problem w/ stopping my turbo buick!!!

[cecil bass]

do you guys think this problem can be caused if when the car was converted over ro vacuum brakes they didnt change the brake pedal?

 

[BGNeXtreem]

If you had a power master and converted to vac brakes and didn't change the pedal or at least modify it the answer is yes you could have a big problem I got mine off of an olds 442 when I got the booster and master cylinder also got the pedal no issues for 7 years now

 

[Turbo Loyd]

Here are some quick tests to see if the booster is working correctly

Hope this helps

 

[Turbo Loyd]

If you had a power master and converted to vac brakes and didn't change the pedal or at least modify it the answer is yes you could have a big problem I got mine off of an olds 442 when I got the booster and master cylinder also got the pedal no issues for 7 years now

Petal from powermaster on left and standard petal from vacuum brakes on right. The pin is bigger in diameter and too high to use with a vacuum booster.

 

[hesermon]

If the pedal is hard that is lack of power assist, that comes from no boost from your brake booster. Either the booster is not getting enough vacuum or it is getting vacuum and not converting it to boost. First determine if you are getting vacuum. Pull the hose off the booster at the check valve (the black plastic plug that attaches the hose to the booster). Put your finger over the end of the hose and have someone start the engine, the vacuum should hold the hose to your finger. This is not going to tell you how much you have but at least if you have some. If it will "suck" to your finger if have vacuum and should at least have a decent pedal when you first apply the brakes when driving. If it's not enough you will only have good pedal until it builds vacuum again (from normal driving). Next test, put the hose back on and let the car idle for just a minute, shut it off then immediately pull the hose off of the check valve. Nothing should happen because if working properly the check valve traps the vacuum inside the booster. Next pull the check valve, now you should get a pretty big "whoosh" of vacuum bleeding off. If you don't hear the "whoosh" then you are not holding vacuum, the booster is bad.
Anything other than lack of vacuum (i.e. air in the line, low on fluid) will not make the pedal hard but rather it will be soft. The only other thing that could make you pedal hard is a frozen caliper, in that case the car should dive to the side of the one that is not frozen when you apply the brakes.
The incorrect pedal will not affect hardness, it only affects the distance the pedal travels. (If not changed the pedal will touch the floor too soon.)
Also, the ideal place to get vacuum from is the block on top of the plenum, if you don't have the brake port on it (stock from a PM car), put a "t" above the PCV valve and draw from there.

Hope this helps!

 

[cecil bass]

thanks you guys !!!!! you have so much info to share and trust me im taking it all in! i wouldnt know what to do if i didnt have this forum !! you guys are great i cant wait to get home so i can tackle this problem . ill let you guys know how it goes...

 

[cecil bass]

i just got home finally ..... i tested the vacuum presure from the line going into the booster its showing 13" of vacuum. the check valve from the booster was blocked with a broken screw like done intentional. so i got another booster check valve and i also got a new power brake filter. new problem now when in idle the check lite comes on sometime but when i raise the idle or when driving the light goes out ...... i really need some help on what can be now ??? i really dont know whether to get another booster or what ? can one of my brake calibers be messed ???????

 

[hesermon]

i just got home finally ..... i tested the vacuum presure from the line going into the booster its showing 13" of vacuum. the check valve from the booster was blocked with a broken screw like done intentional. so i got another booster check valve and i also got a new power brake filter. new problem now when in idle the check lite comes on sometime but when i raise the idle or when driving the light goes out ...... i really need some help on what can be now ??? i really dont know whether to get another booster or what ? can one of my brake calibers be messed ???????

Do you know how to check the SES light to see what code is being set? I can't imagine why anyone would block off the check valve unless the booster is bad and they did it to hide the fact that you have open vacuum leak (inside the booster), with it plugged vacuum cannot be pulled through it so that would explain no power brakes. You did not say if you have better brakes now.

 

[turbojd]

I just re-drilled my power master brake pedal when I converted to vacuum brakes. I also did the S10 Blazer dual piston brake set up, that made a noticeable difference in the stopping power.

 

[CGASTON]

here's a picture of the setup that I have..... can anyone tell me how I could check how much vacuum the booster is getting before I proceed with getting any new parts. thanks guys!!!

First, stop and think about your brake system. The brake booster is there to help reduce the pressure that you are apply from the brake pedal to the master cylinder. Hydraulic Brake systems were never design to require the pedal to be depressed all the way to the floor. SOMETHING TO REMEMBER IN A GOOD BRAKE SYSTEM, IS THAT IS ONLY REQUIRES 1tsp OF BRAKE FLUID TO OPERATE BRAKES AND STOP THE VEHICLE. You should only apply pressure to the pedal 1/2 - 3/4 and the car should stop.

The master cylinder has two pistons in it, one for fronts and one for rear. These pistons cover and control brake fluid to two ports in called vent port and the replenishing port. The vent port is basically where your brake pressure is built. The replenishing port keeps fluid behind the piston to maintain pressure.

With this said and you having to apply so much pressure to the pedal, I would lean towards the pistons being stuck or sticking in your master cylinder. What I would do is to break the line loose at the cylinder and see if you get brake fluid to run out. Now if you do, then you found your culprit. You have a stuck piston.