Hi,
Have a 93' Econoline 250HD. Replaced my own brake pads on the two front wheels, when I was done during first drive the pedal went to the floor with probably half of braking available. Tried to bleed brakes but nothing. Is it possible that changing pads on 104K mile truck damaged my master cylinder?

Thank for Help.

 

should not have. did you look for fluid leaks in the flex lines? does it work better if you "pump" them up?

It kinda sounds like air. Any possibility you uncovered the hole in the MC during the operation?

 

Mustang 5.0,

Thanks for responding. I don't see any brake fluid anywhere, I bled the front brakes yesterday, about 4' of fluid in the bleed tube on each, but no help.

The brake does get stronger when pumping, but I can always push it to the floor with strong pressure.

 

Does sound like air in the system, or a MC that is leaking past the orings internally.

I"d bleed them some more (brake fluid is inexpensive). both the front and the rears.

If you accidently got air into the system (at the MC) its in both the front and the rears. If you changed calipers (you didn't say) then its probably in the front onlyl

If this doesn't cure it, then the MC would be my next suspect.

Thnk over the job. what exactly did you do when you changed the pads? was the MC full at all times? any caliper work? flex line replacement? rear brake work?

I've got a road trip and will be oot. bbl

 

If you hold steady pressure on the pedal, and it slowly goes to the floor, that is an indication of an internal master cylinder leak.

It's possible when bleeding the brakes, when the cylinder bottomed out, there is some trash or corrosion in the bore, that is now causing the internal leak.

You're probably gonna have to replace the m/cylinder.

 

Agree on the trash in the MC. I put a 2x4 under the brake pedal to keep me from bottoming the MC and doing just that with the trash. Never lost a MC yet.

 

Definately sounds like air in the system. . I would re-bleed all 4 wheels. Also, Im assuming you are experienced in the proper bleeding techniques (& your helper too if your doing it the old fashioned way) and making sure to keep the master full at all times. ...I would also check ALL lines for leaks, mabye you created a new leak that wasnt there before you changed the pads. Dont forget to check the rear wheel cylinders too. ....Once all air is out & no leaks found then its surely your master cylinder.