Hello, my dad and I have been trying to get our breaks working on our 1995 GMC Sierra 1500 and we have bled the lines multiple times and have seen no air coming out. There is no break fluid leaks but no matter what we do there is no break pressure once we start the car. Any advice or things to check for? Thank you!

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1995 GMC Sierra K1500 Squishy breaks

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25/07/2022 4:24 pm

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Hello, my dad and I have been trying to get our breaks working on our 1995 GMC Sierra 1500 and we have bled the lines multiple times and have seen no air coming out. There is no break fluid leaks but no matter what we do there is no break pressure once we start the car. Any advice or things to check for?
Thank you!

btwestbrooks

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25/07/2022 5:15 pm

The correct spelling is BRAKES. You truck has ABS brakes and needs to be bled using a specific technique. It's not the same as a vehicle without ABS. Check out some videos on Youtube. Also, the seals in your 27 year old master cylinder are probably shot and it needs replacement.

Doc

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25/07/2022 5:24 pm

Replace the master cylinder, and bleed the brakes following the ABS procedure for the truck. It's OBDI, so you probably don't need a fancy scan tool to do it, but I could be wrong.

The master cylinder can leak internally, sometimes, causing a mushy pedal when the engine is running. The leak might not be bad enough to show until you have both your foot and the engine vacuum boost pushing on the seals. That is A LOT of pressure.

I had a problem with my 1979 Catalina last year with this. It took 4 brake master cylinders to fix the same problem because of terrible quality control. I tried 2 from AutoZone, and an OEM AC Delco one. I finally got one from Advance Auto Parts that didn't get squishy after I started the car and fully bled the brakes.