chenxuwen

All four brakes locked up

9 posts in this topic

Dear All,

Could you help me diagnose a brake problem?

My rear brakes are burning red hot and cooking brake pads, so I changed rear calipers, pads, and rotors. Then I was to bleed all four brakes yesterday. Then the following happen.

Note: 1. all the wheels can be turned freely before turning on the car. 2. The car has no abs

1. Start the engine.

2. Bleed rear passenger side. Fluid came out very, pressure not enough, not very much fluid coming out.

3. Bleed rear driver side. Fluid came out slowly, pressure not enoguh, not very much fluid coming out.

4. Bleed front passenger side. Fluid eject for a second, but only air coming out. No matter how many time I try, only fluid with buble burst out for a short period, cannot maintain pressure.

5. Bleed front driver side. Fluid eject for a second, but only air coming out. No matter how many time I try, only fluid with buble burst out for a short period, cannot maintain pressure.

6. Fully confused and realized that all four wheels cannot be turned or are all locked up.

7. During the front brakes bleeding process, the pedal can be easily pressed to the ground.

8. One hour after turn off the car, wheels can be turned now.

Could you help me diagnose this brake problem?

Thanks a lot!

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I recommend opening the bleeder valves and let gravity bleed them first. Once fluid starts coming out on their own. Then start the manual bleeding process. You have to keep doing this till you see no more air bubbles in the system and the brake pedal no longer spongy. Keep the reservoir topped off and don't let air in. You may need several bottles of brake fluid to do this.

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I thought you were supposed to have the engine off when you bleed the brakes? That's how I've always done it, but I don't know for sure.

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Never heard of bleeding brakes with the engine running lol.

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18 hours ago, Tiberianx said:

Never heard of bleeding brakes with the engine running lol.

Maybe I am doing it wrong. I learned that from a bad mechanic then...

Anyway, already bought brake booster and master cylinder. I will bleed with engine off this time.

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A symptom of a failing brake booster is a hard to depress brake pedal. You have to push very hard for the car to stop.

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35 minutes ago, Tiberianx said:

A symptom of a failing brake booster is a hard to depress brake pedal. You have to push very hard for the car to stop.

I got another symtom: once brake is pressed, the engine idles rough. Without it, it idles fine. So I assume the brake booster affected the engine and should be replaced. Am I having the right logic?

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I would presume that you would also have braking issues first in addition to the vacuum leak from the booster. Especially if you were to push the pedal down, you would hear a whoosh noise like air escaping from the brake pedal area meaning air escaping from the brake booster. Although I would be optimistic of the possibility of it having a vacuum leak and causing rough idle.

 

When you push the brake pedal, the brake lights puts a load on your alternator. If you hold the brakes, does all your lights flicker? If you turn on all your loads or some of it like a.c., dome lights, high beam; does your engine buckle?

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8 minutes ago, Tiberianx said:

I would presume that you would also have braking issues first in addition to the vacuum leak from the booster. Especially if you were to push the pedal down, you would hear a whoosh noise like air escaping from the brake pedal area meaning air escaping from the brake booster. Although I would be optimistic of the possibility of it having a vacuum leak and causing rough idle.

 

When you push the brake pedal, the brake lights puts a load on your alternator. If you hold the brakes, does all your lights flicker? If you turn on all your loads or some of it like a.c., dome lights, high beam; does your engine buckle?

Yes, you are right, there is a choose sound whenever I press the brake. Without pressing the brake, one can have everything on.

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