Brakes on a 1999 Chevy Silverado 1/2 ton

I have a Chevy Silverado 1/2 ton with 80K miles on it. The braking on the truck has been getting worse with age. I have recently replaced all the routers and the pads. The brake lines recently rusted out and had to replace them all. After we bleed the brakes lines several times the pedal came up and brakes were the best they have ever been in a long time.

Unfortuntely, over a period of time the pedal has gone “soft” again, and you need to put the brakes almost to the floor to get it to stop. There is no indicatation that there is any leaks. This truck is only used to tow on vacation or going to stores on weekends.

Other than bleeding the brakes again and again, is there something else I should be checking/replacing:?

you probably have some air in the lines. bleed again and repeat, bleed again. you should be fine

Could be a failing master cylinder. Easy check hold your foot on the brake, if it slowly descends master cylinder is bad.

The problem might be with the brake caliper piston seals.

Brake caliper piston seals can leak where they don’t allow brake fluid to escape, but when the brakes are released and when the caliper piston is drawn back into the caliper this causes a slight amount of air to be drawn into the caliper. So you can bleed the brake system all you want, but if the caliper piston seals leak air, you’ll eventually use the brakes enough times where air is drawn into the caliper(s)which causes the brake pedal to sink to the floor.

Tester