Never ending brake nightmare

[WildEd]

I've replaced ALL the brake components. Master cylinder, air pack, wheel cylinders etc. I've blead the brakes several times, and can't get the #$@% system to build and hold pressure. There's no fluid leak, and the air system holds adequate pressure. What's the obvious culprit? I'm at my witts end and tired.

 

[Elijah95]

This may sound silly, but are you certain you’re completely bled? Some guys have a real good method, mine is I take a shop vac and crack the bleeders with a small hose on the port, suck it until the fluid is clear starting at the Airpack, followed by right-rear-rear, right intermediate, left-rear-rear, left intermediate, then front right, front left. All while keeping fluid topped off.

Oh speaking of which, on my second m35 my brake pedal return spring was MIA and the pedal wouldn’t return far enough to allow the plunger back, no fluid could go further down. Just a couple things to check


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[Katahdin]

SInce you didn't mention these:

1) Bleed with a pressure bleeder, do not use the foot method. You may be introducing air into the system by pumping with your foot.

2) Bleed the air pack first, then move to the furthest wheel out and work your way to the front axles.

 

[WildEd]

This may sound silly, but are you certain you’re completely bled? Some guys have a real good method, mine is I take a shop vac and crack the bleeders with a small hose on the port, suck it until the fluid is clear starting at the Airpack, followed by right-rear-rear, right intermediate, left-rear-rear, left intermediate, then front right, front left. All while keeping fluid topped off.

Oh speaking of which, on my second m35 my brake pedal return spring was MIA and the pedal wouldn’t return far enough to allow the plunger back, no fluid could go further down. Just a couple things to check


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Thank you sir. I forgot all about bleeding the air pack. Excuse me while I kick myself in the arse for awhile.

 

[WildEd]

SInce you didn't mention these:

1) Bleed with a pressure bleeder, do not use the foot method. You may be introducing air into the system by pumping with your foot.

2) Bleed the air pack first, then move to the furthest wheel out and work your way to the front axles.

I forgot all about bleeding the airpack. Thanks.

 

[Elijah95]

Nah man, you’re good! After a long day(s) work on a truck, it’s easy to miss a step; hopefully you’ll be back up soon keep us posted


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[WildEd]

This may sound silly, but are you certain you’re completely bled? Some guys have a real good method, mine is I take a shop vac and crack the bleeders with a small hose on the port, suck it until the fluid is clear starting at the Airpack, followed by right-rear-rear, right intermediate, left-rear-rear, left intermediate, then front right, front left. All while keeping fluid topped off.

Oh speaking of which, on my second m35 my brake pedal return spring was MIA and the pedal wouldn’t return far enough to allow the plunger back, no fluid could go further down. Just a couple things to check


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After rolling around in the dirt and gravel after work for the 3rd day, it appears that the airpack was indeed in need of being blead again. Thanks!

 

[WildEd]

I forgot all about bleeding the airpack. Thanks.

Yep, airpack needed bleeding again. Thanks!

 

[Elijah95]

That’s awesome! Glad we could help, we need pictures of the truck though *hint* *hint*


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[WildEd]

Here

 

[Robo McDuff]

At least in 5-tons, master cylinder has ONE and airpacks have TWO bleeding points.

 

[cattlerepairman]

Not in the 2.5ton. Master is not being bled and airpack has one bleeder valve.

 

[hndrsonj]

Deuce Power Bleeder R4x4 Style

Gang, here are 2 pics of my bleeder. You can see that the tank line has a ball valve and a quick coupler from an air line. It then connects to a second hose that has a tee and a 6" nipple that screws into the MC cap. There's a plug in the top of the tee but eventually it will have a pressure...

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