Brake problem

[1979C20]

Okay, I'm having some issues with my brakes. about a month ago, my truck was taking more pedal to stop, and my brake light would come on on my dash. I checked the fluid levels in the master and the reservoir for the rear brakes was low. I topped it back off and the brakes were normal and the light stopped coming on. It starter doing it again last week so I topped off the fluid again and it fixed it again, but now, I'm having some problems. I was driving along and everything was normal. Then I went to stop and when I pressed the pedal it made a loud swoosh sound, like air rushing out. The truck wouldnt even slow down with the normal amount of pressure on the pedal. I have to practically stand on the pedal now for it to stop. I replaced my wheel cylinders a few months back and bled all 4 brakes. Its not leaking anywhere from the brake lines or from any wheel. But, my brake booster is coated in brake fluid. What would be the cause of this? the brake booster, or the master cylinder?

[zieg85]

Master cylinder is leaking.

[1979C20]

So the master cylinder needs to be replaced? and I don't need to worry about the brake booster?

[87454westernhauler]

its the master cylinder.

[1979C20]

Okay, thanks guys. I'll get it swapped out today.

[1980c10]

Then I went to stop and when I pressed the pedal it made a loud swoosh sound, like air rushing out. The truck wouldnt even slow down with the normal amount of pressure on the pedal. I have to practically stand on the pedal now for it to stop.

Like previously said your master cylinder is bad and needs replacing.
When your master cylinder leaks back in to the booster; the brake fluid can eat at the diaphragm inside and cause it to go bad as well. From what I quoted above it sounds like that this may have happened.

[sbx22]

You probably know this already, but don't forget to bench bleed the new master cylinder.

[1979C20]

Okay, looks like I need to replace both then. I had checker order in the brake booster/master cylinder combo last night. Gonna see if my mom will give me the $140 for it because "she doesn't want her son to die because I have no power brakes". I'll see if that works out and if not then I'll have to make a good amount of money the next couple of days.

[1980c10]

Most likely your booster is bad but test it first.
Verify vacuum to the booster from the engine.
With your truck not running put your foot on the brake a couple of times and then while pushing down the brake start the truck. If the booster is good your foot will easily sink the pedal down.
or/and
You can run the engine, shut it off
push the pedal once and it should go down easy 1st time and then hard after that.
or/and
you can use a vacuum pump and see if the booster will hold vacuum.

For anyone else reading this; if you see brake fluid dripping on the booster below the master cylinder replace it as it will save your booster.
Master cylinders are cheap and boosters are not.
I'm replacing my master cylinder this weekend in order to save my booster.

[txchainsawgogi]

i've replaced my master cylinder THREE times now, and each time after a few months it starts to leak and flash rust around the base/sides. however…it feels like my booster works. would air trapped in the lines cause it(the mc) to leak eventually?

[bake74]

i've replaced my master cylinder THREE times now, and each time after a few months it starts to leak and flash rust around the base/sides. however…it feels like my booster works. would air trapped in the lines cause it(the mc) to leak eventually?

     Are you buying re manufactured ones and have they been from the same place ?  Maybe try a different source to buy it if they have all come from the same place.  Air should not make them leak, you are bench bleeding them first I assume.

[1979C20]

My booster is out. I tested it by removing the check valve at the booster. If I did this right after shutting the truck off before, it would suck in air. But now, when I unplug it it doesnt suck in air. So It is not holding vacuum. My mom is going to but it for me today. I'll get it swapped out probably tonight.

[gto109]

quote author=bake74 link=topic=23071.msg191606#msg191606 date=1329396413]

i've replaced my master cylinder THREE times now, and each time after a few months it starts to leak and flash rust around the base/sides. however…it feels like my booster works. would air trapped in the lines cause it(the mc) to leak eventually?

     Are you buying re manufactured ones and have they been from the same place ?  Maybe try a different source to buy it if they have all come from the same place.  Air should not make them leak, you are bench bleeding them first I assume.
[/quote]


I used to work for FenCo a few years ago.  Just so you know they remanufacture master cylinders for all the major parts stores just about and half of them they even rebox with that stores name on it and sell it right beside the FenCo branded ones.

[txchainsawgogi]

so… we shouldnt buy fenco ones?

i've had one new one, and two remans… i think all different(or apparently the same) brands haha.

[gto109]

I'm not sayin to not buy fenco I'm just saying that they package for other places.