New owner, crazy humming noise from Master Cylinder

[roby]

Hey guys. New owner here, picked up a 7500mi '87 GN last Friday. Got it home and car has started to make an awful humming noise. I can feel the noise through the steering column and the pedal. At first it was intermitent at idle but now it continues most of the time. When it gets up to speed or after 30 mins or so it usually stops until you are back at a stop.

Popped the hood today and the noise is generated at this line that attaches to the master cylinder. Any ideas what it could be? Thanks for the help in advance.

 

[fastblackracing]

Sounds like your power master brake system may be bypassing fluid internally. The brake system on these cars are different from your normal ride and they have and will fail without warning leaving you with very little or No brakes. Do a search here for powermaster problems/ Issues to get a better understanding. And I would advise to not drive the car until you have the problem fixed. For real.

 

[TRICKSIXPA]

That line goes into the master cylinder there is a Poppet check valve inside the seal can get worn down or dirty. If the brake light is on then there is a problem. If the motor is running might have a pressure switch going bad or that valve is not closing. Make sure to press your brake pedal when the car is off to depressurization the system. Then you can work on it. There are good Power master trouble shooting guides to look up on gnttype.org


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