having problems with my brakes. The pedal goes down to the floor and the car
is very hard to stop. I replaced the master cylinder and still the same
thing. I'm wondering if the vacuum booster is going bad due to the fact that
I sometimes hear which sounds like air coming from behind the dashboard when
applying brakes. I checked the line itself, the engine speed decreases when
I put my finger over the hose. I'm also wondering if it might still be some
air in the brake lines?
If you didn't bleed the brakes until bubbles and clean fluid came out after
the master cyl. change, air is a good suspect. I hope you are using some
type of service manual for the work. It should tell you the proper way to
bleed brakes. I always invert a fresh bottle of fluid in the master cyl.
and then bleed the right rear first. I used to flush brakes every coulpe of
years to be sure moisture isn't a problem.
A "whoosh" when hitting the brakes is normal, there is a rubber bellows on
the lever at the firewall. The vacuum side of things is under the hood.
Even if the brake booster had no vacuum, the pedal wouldn't go to the floor.
It would be very hard to puch right from the start but it would be solid.
What led you to replace the master cyl. to begin with?
So it would seem the problem remained after the change. Hmmm... I expect
you have checked for leakage so we can bypass tube replacement and such.
I found that any time I had a soft pedal, flushing the system usually fixed
it. It is the same as bleeding the brakes, just more of it. Bleeding works
best with a helper unless you have a machine to help. Always do the
furthest wheel first. On this car, I would do the right rear, then left
rear. Right front, then the left front. Be sure the fluid doesn't get low
in the master cyl. I think I mentioned earlier, I invert a fresh bottle of
DOT3 in the proper chamber before starting.
I had a car not too long ago that had frozen rear pistons. It was drum
brakes on the rear and a new assembly for each side was quite cheap. That
made a huge difference in stopping but the pedal never went soft or hit the
I am running out of ideas here - I think better when I am staring at the
machine in question - . Bleed / flush the brake lines would be the next
step for me...
Found out the problem. There was still air in the system and I also had to
replace a leaking brake line and heat up the bleeder valves on the rear
drums to get them off.
Thanks everyone for their help and suggestions.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.