Viewing a thread - New/rebuilt booster pulls and holds vacuum

You are logged in as a guest. ( logon | register )

New/rebuilt booster pulls and holds vacuum Jump to page : 1 Now viewing page 1 [50 messages per page]	View previous thread :: View next thread
Forward Look Technical Discussions -> Brakes, Wheels and Tires	Message format

b5rt

Posted 2016-09-18 5:46 PM (#521552)
Subject: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 2519
2000

Location: central Illinois

New rebuilt booster, new master cylinder, new wheel cylinders and shoes. Bled brakes with everything connected and have good pedal. Adjusted cams and shoes are properly adjusted. I fired up the rebuilt 383 for the first time and the Booster Dewey rebuilt bellows sucked all the way in and pulled the brake pedal to the floor. The only way it would release is by loosening the hose (picture) from the check valve T. Then the bellows released and pedal is no longer on the floor.

Do I have the check valve installed correctly? I can't see it being any different because of the size of hoses.
Did bleeding brakes with the bellows never having vacuum on it cause it to pull in?

I've got a transmission leak, probably the o-ring on cable, so won't be firing it again till I get that resolved but hoping for some good input on what to check for on the booster.

(IMG_3559.JPG)

Attachments
----------------

IMG_3559.JPG (106KB - 144 downloads)

ttotired

Posted 2016-09-18 7:13 PM (#521560 - in reply to #521552)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert 5K+

Posts: 8443
5000

Location: Perth Australia

Check whats going on at the top of the pedal arm, there is a valve thats part of the booster that should be closed at rest and get released to open when the pedal is pushed

I think you have the check valve right, but hard to say without seeing where the hoses are going.

b5rt

Posted 2016-09-18 8:10 PM (#521563 - in reply to #521552)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 2519
2000

Location: central Illinois

The photo rotated when uploaded. The hose at the red end of T goes to intake manifold, the opposite side of T goes to the vacuum tank under battery.

I'll check underdash tomorrow but not real sure what to look for.

hemidenis

Posted 2016-09-18 8:52 PM (#521566 - in reply to #521552)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 3887
2000

Location: Northen Virginia

the red side part of the T is where the valve is, the air should only flow to one direction and it is to the direction of the intake so the engine can "suck" air from the bellows.. I think your T is connected right, but is easy to test if you can suck air from the T valve but not blow air. The tank is a Vacuum tank to hold some extra vacuum.

By the way your restoration looks top notch, congratulations.

Edited by hemidenis 2016-09-18 8:54 PM

(IMG_3559.JPG)

Attachments
----------------

IMG_3559.JPG (110KB - 135 downloads)

57chizler

Posted 2016-09-19 2:05 PM (#521628 - in reply to #521560)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 3774
2000

Location: NorCal

ttotired - 2016-09-18 4:13 PM

Check whats going on at the top of the pedal arm, there is a valve thats part of the booster that should be closed at rest and get released to open when the pedal is pushed

Yes, the adjustment of the trigger arm on the pedal is critical, if misadjusted the brakes will apply as soon as the engine is started.

http://restorecarsclassifieds.com/wiki/show_pdf.pdf?n=9893

ttotired

Posted 2016-09-19 6:13 PM (#521642 - in reply to #521552)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert 5K+

Posts: 8443
5000

Location: Perth Australia

The shaft that comes out of the booster with the forks that engage the pedal. in the middle of that shaft there is a plastic button, when that button is out, it allows the booster shaft to come out (basically chasing the brake pedal) until it catches up and is depressed about 1/2 way. If that button is depressed a bit more (taking your foot off the brake) the booster shaft should retreat allowing the pedal back up to the rest position.

Its hard to see the button with the booster mounted, but it must be stuck in the "out" position, you might be able to feel it with your finger.
Word of WARNING, dont play with the button while there is vacuum to the booster, its very powerful and it will bite you and not care that you are swearing at it to get it to let go of your finger.
Just a rumour I heard

My guess is the shaft and forks are not engaged with the top of the pedal, its the wrong pedal/somethings missing, or its just an adjustment.

b5rt

Posted 2016-09-21 7:38 PM (#521828 - in reply to #521566)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 2519
2000

Location: central Illinois

hemidenis - 2016-09-18 7:52 PM

the red side part of the T is where the valve is, the air should only flow to one direction and it is to the direction of the intake so the engine can "suck" air from the bellows.. I think your T is connected right, but is easy to test if you can suck air from the T valve but not blow air. The tank is a Vacuum tank to hold some extra vacuum.

By the way your restoration looks top notch, congratulations.

The valve checked out good. Thanks Dennis, now you can see why I wanted those tail light lenses.

b5rt

Posted 2016-09-21 7:45 PM (#521829 - in reply to #521552)
Subject: Re: New/rebuilt booster pulls and holds vacuum

Expert

Posts: 2519
2000

Location: central Illinois

Got time to look at it today and a buddy came over to have a look. We read the shop manual sheet chizler posted... a few times and crawled under to have a look. Like Michael said, there's a little white button on the booster that must work the valve. It appeared to be properly adjusted. We decided to give it another shot now that the hose had been unhooked and everything was reset from the vacuum overload. Reconnected the hoses and reset clamps. Fired the engine up for only the 2nd time and the booster stayed out as it should. Pumped on the brake pedal a few times and it appears to be working properly now! Not sure what happened to make it do what it did, just happy I didn't have to take the pedal, master cylinder and booster off again.

Thanks for the help guys! I've got to reinstall the steering column then I can take it for a short ride in the yard. First time under its own power in 4 years.

Edited by b5rt 2016-09-21 7:48 PM

Jump to page : 1
Now viewing page 1 [50 messages per page]

Jump to forum :

Search this forum
Printer friendly version
E-mail a link to this thread

* * * This site contains affiliate links for which we may be compensated * * *

(Delete all cookies set by this site)