What are symptoms of a bad brake booster? (nt)

[BillWilliams]

(nt)

[rho]

Never experienced one, sorry. I'm thinking one that allows fluid to be sucked into the intake manifold causing exhaust smoke is not a 'good' one.

I'm wondering to now that you ask

[DavidLMM]

I think a rock-hard pedal. More here...

http://www.aa1car.com/library/pwrsteer.htm

David

[DavidLMM]

From another site...http://www.carcare.org/Brakes/booster.shtml

"Symptoms of brake booster problems include excessive brake pedal effort, a rough running engine, excessive idle speed, or a whooshing or hissing noise. "

David

[wegweiser]

I just replaced one on the orange project car, because when the check valve was installed properly - the brake pedal would get SUCKED to the floor when pushed even slightly - and have to be manually pulled back up. A working replacement booster solved the problem. I can give you tips on swapping one without cracking brake fluid lines...but it's a bit tricky. e mail me brother!

I think the "bad" one had a frozen / rusted diaphragm return spring.

other failure modes - for E39 5 series - they fill up with WATER! In the winter - the water freezes...guess what happens first thing on a cold February morning as the owner pulls out of the garage! Yikes!

HTH!

Paul

[BillWilliams]

When I redid P2, I used the booster that was in it. I am suffering from a brake pedal that goes 1"-2" before the brakes begin to grab, a high idle, rough running motor and a slight whoosh on start up.

I posted this on my blog:

"First drive around the block - still needs dialed in. Surprisingly I did nothing to the motor and it runs like crap.

The brakes are still soft after power bleeding and pumping, more later."

On a couple of other posts I mention my high idle problem. Took me too long to think about the booster. I hope that is the problem.

Oh, I need a good tii brake booster.

Now Paul, you get to be a genius, tell me how to replace it. e-mal sent

Dave - do you really clean glass with 0000 steel wool?

[Schweineback]

[G.Rice]

engine will stumble even quit when brakes are firmly pressed

[Harv]

I have had all the symptoms listed above.

The most pronounced was the "light touch and have to pull the brake pedal back up" one.

I wonder if there is still some air in your system since the travel seems to be a lot.

Hmmm......

John

[no-id]

I just replaced one on the orange project car, because when the check valve was installed properly - the brake pedal would get SUCKED to the floor when pushed even slightly - and have to be manually pulled back up. A working replacement booster solved the problem. I can give you tips on swapping one without cracking brake fluid lines...but it's a bit tricky. e mail me brother!

I think the "bad" one had a frozen / rusted diaphragm return spring.

other failure modes - for E39 5 series - they fill up with WATER! In the winter - the water freezes...guess what happens first thing on a cold February morning as the owner pulls out of the garage! Yikes!

HTH!

Paul

This could be futile, but i’ll try anyways. WEGEISER, you had mentioned you have a way of swapping the booster without undoing the brake lines. If you happen to be subscribed to this post, would you mind giving me some pointers on how to do this with out cracking the brake lines?

Here is my email address: phoenix1030 at gmail dot com

Thanks!

[TobyB]

Everyone's right, more or less.

When the booster itself fails, usually the diaphragm breaks, and

then you get the really hard pedal. And a huge vacuum leak.

If the car's idling badly, and pulling the booster line and plugging the

manifold fixes it, that's usually what's happened.

When the booster VALVE fails (it's really part of the booster,

but it's separate in function) you can get the hard pedal above,

but without the leak. Or you get a touchy brake pedal (when the spring

in the valve fails) or one that doesn't return. Or you can get a

'brakes locked on' condition where the booster just won't let go!

The fix for everything above is- 'change the booster',

Fluid in the booster's actually a master cylinder failure.

fwiw,

t

[mtriple]

I thought my brakes were just weak the way it is until I swapped my booster. The stocker son of a gun developed an internal leak from the MC and I had a nice quart of brake fluid aging inside the booster.

The difference in braking now is night and day!

GL

Hamada