I have a 89 Civic LX sedan and brake pedal goes to the floor...It did it once last year (Last summer) then back to full pressure...Then did it again3 months ago then back to full pressure...Changed the fluid and installed Speed Bleeders and backat full pressure andI thought it was fixed (Bad fluid soI thought)! And now it back to going to the floor and it's not build any pressure even if you pump brakes (So now no brakes)...No fluid leak (reservor still full) sprayed soapy water on all vacuum hoses and no leaks...Anybody else have same problem and how was it fixed? I'm thinking booster?...I did a forum search but came up empty...Thanks for any help...

John...

 

Check all your brake lines and hoses and for fluid leaks. You could also have a leak inside the master cylinder but usually the brake pedal won't go completly to the floor if you have a internal leak in the master. Check the brake drums. If the wheel cylinders are not good, they may leak fluid. You might not even see this fluid leak since it will accumulate inside the drum. I've seen it happen once before and it was the dirtiest drum i've ever seen. Also, check your calipers. If any of the seals inside the calipers/wheel cylinders are broken, when you pump the pedal the pressure will force fluid through the seal. Since the seal is broken, the fluid will go past the seal. The pedal will go straight to the floor because there is no resistance in the brake system. Remember that hydraulic systems are very unforgiving. If there is a leak anywhere, the entire system will not leak since fluid will go wherever there is least resistance.

 

i believe it can either be the m/c or booster, not quite entirely sure, i'll ask my dad tomorrow, he's a brake guru.

 

my guess would be brake booster or the master cylinder. they are pretty comman to start leaking.

 

My guess is that it is the Master Cylinder. If the booster goes, you would still be able to brake - it would just be harder to do so. Of course, if there is a massive leak, the MC level would be steadily decreasing, so all things point to the MC.

 

Check for fluid where the brake pedal meets teh firewall. If there is fluid there, the seal between the master cylinder and the brake booster might be broken. I doubt that the brake booster is teh problem because the function of the brake booster is to make it easier to assist in pushing the brake pedal. There is no fluid inside the brake booster and the brake booster does not use any hydraulic fluid.

 

Agentofdarkness...There is no leaks anywhere...Everything is dry fromMC all the way to both drum brakes...I'll get a new MC and install it this weekend and let you all know what comes of it......If anybody else has a comment please do reply...I'll keep coming back to this thread and checking tillI install new MC...Thanks everyone for your input...

John...

Ps. How long does a MC supposed to last? This civic only has 110K on the clock...It only had 87K whenI bought it3 years ago...

 

My MC failed at 115K miles. Make sure you bench-bleed the MC before installing it.

 

Hey thanks Roto for reminding me...It's been almost 15 years since I replace a MC on a american vehicle...This is my third civic...Iused to have a 87 civic standard (No frills)thena 88 CRX and now the 89 LX sedan... I also have a 84 toy 4x4 extra cab truck with 110k...This will be my first import MC replacement...But I guess it will be the same as the other american made one I did...Thanks again...

 

it's the same, but if you don't bench bleed...well I'm sure you know what happens than. Also I managed to cross thread an MC once...don't do that either.