Hello everyone,

I have a '96 360, 4x4 with rear anti lock brakes. When I step on the brake it doesn't start having any effect until about halfway down and then I have to stand on it. Also, when there is a air sucking sound when the brake pedel is pushed to the floor and held. Using the search function on this forum, it's sounding like the vacuum booster. but the sound is not coming from in front of me. It sounds like it's coming from somewhere near my feet. I'm still leaning towards the vacuum booster though.

Mac

 

Before buying a new brake booster, I would do the following:

- check your brake fluid level
- may need to bleed brakes to see if air is in the lines

The above two are the only explaination I can think of as to why nothing happens until you are halfway down the brake pedal. If both of these turn out ok:

- Check the connections and the line itself for the vacuum linegoing from the intake manifold to the brake booster

If everything checks out up to this point, then you probably have a leak inside your booster. The sound could still be coming from your feet, it just depends on where the leak is located. At this point, I would replace the booster. Just remember when you bleed the brakes, make sure you do it with the engine running and the booster active otherwise the brakes will probably have a mushy feel..

 

Just another thought... the check valve in the booster vac line may be leaking???
WC

 

Thanks for the help guys. I've settled on the vacuum booster. Ipulled the vacuum line to the booster,looked atthe check valveand the rubber grommet for leaks,then tried the brakes. The brakes were not mushy. Also, I crawled up underneath the dash to observe and listen to brakes. As soon as I push on the brakes, even a little, Ihear a vacuum sucking sound.

Thanks again,

Scott

 

Yes, you should not be hearing any air noise under normal braking.
So I would point to the booster too.

 

check the health of your pads and rotors/shoes and drums?

 

I changed the pads a few months ago and the shoes last week. I was doing a visual of the brake system last week as part of trouble shooting when I saw the shoes were almost down to the rivets. Not too bad for 136,000 miles. I also bled the rear brakes.

Shott8283, Semper Fi from a fellow Marine.

Mac

 

FYI. I changed out the vacuum booster and problem solved. Thanks for the help guys.