The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

Wrenchbender Ret · 04-14-2010, 04:43 PM

With the engine off pump the brakes 2-3 times. Then hold pressure on the pedal & start the engine. The pedal should drop a little. Seems like you are not getting vacuum to the booster or the booster is bad. It's not air in the system, that would cause a low pedal. Pull the check valve out of the booster. With the engine off you should get a short sucking noise. When you start the engine ther should be a strong vacuum at the checkvalve & the engine will run rough &/or fast. It's possible you have the adjustment on the rod between the MC & booster too long.

04-14-2010, 04:43 PM	#2
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: Brake problems!! Need Advise. With the engine off pump the brakes 2-3 times. Then hold pressure on the pedal & start the engine. The pedal should drop a little. Seems like you are not getting vacuum to the booster or the booster is bad. It's not air in the system, that would cause a low pedal. Pull the check valve out of the booster. With the engine off you should get a short sucking noise. When you start the engine ther should be a strong vacuum at the checkvalve & the engine will run rough &/or fast. It's possible you have the adjustment on the rod between the MC & booster too long.