. It was free so I'm not complaining.

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[fasttruck]

Sometimes "free" will put you under water after you fix all the stuff that is broken. The Army's deep water fording ideas sees many items such as the vents on the master cylinder, crankcase, transmission etc piped into the air cleaner to keep water out.


Aattached are pics pf the vented glad hand used on the front service towing air connection. This allows the brakes to release by venting the air out.
If you are not going to drive the truck in water or mud maybe you can spread the crimped end to make a vent.

 

[Slate]

The tube that had the crimped tube on it is a service tube not a vent all it does is drain tanks. The one you show in your pic is on passenger side looks looks like. I have a hole where the one in your pic is but no line. I'll figure it out or just drive it with no brakes. Down shifting to stop. Been doing that for a few years now, cause I didn't have the time to fix air pack.

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[Slate]

I do have a question when bleeding the bleeder circled in red. Should it have pressure on it like the rest of the system or should it just trickle? Because everywhere else there is plenty of pressure but this one just trickles.

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