Muddy looking brake fluid

[HBlue]

My 76 C10 brakes went out Friday. The pedal goes all the way to the floor with very little stopping power.

I pulled the cover off and found the fluid a little low, and it has a muddy look to it. I had the calipers, brake shoes and one brake line replaced a couple of months ago.

Do I need to replace the master cylinder or power booster or both?

Should I bleed out all of the old fluid and replace with new?

This truck was driven only about 1000 miles over the last 4 years. I just bought it in January.

[andrewmp6]

I'd try replacing the fluid first if its no different then booster/master or both.

[geezer#99]

Check the rear drums for cylinder leaks. New rear shoes put the piston's in the cylinder in a different spot. If the cylinder bore isn't clean you'll get leaks along with a bit of brake dust drawn into the cylinder.

[old Rusty C10]

fluid swap to start then inspect everything else real well

[HBlue]

The price of a new master cylinder was reasonable, so I decided to replace it and all the contaminated looking fluid.

The brakes are fine now.

[macpro1965]

Brake fluid will absorb moisture over time, I drain mine when I restore/restomod trucks then if I keep them long enough I usually change the brake fluid every 2 years.