How To Fix a Spongy Brake Pedal Chevy Truck

In truth, this is a video about how to replace and bleed a master cylinder on a C1500, 1990 5.7L to be specific. However, I do have information on how you can solve a spongy brake pedal on one of these trucks by replacing the master cylinder and booster with parts from a later model truck.

Here are those part #’s

Master Cylinder: M390259

Booster: 5471046

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Due to factors beyond the control of EricTheCarGuy, it cannot guarantee against unauthorized modifications of this information, or improper use of this information.  EricTheCarGuy assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. EricTheCarGuy recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video.  Due to factors beyond the control of EricTheCarGuy, no information contained in this video shall create any express or implied warranty or guarantee of any particular result.  Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not EricTheCarGuy®.


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45 thoughts on “How To Fix a Spongy Brake Pedal Chevy Truck

  1. i've had to do more master cylinders on chevy trucks than i even want to think about…..a little trick i have done to get the air out of the lines is,i will take a front and rear wheel off,and have someone push the caliper piston back in with a c clamp while i loosen the line at the master cylinder. i do bench bleed the master with brass fitings and clear tubing before hand.

  2. I fixed my soft pedal by changing the cap on the master cylinder reservoir, I do have a question, you pump the brake pedal to bleed the brakes, but its difficult on a power brake system,when the cars not running theres no pressure??? a mechanic friend told me put small clear hoses on all four bleeder screws and open them all then and have them drain in a pan or jar filled with some brake fluid and let gravity do the rest eventually the air will push out,sort of like when you siphon

  3. I replaced two rear wheel cylinders on 91 Ford Ranger. I've tried all the bleeding tricks and I still have a spongy brake. Solution? Take it to a brake shop.

  4. Great vedeo i do exactly on my 95suburban but the brake pedal loose pressure!! When I press the brake pedal he going to end and not keep pressure!! And not leaking brake fluid anywhere! I tried many times and not have a normal pressure on brake pedal!! Anybody knows what's wrong 😕 thanks fellas

  5. I have an 06. And what was causing my sponginess was that i had the front and rear ports criss crossed between the abs module and the master cylinder. Took forever to figure that one out.

  6. Excellent video. The easy way to fix a brake issue. Easy step by step instructions on this to keep from having issues later with the brakes , great video. Thanks

  7. hi erik i have a 79 camaro and when i press the break pedal it sounds like air is leaking n ita harder to break the more i drive do i have to replace the whole booster?🙏

  8. I use a pressure bleeder, needing 2 people to bleed brakes is a waste of time to slow and doesn't always get all the air out, Time is money. Why any professional tech wouldn't invest in a pressure bleeder is beyond me

  9. Hi Eric O without bench bleeding the brakes can't work or bc I have been bleeding same brake the whole day but still the brake is not working please for your advice thanks

  10. I replaced my master cyl. In my 01 1500 express adj. Rears bleed all the lines, replaced both calipers with ceramic pads, still have soft pedal, i cant figure out why?

  11. I'm 42 yrs old. Have done all my own work forever and never had to replace a master cylinder.
    Great process. Nice explanations. Thanks!

  12. I'm watching this video because I have bled all four calipers twice but still I'm getting a spongy feel when the engine is running. Pedal is solid after a few pumps when engine is off though. Where could the problem be?

  13. So it didn't work??? I watched the whole damn thing and it didn't work??? Misleading title. Should have said "Trying to fix spongy break pedal…FAIL"

  14. I was taught to put short brake lines from the ports back into the reservoir and pump till the bubbles stop. It's always worked for without most of the mess.

  15. I'm honestly curious what your feelings are about vacuum booster vs hydroboost? My current truck is hydroboost and it's the first ever I owned. I like it but that's subjective at best.

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