Brake Problem!!

[bigal0043]

alright so i was driving home last night from school and the brakes went completely soft.. like went to the floor... but i could pump them to get pressure... after i got it pumped to stiff again i held it in to see if i was losing pressure but wasnt... it only seems to loose pressure when i dont use it and after like 15 mins of driving.. it is fine before everything seems to get warmed up...

but it happened again when i was in the city but on the way to work... on the highway getting off the exit..

and once it lost pressure u have to pump it for the rest of the time in the car till the car cools down... any ideas?? i was thinking an air pocket maybe???

the brake pads are pretty thick so its not that and it is not losing brake fluid it is completely full..

 

[Nick M]

Sounds like there is a small leak, which has caused air to get into the lines. If you had a bad master cylinder, the pedal would sink when you were holding it, and you said it didnt.

 

[bigal0043]

hmm where do u think the leak would be?

that is why i tested to see if the pedal would sink...

 

[rakkasan]

hmm where do u think the leak would be?

that is why i tested to see if the pedal would sink...

the easy way to find it is to have someone pump up your brakes while you look for the leak, it should be obvious due to the amount of pressure hydrolic brakes build.

 

[psifactor]

So when you pump it really fast its fine but when you go to press it slowly it goes right to the floor? It may just be the master cyl going bad. I had one with those symptions.

You could also just have a small leak somewhere else in the system.

 

[bigal0043]

well sort of.. after i dont use the brakes for a little bit it will get real spongy again.. when i pump it i can get full pressure again...

yea wouldnt that mean i would be leaking brake fluid though??


cuz it is still full

also why would it do it when it is just warm?? is it because it flows better thus leaking better?

 

[psifactor]

If you are not losing any fluid it probably is the master cyl.

They are like $58 bucks and $35 dollar core charge and its pretty simple to change.

 

[bigal0043]

alright ill check tonight

 

[bigal0043]

Alright ill update everyone... there was an option for an wideband on my turbo elbow and it fell out... must not have been tight... but anyway that was blowing the exhaust air right on my brake lines causing it to boil my brake fluid... So my problem is fixed now...

 

[mrnickleye]

Better do a complete fluid change on those brakes. The fluid is now bad, since it boiled. This is a task you can do with a friend to push the peddle while you bleed out the old fluid.

Get a qt. of Dot 3 fluid, a 12" piece of vacuum line, and a clear bottle (coke?).
Top up the fluid in the master, and never let it get too low (air into the system will be hell to bleed out).

Using a box wrench (8mm I think), crack loose the right rear bleed screw (its the furthest away from the master cyl) and then put the vacuum hose over the screw while the wrench is still on it. Place the other end into the bottle. Have friend press down and hold the brake pedal. He should yell "down" when he's all the way down. Now you snug (tighten) the bleed screw, then say "up", so friend lets pedal up.

Repeat this process EXACTLY 3-5X. Fluid will be brown at first, then clear looking as new fluid has made it thru the lines. Tighten (but not too much) the screw, then go to other rear caliper and repeat the process. Make sure to top up master between each caliper bleeding. Then do right front, and finally left front.

Empty coke bottle after each caliper bleed. Be very careful, as brake fluid is so caustic, it will blind your eyes, and eat you car paint right off !!!

This method will ensure that air does not get into lines. Top up master and replace cap.

 

[bigal0043]

alright ill do this.. .this weekand