No, it's not. Do you have a reading comprehension problem?
Since you went there, lets actually discuss what you said in depth shall we.
If there is no air in the system...
The master cylinder simply displaces brake fluid...if fluid has a place to go, the master cylinder will continue to displace fluid until there is no more places for fluid to go, at which point it will stop moving.
My suggestion was to isolate the master cylinder from the rest of the system.
Considering the fact that in 2 separate posts the OP said the brakes were bled, and that he had a hard pedal as long as the engine was not running.
Could there possibly be air in the system still? Maybe but he would still have a spongy pedal.
PatMc. Yes I have bled the brakes. And yes the bleed holes are on the top. No offense here to the questions as I said I am new to this which I am. I got to where the brakes seem to work without power but when the engine is on the pedal goes to the floor. I hear a swooosh sound when I pump with the engine running.
Every caliper/wheel cylinder will "consume" a certain fluid volume between apply and release. The master cylinder is sized such that this cumulative volume can be displaced with less than 1/4 or so of the pedal stroke.
Since you are trying to be technical, this is technically incorrect. The wheel cylinders and calipers do not "consume" brake fluid. They are cavities that expand as brake material is consumed. The fluid that is displaced (which is very minimal) as you push the brake pedal simply applies pressure to the pistons in the calipers and wheel cylinders. When you release the pedal this pressure is released. If, and only if the the drum brakes are way out of adjustment will there be any large amount of fluid displaced in which case the spring pressure within the drum brake assembly will in turn push that fluid back into the lines and m/c.
Many people over think brake system hydraulic problems. Let's go back to the basics...
^^^ all that is in a perfect world...but the world is not perfect. We have caliper flex, pad compression, brake hose expansion...all which can "consume" more fluid volume under various conditions.
Talk about over thinking!!
None of those events would equate to a pedal going to the floor.
A leak, or air in the system or a master cylinder with bad internal seals will and I covered all 3 of those issues in my comment prior to yours.
One of 2 situations exists...either you do not have the system properly bled and air still exists and is compressing, or your fluid volume requirement in order to actuate one or more wheel hydraulic assemblies is too great.
Once again wrong answer. Ok well half of it could be the right answer. The second part is not even worth mentioning unless someone has gone completely custom and pieced together a brake system with too small of a master cylinder....
There are 3 possible causes for his symptom, Air in the system, a fluid leak some where, or a master cylinder that is leaking internally.
If the problem remains after this, and you have rubber brake hoses...clamp off all of the brake hoses front and rear, then start the engine and see how the pedal feels...should be about like a rock. If it is...we can make a fair assumption that the problem lies downstream of one of the clamps...with the engine running, remove one clamp at a time and see how the pedal reacts. Each time you introduce another corner back into the system...the pedal will have a bit more travel, but not anywhere near the floor. When you find the corner that after unclamping the line causes the pedal to go to the floor, have a helper cycle the pedal while you stare at that caliper and see what is moving too much and why. Between apply and release, you should barely be able to see any movement, if at all...
Where to start? Clamping a rubber brake hose for the purpose of stopping fluid loss during caliper replacement is one thing, (no pressure) trying to use a clamp to stop the fluid under pressure could be very problematic. It "
could" very easily damage the hose with the amount of clamping force needed to restrict flow even if they are reinforced rubber hoses. As for isolating all 4 corners, that's not possible since he only has 3 brake hoses.
The solution I suggested would accomplish the exact same goal other than isolating individual front calipers. If after isolating the master cylinder he were to find it is in fact not bad, he could easily hook up the front brake line and proceed further with testing while the rear is still plugged off. If all checked out there he could then hook up the rear.
I came up with my test solution based off of this response to my question on post #6
It sounds like what you hear when you blow up a balloon. I can pump the brakes and hear the sound repeatedly. I get resistance in the pedal but if I go slow it will go the floor and then no more sound. If I turn the engine off then I get resistance and the pedal does not go to the floor.
Based on the information he gave prior to and more specifically this reply, the
most likely cause for his problem is the master cylinder.
How did I come up with this conclusion? Experience, and knowing exactly how the braking system works with all it's components.
