Do You Need to Bleed Brakes After Replacing Brake Pads?

Unless you opened a brake line or bleeder valve you do not have to bleed brakes after replacing brake pads

Since you didn’t open any brake lines, there’s not chance you got air into the system, so there’s no need to bleed your brakes after replacing brake pads. However, there are good reasons to bleed the brake fluid out of the brake caliper as you compress the caliper piston

Why remove brake fluid during a brake pad change

All brake fluid absorbs moisture and when the water content reaches 3-4%, that water can reduce braking efficiency. It can also cause internal corrosion. Once corrosion forms in the braking system, it settles in the lowest portion fo the system, which is in your brake calipers.

If you just compress the piston without bleeding off the fluid, you can force any corrosion crud backwards and up into the ABS valves. That can clog the valves causing big issues, including having to replace the ABS valve assembly, which is very expensive.

How to bleed brake fluid when replacing brake pads

Purchase a few feet of 1/4″ diameter vinyl hose from any auto parts store.
Slide a box end wrench over the bleeder screw and then install the hose onto the bleeder screw
Connect the other end of the hose into a jar.
Crack open the bleeder screw as you start compressing the caliper piston into the caliper bore. That will push the contaminated fluid out and into the jar.
Right before the caliper piston hits bottom, close off the bleeder screw. This will prevent air from getting into the system.

In general, if you’re only replacing the brake pads and have not opened or tampered with the hydraulic system, you do not need to bleed the brakes. However, if there’s any doubt about the integrity of the braking system or if there’s any indication that air might have entered the brake lines, then bleeding is a wise precaution. Safety should always be the top priority, and ensuring your brakes are in optimal working condition is critical for both the driver and other road users.

© , 2023 Rick Muscoplat

Posted on September 13, 2023 by Rick Muscoplat