92: Should a brake booster hold vacuum?
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Elder User
Joined: Aug 2004
Posts: 646
Likes: 3
From: Derbyshire, UK.
92: Should a brake booster hold vacuum?
Hi,
I get the impression my braking isn't as good as it should be. I've changed pad/ shoes all round, master cylinder and front callipers over the past year or so and so started looking at other stuff. I put my vacuum pump/ gauge set on the booster and couldn't get it to hold a vacuum at all - not even a small one so I would assume its u/s? I would expect to be able to hold some vacuum in it - even if it leaks out over time.
The hose from the manifold tee and the booster check valve is fine (unfortunately!)
Thoughts?
Simon
I get the impression my braking isn't as good as it should be. I've changed pad/ shoes all round, master cylinder and front callipers over the past year or so and so started looking at other stuff. I put my vacuum pump/ gauge set on the booster and couldn't get it to hold a vacuum at all - not even a small one so I would assume its u/s? I would expect to be able to hold some vacuum in it - even if it leaks out over time.
The hose from the manifold tee and the booster check valve is fine (unfortunately!)
Thoughts?
Simon
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
It holds vacuum until you step on the brake. Make sure the grommet around the check valve hasn't cracked or broken. If you have soft brakes I wouldnt think the booster would be the problem as it is for making it easier to brake the vehicle. What kind of brake issues are you experiencing?
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
The fact that it doesn't hold vacuum doesn't seem right, but as said, if your booster is going out, your brakes are rock hard. The booster basically amplifies the pressure your foot puts on the pedal to make braking easier, so if it goes out, the pedal is much harder to press.
That being said, Broncos are not known to stop all that well as it is (unless you have squishy brakes).
That being said, Broncos are not known to stop all that well as it is (unless you have squishy brakes).
Senior User
Joined: Sep 2006
Posts: 282
Likes: 0
From: Broken Arrow
when you changed the master did you find any fluid around the rear seal between the master and the booster? I had a booster fail before where it put vacuum on the rear seal of the master causing the booster to fill with brake fluid and the brakes to be squishy as hell. my bronco on the other hand, when the booster on it failed I had to make a fast choice between a honda civic or a ditch.
