Vacuum holding brake pedal down!

[Dfnsmn34]

Aloha! I redid my brakes. Put a new MC and Power booster. Changed a few lines, bleed them all. Changed a Wheel cylinder that was not flowing fluid. Brakes work. But when I push the brake pedal the brake pedal stays down. maybe a few inches? (I can't tell if the brakes are still engaged).THIS I know, the Booster is holding it. When I pop the vacuum line the brake pedal goes back to it's resting place.

What am I doing wrong? I measured (a lot of times) the push rod from the booster and the rod isn't dragging or sticking. Vacuum is good...Booster is brand new too. Check valve is made to flow towards the intake.

I may need to bleed the brakes...don't think so...but that wouldn't have to do with the booster holding the pedal down.

The booster vacuum seems good too. I start the car and the brake pedal drops a little indicating the booster is doing its thing.

any guidance? Mahalo!

oops its my 66 barracuda 10" drum stock brakes, dual master cylinder and new distribution valve.

 

[67Dart273]

Bad booster

 

[BillGrissom]

Agreed. The booster should act just as a "follower". For some reason, it doesn't follow the pedal back. Might have a bad valve inside. To test it, you can remove from the pedal and MC and push the rod in and out by hand (with engine running to give vacuum) and see if it follow your motion, with assist. Of course, your MC may be missing the return spring. Test that while off the booster, using something like a 1/4 socket extension to push the piston in.

 

[Dfnsmn34]

Seems odd the booster would be bad. Not that anything new can't be bad. Just odd. It holds vacuum, pedal drops a bit when the engine starts. What are the signs if there's not enough vacuum? The original factory booster had the reserve canister (black box) that I haven't re installed. I was thinking of putting that in... But I'm not sure how to "tube" it in to be beneficial. It originally went straight to the bendix factory booster. Could I just splice it in line with the vacuum tube? Or do I need a check valve for that too?

Oh and I removed the MC from the booster and it responded the same way. Could it be that drop is natural for the pedal and booster? As weird as that sounds. Also, doesn't seem the brakes are engaged. More testing to follow. To be sure.
Mahalo for the help.


Here is what I installed.

http://www.ebay.com/itm/221025922112#ht_558wt_689

 

[Oklacarcollecto]

Seems odd the booster would be bad. Not that anything new can't be bad. Just odd. It holds vacuum, pedal drops a bit when the engine starts. What are the signs if there's not enough vacuum? The original factory booster had the reserve canister (black box) that I haven't re installed. I was thinking of putting that in... But I'm not sure how to "tube" it in to be beneficial. It originally went straight to the bendix factory booster. Could I just splice it in line with the vacuum tube? Or do I need a check valve for that too?

Oh and I removed the MC from the booster and it responded the same way. Could it be that drop is natural for the pedal and booster? As weird as that sounds. Also, doesn't seem the brakes are engaged. More testing to follow. To be sure.
Mahalo for the help.


Here is what I installed.

http://www.ebay.com/itm/221025922112#ht_558wt_689

Call the seller at 678 995 6488 and see what he has to say since you bought a complete unit.

He has the A body cars listed in the interchange but B & E bodies listed in the ad.

Dodge/Plymouth B & E body New 7" dual diaphragm brake booster with 1 1/8" bore master cylinder. This system is a direct bolt on to your firewall and will connect directly to your brake pedal if you have a factory non power brake car. Cars with factory power brakes will require slight modification to make fit. This system will power front disc/rear drum, 4 wheel drum, and 4 wheel disc brakes. These are top of the line MBM parts not cheap knock offs. All parts come with a full 1 year warranty. See our other listings for other variations of this system.

 

[Dfnsmn34]

I sent him an email. He was very helpful in the past. Just want to make sure I'm troubleshooting it correctly. I actually had to change the MC to a different style because my oil cap for the commando valve covers hit the MC. Since I'm running drums all around I used this one and it is the same one we use on my dads 67 d 100.

[ame="http://www.amazon.com/gp/product/B001PYO1G4/ref=oh_details_o00_s00_i00"]Amazon.com: Dorman M71259 Master Cylinder: Automotive[/ame]

 

[CudaChick1968]

I sent him an email. He was very helpful in the past. Just want to make sure I'm troubleshooting it correctly. I actually had to change the MC to a different style because my oil cap for the commando valve covers hit the MC. Since I'm running drums all around I used this one and it is the same one we use on my dads 67 d 100.

Amazon.com: Dorman M71259 Master Cylinder: Automotive

A quick off-topic Thank you .......... :-D It breaks my heart to think of post-work modifications Mike (thus our talk about the knock out on your dad's valve covers a couple weeks ago heh hehh).

 

[Dfnsmn34]

LOL Leanna...

so I did nothing...decide to go on a short cruise with the vacuum line disconnected...thats a no go...gotta stand on the brakes to get her/them to stop. (DUH power brakes)

well hooked it back up....brakes work great! I DID NOTHING! WTF...i want to FIX something...not it fix itself!

MOPAR's are possessed right? Christine?

[ame="http://www.youtube.com/watch?v=aJ5M11m9vI0"]Christine (1983) theatrical trailer - YouTube[/ame]