Spongy Brakes

[caseycarson]

What is the most common problem when the brakes are super spongy and occasionally go all the way to the floor? I'm not losing any fluid. The car is going to be in the shop next week for a timing belt replacement and other little things. I'm gonna have this brake issue resolved, too. What is the general consensus of what the problem could be?

 

[Taj]

1) Air in the system - easy to fix, bleed the system should take care of it.

2) Worn brake master cylinder seal or scored cylinder wall - if you have a worn seal; fluid is being transfer back and fore within the cylinder. You can replace all the seals. If the cylinder wall is scored, you need to replace cylinder.

Most likely you are in category 2. If the pedal goes all the way down when you apply a constant pressure, you have a small leak within the cylinder. Gradually the pedal goes straight down to the floor and you won't be able to stop your car at all.

 

[nsxtasy]

If you haven't flushed (replaced) the brake fluid within the past year, I would suggest doing that as well (beyond just bleeding)...

 

[caseycarson]

Only had the car 3 months. Going in for bumper to bumper service on Monday.

 

[NSX-Racer]

If you haven't flushed (replaced) the brake fluid within the past year, I would suggest doing that as well (beyond just bleeding)...

...which leads us to reason No 3: Too much water in the fluid - brake fluid is hydrostatic and loves to suck water. That reduces the boiling point and makes the pedal spongy.

 

[titaniumdave]

I second Taj's diagnosis, sounds like a master cylinder to me too.

If that turns out to be the problem, PM, I have one off a '93 in good condition, I am tired of looking at and would be very happy to sell cheap!

 

[Briank]

I vote for 1 and 2. You have air in the system and your master cylinder is shot.