vacum brake

[ersim1]

I recently switched from Powermaster to a vacum setup. I am having a problem with low brake pedal and it is also slow to return. I suspect it is the checkvalve . Is it inside the booster?? Is it a b*^%h to change?

 

[Red Regal T]

CHECK VALVE IS THE PART PLUGGED INTO THE BOOSTER. JUST REMOVE AND REPLACE IF NEEDED. DID YOU CHANGE OUT YOUR BRAKE PEDAL? AFTER FIRST DEPRESSION OF THE BRAKE PEDAL, DOES THE PEDAL "PUMP UP"?

 

[ersim1]

Yes I changed the pedal...the brakes do not pump up , the pedal goes almost to the floor, and the pedal is slow to return??

 

[Nick Micale]

Sounds like it was not properly bled or a bad master cylinder.

The master cyl MUST be properly bled BEFORE hooking it to the system. If not, you then force air into the system which is very difficult to remove.

 

[ersim1]

Hmmm...I did bench bleed it ..and then bled all four wheels...I still have the steel proportioning valve but it was not a problem with the Powermonster...I will try a new check valve..then do the master if that does not work????Thanks for the help....

 

[granitestategn]

ersim1

I would suggest you take out the master cylinder and bench bleed it again. When you re-install it make sure you bleed it at the ports before you snug them up. Then bleed the rest of the system. Then see if you have a problem. I did this job last summer and had the same symptoms that you are describing until I did it a second time. (a little more carefully)

 

[6=8]

A bad check valve would give you a hard pedal, with no power assist. Try pressing the pedal a couple of times with the car turned off. I bet it will be more difficult to press to the floor even if you have air in the MC or lines.

Look for a leaking calipar or rear brake cyl. If these leak fluid, it would account for a soft pedal as well.

Bleed the brakes again as granitestategn suggests. Both the MC/Bench and all 4 bleeder screws.

I recommend getting those expencive "HELP!" bleeder screws! Man, those things kick ass! Just open them a little, attach a hose to the bleeder screw, run it to a can, and pump away! They have a check valve in them, so air never finds its way in.

 

[edwin]

quick bleeder ?

what do those quick bleeders go for and also the other day the hose from the check valve popped off and i lost the brakes for a minute,reconnected and then a week later i put in the s10 wheel cylinders but no difference(wont hold 3 psi)can this be the problem(9will hold 5 psi with e brake sometimes) not too practical with drums but they are installed correctly,i dont get to work on cars with drum brakes at work much(audis)

 

[Steve Wood]

after the mastercylinder is properly bled, if it is not, then simply open all the bleeders, put a piece of vacuum hose over each one to catch the drainage in a jar, and let them gravity drip until you have fresh fluid in all the jars. Be sure to keep the mastercylinder full.

You can tap the rear cylinders with a plastic hammer to dislodge any air bubbles that might be hanging to the sidewall of the cylinders.

 

[ersim1]

I found out my problem with the erratic brake pedal....it was stupidity...when i switched to vacum brakes i hung the pedal wrong ..completely missing the upper bushing hole ( who says when you get older you get smarter)...I rehung the pedal right put in a new checkvalve which was bad and everything is OK...

 

[6=8]

Great!

Glad to hear that you found the trouble, and took a moment to let us know. More than 1 problem at the same time is always tough to diagnose.

That one on top is a P I T A!

Not only is it hard to see, it is a 1 man job.

My friend said I should just drill a hole in the firewall and be done with it.

Nice job!

 

[Steve Wood]

Hey, us old guys just like to practice a bit to make sure it is right!