Deuce brake mystery

[movcondude]

This has become a full size mystery to me so hope some of you Garage gurus out there know what could cause the problem...

I have been all around the bleeder screws including the booster for several times so the brakesystem should be absolutely free from airpockets. I have a hard pedal on and the brakes works perfect (this far). Now to the mysrery part - When I start her up and she start build up airpressure the pedal goes from hard at 3/4 up down to 1/4...

Any suggestions ?

 

[Computerdoc08]

Maybe a malfunctioning air pack?

 

[Ferroequinologist]

Definitely an airpack issue. They do make rebuild kits.

 

[G744]

Make sure your service line output isn't leaking air upon application.

DG

 

[movcondude]

Thanks a lot Guys - Your replyes has all been wery helpfull and are highly appreciated !

I will roll under the truck and take a good look on that Booster

Thanks again !

 

[ToddJK]

I would think it's the air pack. Make sure the air tanks are drained of any water as well.

 

[Mullaney]

Thanks a lot Guys - Your replyes has all been wery helpfull and are highly appreciated !

I will roll under the truck and take a good look on that Booster

Thanks again !

.
Hard part is that just looking at the booster won't tell you a lot... Not that looking isn't good - looking for drips and such - but a rebuild kit is about the best fix.

 

[ToddJK]

.
Hard part is that just looking at the booster won't tell you a lot... Not that looking isn't good - looking for drips and such - but a rebuild kit is about the best fix.

I dunno, "just looking" solves a lot of stuff, for me anyways!

 

[Ferroequinologist]

I dunno, "just looking" solves a lot of stuff, for me anyways!

Unplug it, and plug it back in. Still doesn't work? Hit it with a hammer. Still no joy? You obviously need a bigger hammer...

 

[INFChief]

Are you loosing air pressure? What is your running air pressure?

Did you bleed the brakes like this:

Master cylinder; brake booster, then farthest wheel away working back toward the closest wheel to the master cylinder?

 

[ToddJK]

Unplug it, and plug it back in. Still doesn't work? Hit it with a hammer. Still no joy? You obviously need a bigger hammer...

Haha, exactly.