Brake Problem

[rob2006]

Wow where do i start!
I have a
1992 Pontiac Grand Am SE
4 CYL 2.3L SOHC

Ok this started a few days ago, when I start the car up I hear a hissing sound and the brake is being pushed down for me! I started it and looked at the back and the brake lights are on. Ok second of all when I hit the gas it goes away. Soon as i let go, bam the thing starts braking for me. I really want to know whats wrong with this thing. The motor doesn't seem the same either.

[rixGAphx]

Obviously, a very strong squirrel has crawled under the dash, and he just doesn't want you to move the car!



:D :D



Your brakes are 'power brakes', meaning there's a vacuum assist (vacuum created by the intake manifold sucking air) provided by the booster (large-diameter 'can') onto which the brake master cylinder is mounted.

You have a leak in the vac plumbing:
1. At the manifold connection,
2. Along the hose (1/2" black rubber),
3. At the checkvalve (round plastic piece about 1" diameter halfway along the hose),
4. Or within the Booster itself.

Check around under the hood, maybe get an auto-savvy friend to look.
You seem a little new to this.
If the problem isn't immediately recognizable and fixable, DON'T DRIVE!!
Have a 'Mobile Mechanic' come repair it at the present location, or get a tow (AAA really pays for itself when you own a GA :roll2: ).

Good luck.
-Rick

[rob2006]

I just got my license in january of 05 so my dad gave me his old car and i'm scared to ask him about anything cause I don't wnat him 2 blame me. I already got a flat tire and had 2 secretly purchase another one used so he would not no lol. I fear him lol. So is there a little home done remedy i can do or do i have 2 buy this booster thing u speakign of

[mikem220153]

It is highly doubtful that you did anything to cause this problem. This car is 13 years old, It is going to have mechanical breakdowns. I am sure your dad realizes this.

In any case Rick is right. You are having a vacume issue with your power brake system. Most of the repairs, except for the brake booster will be simple (ie replace the vacume hose, replace the check valve....) It will be a little more complicated if it is the booster. Then, you will to contend with space problems because the booster is jammed in tight between the firewall and the master cylinder. But overall, it is not to hard to troubleshoot and repair. Again, like Rick said, get someone with a little more car savvy to help you and you will be able to fix it quickly.

[rob2006]

Ok guys i appreciate your help. The car is still drivable and all except i cant let up the gas unless i wanna get automatic braking lmao ok Um can you guys tell me where this brake booster is like wehre isthe vacume hose and check valve.

[Prospeeder]

i know what u mean, one day my car woulndt start, tell my dad, WHAT THE HELL DID U DO TO IT!!!!!! and it went away on its own...lol, i still to this day dont know why it did that. But anyway, sounds like a vacuum leak, prolyl from ur booster, check that out, u can spray carb cleaner around vacuum areas and if the idle like, changes, then thats ur leak

[rob2006]

Where is this booster located??? Can i get to it from under the hood??

[TheTrader]

here is a suggestion, snap a few pics of under the hood, post them up, and someone can draw on it what you should check....

[rob2006]

All i have is a pic i could find on the internet...

[rixGAphx]

Rob-

I don't know how to mark a photo and repost it.

Your master cylinder (MC) has a reservoir on top that holds the brake fluid. The reservoir is the is the rectangular black plastic thing with a cap on top.
In the photo, the cap and reservoir are directly in front of the driver, about 12" forward of the firewall.
The MC is the cast metal thing, about 9" long, under the reservoir. It has a couple metal tubes coming out of it.

At the front of the MC there is nothing.
The back of the MC is mounted onto a black metal 'can' that's about the size and shape of a large tin of christmas cookies.
That's the Brake Booster, and the back of it is mounted to the firewall.

On the left side of the can as you look at the photo, there is a plastic fitting with a black rubber hose heading toward the engine.
That is the vacuum line.
* * * *
Read my first response.
The Brake Booster MAY be the problem, but so might be the rubber tubing or the check valve. These are simple and cheap to check and replace.
Do NOT automatically assume that the problem is the booster, especially since it's about $75 and takes several hour of EXPERIENCED labor to replace.

I understand you're on a tight budget, but based on your questions and lack of experience IMO you are not yet qualified to perform this work.
It's not rocket science, but it does require skill and experience.
We're talking about your BRAKES, for pete's sake, and your life and the lives of others on the road.

Do NOT drive this car, it is not safe, and several other things could go wrong with the brakes at time.
Your dad will be MUCH more pissed if you have an accident.

My best advice, as the son of a domineering father, is to suck it up and tell him the problem.
Trust me, he knows he gave you a car that is going to have problems. A father's first (and often deeply hidden) reaction is that HE might be responsible for passing a problem to his kid; that might be why he lashes out at you (to cover his own guilt). Hell, he was prolly having a significant problem every two months when HE had it.
Also, he's prolly having a tough time dealing with you becoming a man (all fathers and sons go thru this, you aren't alone; talk to your high school counselor when you get a chance).
Well, enough dime-store psychology.

Maybe you could suggest that the two of you fix the problem this Saturday, as long as he (or a buddy) has adequate experience.

Good luck with both the car and with dad, we're here for you.
-Rick

[rob2006]

LMAO i Dont need a counseling session lmao!!!!! i just wanted 2 no if i could get 21 this without hihs help i will contact some friends who are smart lol b4 i ask him

[cage47]

OK vacuum basics. The vacuum assists the braking action. that means that it is sucking too much. If there is a leak on the manifold side or a crack in the tube then your vacuum would be too low. In this case it would make your brakes actually harder to work. Think of trying to apply the brakes when the car isn't running. So no it is not a problem with the hose or rubber grommett. In actuality it's working too well. When you give it the gas it reduces your vacuum so it lets the brake go back to it's regular position with the spring tension. The only way for the vacuum to be activating your brakes by itself is if there is a leak in the vacuum booster on the driver side. The only fix for this is to replace the booster itself. not a mechanically tough job but a bugger. If it has a bit of rust on it that would cause the bad seal and leak. This is a major safety issue and should be repaired soon. But no this is not something you did. As stated before it's a 13 year old car. You live in Michigan. Don't know if they're as bad as NY but when I lived up there rust from salt in the winter was the bane of any new car owner. that is probably the problem. And that's something that has worn out in time so your father shouldn't btch. If anything he should have fixed it before giving you the car. I've got a 95 now but had a 92 just like yours a few years back with the quad. Don't ya love how they have all that stuff packed in there. It's going to be fun getting the booster out. Definitely a weekend job but not hard. Get a Haynes book on the car first.