Something's wrong with my brakes. Help?

  • Thread starter Newai
  • Start date
  • #1
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'92 Chevy Lumina sedan
3.1L engine

They're really soft. They work, but not like brakes in every other vehicle I've ever driven. When I push down, I have to pump a bit to get to a reasonable level of responsiveness. I can hear what sounds like air squeezing out as I pump. I've replaced everything brake-related I can think of: master cylinder, line, calipers, pads. On a related note, the emergency brake has the same effect. Barely puts any pressure on the wheel; a little gas and the car takes off. My mechanic is out of ideas.

Any thoughts what could be up with this car?
 

Answers and Replies

  • #2
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My mechanic is out of ideas.

Maybe you need a new mechanic.

Definitely sounds like a leak. How is your fluid level?
 
  • #3
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Brake fluid is always fine.

My mechanic has always been very good with my car. Every other problem I've ever had he's handled just fine.
 
  • #4
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If fluid level never goes down, then maybe the brakes need to be bled better. Trapped air will make you have to pump your brakes, also.
 
  • #5
895
98
I agree with Ms Music. Sounds like air in the brake lines. Your mechanic should be using the shop manual procedure for your vehicle to bleed the lines. The procedure is different for different vehicles.
 
  • #6
1,031
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Before you help Newai with his brakes, could you please help me with my ripcord. I keep pulling on it but nothing happens.
 
  • #7
895
98
Before you help Newai with his brakes, could you please help me with my ripcord. I keep pulling on it but nothing happens.

Take your pants off and hold them over your head. Hope I'm not too late.
 
  • #8
turbo
Gold Member
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Have you adjusted your rear brakes? You have drums on the rear, I believe, and you can adjust them by backing up at 10-15 mph and hitting the brakes hard. You might have to do this several times. An empty parking lot is probably the best place to do this.
 
  • #9
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Well, we've handled the bleeding very carefully. Though that feels like it's the right area, I believe there's more to it.

No drum brakes at all.

Before you help Newai with his brakes, could you please help me with my ripcord. I keep pulling on it but nothing happens.
My manual strongly suggests placing thumb in mouth and blowing real hard.
 
  • #10
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To Newai and any other interested person, I have a tip for bleeding brakes. Well, if I remember right, that is. See, my dad made me take auto shop to buy a car, and since the boy to girl ratio was unbelievable................ ;) But that experience was also long before your car was made. So I don't remember all the details.

My dad had this contraption that he made, where you take a small jar and fill it part way up with brake fluid. Find a tube that fits the brake bleed valve (wish I remembered the diameter, but you can find that out easily). Tightly clamp one end of the tube on the bleed valve, and stick the other end into the brake fluid. Then slowly pump the brakes numerous times. You can technically bleed brakes all by yourself this way, although it is much quicker with 2 people.

I had brake issues on my car that I drove in high school (68 Cougar XR7) and wound up replacing the entire brake system, piece by piece. I had to do it the "high school auto shop" way, and my dad's way, depending on where I was working on my car. Bleeding works best with my dad's method, as when you take your foot off the break, there is no air sneaking back into the line.

Might be worth a try.
 
  • #11
BobG
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If your car has ABS, then there is definitely a distinct procedure for bleeding the lines, which you have to do if you've replaced the calipers or anything else that opens the lines to air.

It's more complicated than the old non-ABS brakes (and I didn't even like bleeding them, although I was always able to eventually get them bled properly).

Of course, as long as ABS has been around, any good auto shop should be able to bleed an ABS system properly. An experienced home mechanic that relies on his own experience and common sense may have more trouble, but still should be able to bleed the brakes provided he follows the sequence in the manual, etc (it's not that incredibly different than the old brake systems).

The fact that the emergency brake doesn't work well either suggests some other problem or multiple problems, though. Emergency brakes usually rely on cables/levers rather than hydraulic pressure. However, those also have to be adjusted if you replaced your rear brakes.

Edit: Ms Music's method works for non-ABS brakes, but probably won't work for ABS systems.

The real secret is to never open the brake lines. Of course, that's impossible if you replace as many parts as you did.
 
  • #12
27
1
To Newai and any other interested person, I have a tip for bleeding brakes. Well, if I remember right, that is. See, my dad made me take auto shop to buy a car, and since the boy to girl ratio was unbelievable................ ;) But that experience was also long before your car was made. So I don't remember all the details.

My dad had this contraption that he made, where you take a small jar and fill it part way up with brake fluid. Find a tube that fits the brake bleed valve (wish I remembered the diameter, but you can find that out easily). Tightly clamp one end of the tube on the bleed valve, and stick the other end into the brake fluid. Then slowly pump the brakes numerous times. You can technically bleed brakes all by yourself this way, although it is much quicker with 2 people.

I had brake issues on my car that I drove in high school (68 Cougar XR7) and wound up replacing the entire brake system, piece by piece. I had to do it the "high school auto shop" way, and my dad's way, depending on where I was working on my car. Bleeding works best with my dad's method, as when you take your foot off the break, there is no air sneaking back into the line.

Might be worth a try.

That is what we've done.

The car shouldn't have ABS since there's nothing on the brake pedal, and he's gone over everything in the car related to that anyway. I also noticed that there is no ALB fuse in the box, if that helps.
 
  • #13
AlephZero
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Sort the handbrake out first, because you should be able to put the car on a ramp, take the wheels off, and see what is happening (or not happening) when you pull the lever.

If the handbrake is barely operating the brake pads, quite likely the footbrake has a lot of slack for the same reason.
 
  • #14
DaveC426913
Gold Member
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Before you help Newai with his brakes, could you please help me with my ripcord. I keep pulling on it but nothing happens.
:rofl: :rofl:

I always love these 'need diagnosis urgent' threads, but your turn of a phrase is genius!
 
  • #15
1,045
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Sort the handbrake out first, because you should be able to put the car on a ramp, take the wheels off, and see what is happening (or not happening) when you pull the lever.

If the handbrake is barely operating the brake pads, quite likely the footbrake has a lot of slack for the same reason.

The E-brake on those drums is cable driven to a secondary mechanism. The foot-brake feeds an actuator. Unless there is a huge (and loud) mechanical flaw in the horseshoe-shaped apparatus that applies pressure, it's not likely that both of these systems would fail to work. It's a redundant system, with one low-fail part between them.
 
  • #16
869
4
Shot in the dark, but it could be a mis-sized rotor.
 
  • #17
85
166
Anti lock brakes were an option on the 92 Lumina Euro sedan. They have to be bled in the correct sequence or they can do weird things.

Pumping the pedal with ABS isn't a good idea.
 
  • #18
dlgoff
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I can hear what sounds like air squeezing out as I pump.

What you are hearing is the power/boost(assist) vacuum leaking. It's what the master cylinder is attached to. Between your foot and the master cylinder.

http://www.cardone.com/English/Club/Products/Brakes/Protech/Images/930393e.gif
 
  • #19
85
166
What you are hearing is the power/boost(assist) vacuum leaking. It's what the master cylinder is attached to. Between your foot and the master cylinder.

http://www.cardone.com/English/Club/Products/Brakes/Protech/Images/930393e.gif

I think you just nailed it down.:approve:
 
  • #20
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1
Shot in the dark, but it could be a mis-sized rotor.

The rotors are indeed larger than the ones the car came with. That matters?
 
  • #21
BobG
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That is what we've done.

The car shouldn't have ABS since there's nothing on the brake pedal, and he's gone over everything in the car related to that anyway. I also noticed that there is no ALB fuse in the box, if that helps.

Are you sure? ABS is standard on the Euro model, which has a 3.1L engine. ABS is optional on the base model, which has a 2.5L engine.

Not a guarantee, since you can swap out engines and the car is nearly 20 years old, but I think you have the Euro model.

http://www.edmunds.com/chevrolet/lumina/1992/
 
  • #22
27
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Are you sure? ABS is standard on the Euro model, which has a 3.1L engine. ABS is optional on the base model, which has a 2.5L engine.

Not a guarantee, since you can swap out engines and the car is nearly 20 years old, but I think you have the Euro model.

http://www.edmunds.com/chevrolet/lumina/1992/

This car isn't the Euro model. The engine was replaced; I didn't know that the base model was 2.5. Should that be mentioned when I'm getting parts that aren't engine related?
 
  • #23
BobG
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This car isn't the Euro model. The engine was replaced; I didn't know that the base model was 2.5. Should that be mentioned when I'm getting parts that aren't engine related?

Possibly. You wouldn't think the brake rotors would be dependent on engine size, but if you just give the parts store the make and engine size, there's a good chance they'll just automatically give you parts for the Euro model instead of the base model.

And you did say the new rotor isn't the same size as the old.
 
  • #24
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Funny thing about that is the dashboard reads Euro because I replaced that, too. My car is so confused.

Okay, so far it looks like mismatched parts and vacuum booster/hose. Otherwise, the car is in really good shape so it might be worth the money.
 
  • #25
BobG
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I think you've reached the point where your only solution is to call Car Talk.

http://xkcd.com/582/
brakes.png


Note: I have a t-shirt with this cartoon on it. It encompasses two of my favorite things on one t-shirt: Car Talk and xkcd.
 
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