1995 GMC Sierra Hard Brake Pedal

NFAFFSMITH867

MEMBER
1995 GMC SIERRA

Brakes problem
1995 GMC Sierra V8 Two Wheel Drive Automatic

My Brake Pedal Was Hard So I Checked The Brake Fluid And It Was Low, But Above The Minimum Level. So I Added Fluid To The Full Mark And The Pedal Is Still The Same. A Friend of Mine Said There Could Possibly Be Fluid In The Brake Booster, And Also There Could Be A Vacuum Leak, But There Is No Vacuum Leak That Was Checked. I Know That I need Brake Pads But They're Not That Bad. Could That Have Something To Do With This?

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

HARD BRAKE PEDAL

Lack of power assist may be due to low engine vacuum, a leaky vacuum hose or a defective booster. Sometimes a faulty check valve will allow vacuum to bleed out of the booster causing a hard pedal when the brakes are applied. This condition can be diagnosed by starting the engine (to build vacuum), shutting it off, waiting four or five minutes, then trying the brakes to see if there is power assist. No assist means a new check valve is needed.

A quick way to check the vacuum booster is to pump the brake pedal several times with the engine off to bleed off any vacuum that may still be in the unit. Then hold your foot on the pedal and start the engine. If the booster is working, the amount of effort required to hold the pedal should drop and the pedal itself may depress slightly. If nothing happens and the vacuum connections to the booster unit are okay, a new booster is needed (the vacuum hose should be replaced, too).