Brake pedal not coming back up

[wwwabbit]

Woohoo! I got it running! I just the diesel motor... ahhhh...

Anyway
So, I have done just about everything on the brakes.
New: lines, front pads, calipers, disks, rear wheel cylinders.

When the truck is off, you press the brake pedal and it goes down, and comes back up to full height.
When the truck is running, you press the brake pedal and it goes down with much less effort (so I know the booster is doing it's job) but the pedal won't come all the way back up, it stops about 1/2 way. If you pull up on the pedal it will come back up, it does not take much effort, but it does take some.

If I pull out the vaccum hose, it does not do it. So, my thought is that something is wrong with the booster, or the master brake cylinder (which I didn't change)

Hummm, I just thought of something. Could some air in the master cylinder cause this? It did drain out most of the fluid while I was changing all the brake stuff. I didn't take the master cylinder off and blead it, just added fluid and blead everything else (including the ABS thing for the rear)

 

[dazedandconfused]

If you bled everything else I dont think it is air in the line! I think you have a vacum problem myself!

Andy

 

[wwwabbit]

If you bled everything else I dont think it is air in the line! I think you have a vacum problem myself!

Andy

As in to much vacum? Can you have that? I know the vacum pump is new, and it looks like it. The pedal goes up and down normaly with out the vacum line attached to the booster. So would that be a booster problem, or a vacum pump problem?

 

[argve]

Never heard of one failing this way but I suspect the boost has failed... But that is just a guess.

 

[PackRat]

Sounds to me like the booster isn't venting properly, or the pedal linkage is binding, for some reason.

If you pull the vac line off, when the pedal is down, does it return correctly?

 

[dazedandconfused]

I had a similar problem on the old Chevy/Cummins truck I had! Found thier to be a kink in the vacum line! Maybe you have a pin hole in a line or like said above it is not venting properly!

 

[Agnem]

This may be a dumb question, but did it do this before you started working on the breaks?

 

[wwwabbit]

This may be a dumb question, but did it do this before you started working on the breaks?

I dunno... I drove it all of about 60 feet... once up and down the guys driveway, the other off the trailer and to the spot it's parked now. So I dunno...

I don't beleave the linkage is binding, as it does come all the way up with the vacuum disconnected.

I will give it a double check for kinked or squashed lines. It did seem to have lots of suck when I pulled it out (it makes a good sucking sound after I pull the vacuum line off the booster) Also putting my thumb over the vacuum line it definatly has some suck.

Where/how does the vacuum booster vent? Is there a vent hole or ? somewhere that I should make sure is clean?

Thanks guys. It's getting *SO* close I can feel it.