Power Brake Booster
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
Power Brake Booster
Would a simple vacuum test isolate if the booster is no good? I am attempting to help a friend with a 1979, when the brakes are applied the car is surging. It is acting like when you have a manual trans in gear and the speed is low. She had the calipers changed and I bleed the brakes already.
Anothe question, what condition or sign if a booster is not working.
Anothe question, what condition or sign if a booster is not working.
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
I would think hanging an external vacuum source on the booster and letting it sit for a few and make sure it holds the vacuum would confirm if the diaphragm is in good shape. Do it disconnected from the engine of course.
You may need to go deeper and press and hold the pedal down and retest while holding the pedal down because maybe the leak doesn't show up until the diaphragm is in an extended position?
Remember to hook up the diaphragm and test the brakes good before taking it for a drive, nothing like forgetting to hook the diaphragm backup and experiencing that first non assist braking effort as a surprise.
What happens to the engine with the booster disconnected and the line plugged at the carb with your foot on the break and engine in gear does it still stumble? Remember to hold the pedal tight.
You may need to go deeper and press and hold the pedal down and retest while holding the pedal down because maybe the leak doesn't show up until the diaphragm is in an extended position?
Remember to hook up the diaphragm and test the brakes good before taking it for a drive, nothing like forgetting to hook the diaphragm backup and experiencing that first non assist braking effort as a surprise.
What happens to the engine with the booster disconnected and the line plugged at the carb with your foot on the break and engine in gear does it still stumble? Remember to hold the pedal tight.
