Dirty Master Cylinder and Fluid

DixieWASP · Apr 21, 2023

Yesterday I couldn’t get my 1989 Silverado’s master cylinder to bleed. It appears to be original and the brake fluid had probably never been flushed. I have a new MC but didn’t get it installed today.

I am including some pictures of the old master cylinder.

JOHNGAAA1 · Apr 26, 2023

Change it. If that crud is in the master the inside of the lines are probably just as bad.

Erik the Awful · Apr 27, 2023

I'm a cheapskate. If you're not having any problems, bleed your brakes with good fluid and run it. Sure, there will be sediment in your lines, but you're not going to get that sediment out without replacing the lines.

Reluctanse · Apr 27, 2023

You could also take the MC off and bench bleed it until all clear, then reinstall it and give a good bleed to follow.

I just did mine and made a huge difference in pedal feel.

DixieWASP · Apr 27, 2023

I purchased an AC Delco master cylinder from Amazon and installed it Monday. I made sure I flushed all the old and dirty brake fluid out of the system.

Supercharged111 · Apr 27, 2023

Erik the Awful said:
I'm a cheapskate. If you're not having any problems, bleed your brakes with good fluid and run it. Sure, there will be sediment in your lines, but you're not going to get that sediment out without replacing the lines.

Same. I would have wiped the crud out of that master, bled it, and slept like a baby.

Schurkey · Apr 28, 2023

Supercharged111 said:
Same. I would have wiped the crud out of that master, bled it, and slept like a baby.

That's my standard operating procedure. Otherwise I'd be replacing every master cylinder on every vehicle I work on.

The problem children are the dumbass master cylinder designs where you can't get inside the reservoir to wipe it out, because the cap is too small.

Caman96 · Apr 28, 2023

I’ll probably rebuild my MC when the time comes. I see a lot of bad reviews on new Acdelco/Raysbestos MC’s leaking within a year.

grampadirt · Apr 28, 2023

I just installed a Centric MC,replacing an old Centric which lasted almost ten years before it started leaking out the rear.

Dirty Master Cylinder and Fluid

DixieWASP

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