96 Tahoe Spongy Brake Pedal

78mc-bbc · May 30, 2011

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 · May 31, 2011

Did your Master cylinder get contaminated too?

sumo · May 31, 2011

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 · May 31, 2011

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 · May 31, 2011

^^^^this is where I would start

78mc-bbc · Jun 2, 2011

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 · Jun 7, 2011

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 · Jun 7, 2011

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 · Jun 7, 2011

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 · Jun 8, 2011

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

lou4LSU · Jun 28, 2015

brake fluid is hydroscopic (I believe that's the right word) but it will absorb water if u put a cup of water and a cup of brake fluid next to each other over night the water will be gone the next day due to the brake fluid taking it in. im having a similar problem with my 96 4dr 4wd. pedal is soft and you can hear a woosh when you quickly press it. pedal goes about halfway before I get a decent reaction and can be pressed all the way to the floor without much reaction unless going slow. just replaced all pads and shoes but problem was there before but seems worse now. going to do a full flush but any ideas are welcome.

SunlitComet · Jun 28, 2015

properly adjust the rear shoe adjusters. check for bulging rubber brake lines. get the abs system cycled a few times to see if the issue changes. some would say that the whoosh you hear is the complication of the issue going over ones head but it it the air movement in the vacuum brake booster and it is normal to hear it.

96 Tahoe Spongy Brake Pedal

78mc-bbc

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SunlitComet

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sumo

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99Yuk

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bowtiefreak

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78mc-bbc

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BluHoe96

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78mc-bbc

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SunlitComet

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ChiTahoe

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lou4LSU

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SunlitComet

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