nfm

Hey guys,

Car progressively has been braking worse and brake pedal was hissing when braking. Pads and fluid has been changed. I thought the hissing is do to the brake booster, sound was coming from the pushrod that connects to the brake pedal. I just finished installing another brake booster and results are terrible :

Thanks to google, video lost all of its brightness.
http://www.youtube.com/watch?v=Ya5kGh8GlLM

I can't feel pressure at all now air seems to be leaking from pushrod or somewhere around that area. Also with car off the pedal won't build up any pressure. Please help .

gotkilled

iTrader: (1)

did you make sure all the bubbles are out of the brake system and that there is brake fluid up to the max line in the reservoir? also, did you tighten each of the, for lack of a better word, caps on the calipers that allow the fluid to come out.

01tl4tl

the only order for brake bleeding-flushing is as follows:
start at driver front wheel- if brembo brakes (6 speed manual trans cars),
do the outer bleeder nipple first till no bubbles and clean fluid, then inner bleeder
(regular TL same order but only has 1 bleeder for front calipers)
refill master cyl after each caliper is bled- dont let it get empty!!
now passenger side front- same as left side procedure
next passenger rear
then last driver rear
LF RF RR LR
anything else mucks up the system- its due to the ABS plumbing

there is a known problem with abs system and air- talk to your service manager- give them cars VIN and they can look up if part of affected cars
can result in many braking issues

I hate cars

Can you be a little more descriptive?

Is the pedal hard? Do the brakes work at all? Does it go all the way to the floor? Does the hissing stop when the engine is off? Did you have to remove any brake lines when replacing the booster or could you slide the master off without disconnecting anything?

Answer those questions and you will narrow it down to another bad booster or a bad master.

Generally if the pedal is going all the way to the floor it's not the booster, it's serious air in the lines, bad caliper, or bad master. With the cover off of the reservior, does it try and shoot fluid back out or blow air bubbles out when you hit the pedal?

There was also a known bad ABS actuator for certain TLs. There is a listing of VIN numbers affected somewhere around here.

solpolanco

Is the hissing sound like air compressing or escaping? If it is escaping like a long hiss and the sound is as loud to you with the windows up as it is with them down start with simple solutions before you think the worst. It might be the rubber seal on your brake cap is worn or is beginning to flutter under pressure. This is not the solution just a suggestion. If the only problem is noise and not performance take your time, and walk through the mechanical working stages of each component while someone pushes down on your brake. If it is a rubbing kind of hiss like your pad on always engaging your rotor check your rubber hosing on your brake lines. Again I don’t have an answer but I read what you wrote and sometimes having someone just take the time out to care helps out enough to clear your head and make everything fall into place smoother. Let us know what it was when you get a chance

nfm

Brakes do not work at all.Yes the pedal goes all the way down, with car on pedal sounds like loud vacuum and it's very soft.Yes the hissing stops, pedal won't build any pressure. The brake pedal feels like a stiff clutch.Yes the brake lines were removed from the master cylinder and I had to catch some fluid that was coming out.

I think that I might be having just serious air in the lines as you said. I did not bleed the lines after brake booster install. I simply poured fluid back to the master cylinder and reservoir, at least those were the procedures in the service manual pages. The troubleshooting pages within Acura TL service manual pointed to bad brake booster from the beginning.

How should I bleed the brakes now since what it appears is that pedal isn't building any pressure?

I hate cars

I've only got a minute so I will get into more detail when I get back. When you disconnect the lines you should "Bench bleed" the master. I do it the complete wrong way but it's always worked. I have someone sit in the car and push the pedal while I have my thumbs over the holes. When the person lets up on the pedal the thumbs act as a check valve to keep air from getting in. Do this a couple times and get the lines back in as quick as possible. I have the person on the car very slowly pushing down on the pedal as I'm screwing in the brake lines to help keep air out of the master. After this you have to do a complete system bleed. Buy a couple bottles of fluid and follow the factory bleeding procedure.

Don't forget to go out and hit ABS a few times once the bleeding is complete and rebleed. Sorry for being so vague but I'll be back later.

nfm

Thanks for all of the help so far folks.

I benched the master cylinder, bled all of the lines and got rid of lots of air. With car off the pedal builds pressure now. I checked the "check valve/one-way valve" that connects from brake booster to the engine and it works properly. However the hiss is still there , but with pedal pressed all they way down it stops (shouldn't it be the other way?), it's coming from the pushrod, and it's actually vacuum:
http://www.youtube.com/watch?v=qWFFxOpbPHw
(notice how rubber get sucked in when I press on it)
Could it be that the replacement booster is a lemon too? What could make the diaphragm from the pedal side leak in such a way?