96 Tahoe Spongy Brake Pedal

[78mc-bbc]

So the brake lines on my 96 Tahoe rotted away and i had to replace every piece of them. After getting all of the lines replaced along with new calipers, pads, wheel cylinders, drums were replaced before i got the Tahoe, and the rubber lines also. so after spending several hours bleeding the brakes my pedal is still pretty spongy, the ABS light is not on, but the brake light is on. When i bleed the brakes i used both a vacuum pump to pull the fluid and also tried the old pumping brake pedal method. when i was replacing the lines i did have the lines removed for a week or two, we had rain here for two weeks straight and the trucks outside.

What do you think my next step should be??

[SunlitComet]

Did your Master cylinder get contaminated too?

[sumo]

my 89 is like that. Ive done everything like you did. Even got a new Mc. 2 even because i thought the 1st one was defective. Next step for me is to get new Rear drum hardware, Springs and ajusters. They are too far corroded to be adjusted. I bet your in the same boat.

[99Yuk]

Open lines being exposed to rain for two weeks straight?
I think that you have water in the line somewhere, not air.

Like air, water will compress under pressure giving you the 'spongy' feel.

My suggestion FWIW, is a complete fluid flush.

I would suggest buying a different color brake fluid, then use the vacumn sucker to flush the lines until you see the new color fluid comming through. I used blue racing fluid, simply for the color. :)

I'd start with the furthest wheel from the master cylnder, the passenger rear wheel, then move closer to the MC ending with the drivers front wheel.

While flushing the lines, stop every couple of minutes to verify the fluid level in the MC. When I did mine, I never let the fluid level drop below 50%.

Good luck!

[bowtiefreak]

^^^^this is where I would start

[78mc-bbc]

well after i posted this i went out and checked the truck again, im getting that wooshing sound when i apply the brakes so im thinking the brake booster went out too.

[BluHoe96]

Had the exact same problem happen to my 96 4dr and I let all the fluid leak out of the reservoir all the three times my lines leaked. Two of which was in snow for more than a couple weeks. If you had the hood down then I don't see how too much water can get in the system especially if you kept the MC cover closed.

Did you try bleeding the brakes from the farthest brake from the MC to the closest? This is the method I used. Also, I did the old fashioned method of someone pressing and holding the brake pedal down, while I loosen the bleeder screw, let the fluid out, tighten, then my asst. lifts the pedal. Those steps repeated until the fluid was a steady stream.

[78mc-bbc]

well i replaced the booster, and the brake light went off after a few pump of the pedal. i did have the hood down the entire time the brake system was apart, so i doubt any water got in. The brakes definitely need bled again, since it take alot of pedal to brake. So i bet i have still air in the lines. I think im going to go to my gf's dad shop and have him bleed them and see if he can bleed the abs pump as well.

thanks for the help

[SunlitComet]

humidity in the has probably creeped its way in there so when you thought you got everything out you might still have micro bits of water.

[ChiTahoe]

flush, flush, and flush, when you think you've flushed enough flush once more.