brake pedal throbing loud humming

[bayboy87natl]

newbie to site, my 87 gn has recently started humming very loud from the powermaster area can feel it vibrating also the motor wont shut off.My brake fluid is black and the pedal is soft and will only go so far than hard as a rock.I have drove it with the unit being unplugged i still stop but pedal is hard.I am not driving it anymore until i fix it.Could it be i just need the new powerbrake master w/out cylinder.Or could it be a brake line issue like air in the lines.Sorry if i am all over the place in regaurds to my post.Thanks for any help i have owned my gn for 8 years i just dont know others w/ gns

 

[TRICKSIXPA]

Well the main thing a power master does is it builds pressure when the car turns on to assist with the braking. If your motor stays on then there might be a leak at the check valve which is located behind the hard line that comes from the motor to the master cylinder. it's building Preassure but the system is not holding it so the motor stays on.
You MUST run the power master with Clean brake fluid.
The brake fluid should be changed at least once a year to keep the motor in a running condition as well the rest of your brake system should be checked especially the rubber hoses. Is your brake light staying on? What is your location? These Power masters are not easy to work on if you are not familiar with them. It might be easier for you just to go to a Junk yard and get a regular Vacuum setup.

 

[TurboDave]

Oh, boy! Where do I start?? Absolutely everthing that could have been done to abuse and ruin that powermaster system has been done.
1. Ignoring problems when they starte
2. Dirty fluid never changed
3. Continued ignoring problem causing even more damage to an already ruined system!!!

Please forgive me for saying so, but if that's the way you're going to continue to treat your braking system (even after you fix it $$$$$), then I would advise you convert to vacuum. They're a bit less susceptable to owner abuse.

 

[bayboy87natl]

yes brake light is on i am located in northern cali

 

[bayboy87natl]

i had no idea it was so fragile, ihave owned 2 turbo T s and my 2nd gn never had a brake problem

 

[TRICKSIXPA]

Well consider your self fortunate for not crashing your car. Search the forum here and find out what you need to convert your system to a brake booster setup/Vacuum. It's less mantainace but don't feel bad your not the only one who has driven around with black brake fluid in there PM. I probably would have to when I first got my car had it not had the Brake light on. After looking into it and doing the reading I learned what I need to do to keep them operating. SO YOU KNOW turn the car off and press the brake pedal ten times to depressurize your system before you start taking anything apart.

 

[TurboDave]

i had no idea it was so fragile, ihave owned 2 turbo T s and my 2nd gn never had a brake problem

They are no more fragile than anything else if properly cared for. They just can't hold up to abuse and neglect.

 

[1quick6]

I'd agree with TurboDave. The Powermaster as a whole likes exercise, care and cleanliness. A lack of any of these will bring you trouble in a hurry.

 

[~JM~]

Here is a write up on swapping to vacuum brakes if you decide to go that route.
Vacuum Brake Install

~JM~