master cylinder or brake booster?

Hi,

When you first start the vehicle, do you mean the brake pedal is hard to push? Or does it go to the floor and then pump up?

If it is hard to press, that would likely indicate a vacuum leak to the brake booster. It is common for a plastic nipple that is molded into the connector.

Check for a broken nipple on the vacuum line leading to the brake booster. The brake booster vacuum line is located between the engine and the bulkhead on the left side of the engine compartment, connected to the front of the brake booster unit.

I attached two pics below to help locate and identify if this is the problem.

Let me know what you find or if I am incorrect about what is happening.

Take care,

Joe

See pics below.

Hi Joe,


Thanks for that. when i start the car and push the brake pedal it's a little soft but not completely loose where i can push it easily to the floor. it firms up to "normal" after i give it a few pumps.


i looked at the part you pointed out and took a picture of it. i gently moved the hoses and there's nothing broken on them and there's no leaking around the hoses.


Weldon

P.S.

i my last email i wrote: The master cylinder is much more involved. ....it should read: The brake booster is much more involved.

Hi,

Does it go to the floor? You mentioned it was soft when first started and then firms up when you pump the brakes.

You should have power assist as soon as the engine starts. Is that happening?

Let me know.

Joe

Hi Joe,


The brake pedal doesn't go all the way to the floor, but yes, there is power assist. It gets firmer the more i pump the brakes.

W

Hi,

Do me a favor. It's difficult to determine where the issue is because if it doesn't go to the floor, it sounds like the master cylinder is good. If you have power assist, that appears to be working. So, here is what I want you to try. Pump the brakes so you get a good brake pedal and then hold pressure on it. If there is a leak or issue with the Master Cylinder, the pedal may slowly drop to the floor.

Let me know if that happens.

Take care,

Joe

hi Joe,


ok. started the car and the brake pedal has pressure. it doesn't go to the floor. when i hold pressure to the brake it maintains most of the pressure but recedes a little. it doesn't go to the floor.


W

Hi,

If the brake master cylinder was the issue, I would have expected it to slowly drop to the floor. However, I still need to better understand something. When you say you need to wait for a bit and when pumping the brakes, they eventually come to life, what exactly happens that gives you that feeling? Do you start getting power assist?

Joe

hi Joe,


if i start the car when it is cold and put it in drive the car moves slowly forward. i push on the brake pedal and the brakes work but you can tell they are very weak. what i usually do then is put the car in park, pump the brakes and after about 6 pumps the brakes grab normally. what i usually do is just to let the car run for a bit while in park and then push on the brake pedal.

are you thinking it might just be a faulty Brake Power Booster Unit Check Valve?

Hi,

If the brake pedal is stiff at first and then becomes easier to press, yes. It sounds like the booster. However, if it is easy to push the entire time and they don't work at first and there is no change in the brake pedal resistance, then I think it's something different.

Let me know.

Joe