Bmac82

I took on a very simple project and have run into an issue. My brake pads were worn down to nothing so I replaced them. Pretty basic job! Now when I unbolted the caliper, I used a c-clamp to push the pistons back. I didn't pinch the lines or anything like that. Just clamped it back, then slide the caliper back over the new pads. NOW, when the car is off, I get a very hard pedal, however when I start the car, it becomes pretty soft and there's a strange noise every time I press the pedal. It sounds like a leak and air is being pushed out. Not sure how a leak would've happened. No visual leaking, fluid is full. I can't understand whats going on.

dawson1112

Gernerally new brakes need some time to seat against the rotors ,especially if you used the old rotors. Another thing is that as brakes wear out the pistons get closer to there end of travel, this draws more fluid into the caliper and out of the reservoir. If the brake pads wear to far the master cylinder may suck some air into it. You either need to give them a bit to seat to the rotor or you need to bleed the air out of the system. That swoosh or air sound you hear is the vacuum booster and its likely that you have air in the master cylinder

Bmac82

So bleeding the brakes should take care of the problem?

petrock

Bleeding the brakes would be the first step. Good luck...

uberstang1

I would try bleeding the breaks as well, never heard of pads having to "seat"

petrock

If the rotors are worn and have grooves in them, the pads will only ride on the high spots of those grooves. So it will take a little while for the pads to wear into the grooves in the rotor to make 100% contact with the rotor. Thats the seating he’s talking about.

Stevo86

If your brake rotors have grooves in them and you don't have them resurfaced when you do a brake job you should be slapped....Hard. But yeah man bleed the brakes starting with the wheel furthest away from the master cylinder and working towards it.

If you have been driving around with air in the lines and the pedal is now squishy I would get a large bottle of brake fluid and bleed the rears until the fluid looks fresh and bubble free then do the same to the front. Basically a manual brake flush to be sure there are no bubbles left in there. Next time you do a brake job remember to bleed the brakes. It's a good practice to always do it whether or not you open the system.

But you should always open the system when you compress the caliper anyway, the seals in the master cylinder were only meant to hold pressure one direction. Leaving the bleeder screw closed when you compress the piston can damage the seals. This is where someone is going to say but I've done that my whole life blah blah blah...don't care please don't tell me that. It may not always result in damage but it is cutting corners and poor practice if only because brake fluid should be changed periodically anyway.

petrock

It all depends on how deep they are. If the grooves make your rotor look like a vinyl record, which is typical, then you don’t need to do anything to the rotor but the pads will still bed in a little. But I agree if the grooves are deep, then the rotors should be turned or replaced. Just sayin’...