Help: Sinking Brakes

[chosen1]

Need some help folks. I have a civic that has a sinking brake pedal. I changed the brake booster and master cylinder thinking they were the issue. I bled the brakes, I am no seeing any leaking fluid anywhere.

I drove the car yesterday and the pedal bottomed out and did not come back up, had barely any hand brakes..

My next move is to open the rear drums and see if there is leaking inside of them. Baring that, are there any other things I can look at... This car is my daily and I need to get it back in the road.

Any assistance is appreciated..

[Sundar]

Checked the calipers if the piston sticking.

[chosen1]

Thanks

[hong kong phooey]

Are you loosing fluid in the reservoir
Does this car have abs ?

[chosen1]

No abs, no loss of fluid

[kamakazi]

Couple of things
Is the fluid in the reservoir going down by itself and have you had a chance to check the drum brakes.
Also when you say you replaced the master cylinder and booster is that with new units.... Could have stated with just the master cylinder rubbers.
I am also thinking that the system might not be bolted up properly but that is is a bit far-fetched

[chosen1]

The fluid in the reservoir is not going down..Will have to pay more attention to it though. Will be checking the drums either today or tomorrow.

FU booster but brand new MC. I wanted to eliminate these early in the game, even though there was a cost associated.

I inspected the rear drums visually this morning, and I am thinking I may have some leakage. I felt behind the drums and I found dust stuck on and while it wasn't wet, it felt a bit moist.

[hong kong phooey]

If you not loosing fluid then i dont think you have any leaks
try bleeding your brakes again ?
Are you smelling like your brakes rubbing /pistons stuck ?

[wagonrunner]

with the engine off, pump your brake pedal and hold it.
does it go down then?

[chosen1]

Yes...@ wagonrunner, that's exactly what happens.

[wagonrunner]

with the engine off, you either have a leak, one of your lines swells or you got a bad master cylinder

[The Unknown]

And what is the cause of hard pedal but barely any brakes and no leaks
Btw its a ck2 lancer

[HONDA spoilboy]

By chance you changed the booster hose?
Hard peddle sounds like the booster hose leaking or stuck valve .

[chosen1]

I plan to replace the valve...But I will check the booster hose, as I have not as yet

[chosen1]

Well to think of it, I am.not having a hard pedal...

[The Unknown]

But i am lol

[The Unknown]

Im jus stormin ur post for a lil info on mine lol

[chosen1]

When I opened the one drum I found this:

[chosen1]

[kamakazi]

Yep... That would be the cause of the problem.....
Replacement rubbers might be easy to source... But you have to inspect the cylinder and pistons in the drum to make sure the surfaces are not damaged as the rubbers will quickly wear out if they are

[chosen1]

The intent is to replace as much as I can..So I have a new set of shoes and new cylinders to install over the weekend

[kamakazi]

Did you get a chance to check both sides.... Usually when one side fails the other isn't far behind...

[chosen1]

Will replace the cylinders and shoes on both sides..I don't want to have to worry about going back in once I button them up.

[chosen1]

Shoes replaced, brake cylinders replaced, bleed valves replaced, drum covers repainted. Will bleed and test over the weekend. Fingers crossed.

[chosen1]

Well well...after replacing the cylinders, shoes, even bleed valves in the rear brakes the pedal still sinks to the floor.

Bled the rear brakes and was disappointed when the pedal still reacted they way it did. So now it's onto the front brakes... Since I know the rears are good.

Pulled down the front driver side only to realize that the caliper was stuck. When I tried to push it back it did not move until I opened the bleed screw. The slide pins were dry also. I am thinking that I will replace the rubber brake line as well as it looked like the original piece and may be broken down on the inside... Will post more when I button it back up later this week.

[The Unknown]

Ur booster is bad
I had the same exact problem

[chosen1]

I'm hoping it's not as I was getting this problem before I changed the booster recently..

I will service the two fronts and if I still get the problem.. I will change the booster again...it would suck knowing that I replaced a bad booster with a bad one though... But at least I will have confidence in my brakes.

[The Unknown]

Tru

[chosen1]

update

Well i've had no improvement.

After servicing all four brakes, the pedal still sinks. Checked the check valve and vacuum line from the booster to the intake. No leaks. the funny thing is that i can stand on the pedal with the ignition off and as soon as i strart the car the brake pedal gets soft under-foot and sinks to the floor.

There is vacuum in the system, as i hear the air enter if i break the line between the valve and the booster (the check valve is not connected directly unto the booster)

The MC is a new one, the booster is fu...suggestions??

[Dave]

Sinking pedal is loss of pressure. The booster makes the pedal soft not hard. Seems there is a pressure problem.