2003 Blazer, about 85k miles. Proud owner since '05. With engine running, therefore power booster in use, a strong brake application brings the "crook" on the shaft, behind the pedal, down almost touching the carpet. The system has been bled several times over, both by me and my local shop (The owner, a friend of mine, has always said he'd rather push a Chevy than drive a Ford).

There are no leaks, no fluid loss. The vehicle does stop ok, but I don't remember if it was always like this or not.

So, my question is, how far does your pedal go down with a firm application? I have no problem with replacing the master, but I'd like some idea if mine is abnormal.

 

that's a tough question to answer. Is the pedal soft or spongy? Does it start hard and then soft and then hard? Is it hard all the time?

 

It is possible that the master cylinder has air in it or that the internal seals are worn causing some fluid to not be compressed.

 

I was hoping someone would reply with some info re my original question- how close to the floor does your pedal arm go upon a firm application with the engine running (and therefore, power boost supplied)?

 

Mine stops about 2/3 of the way thru the swing. So what you are describing is definitely considered to be excessive pedal travel. I am sorry I did not mean to bypass that portion of the question. And to answer what you are probably now thinking yes that is very big safety issue.

 

If you push the pedal and it keeps on creeping down then the MC is leaking internally and needs to be replaced.

 

Thanks, that's what I was looking for. I had in mind to replace the cyl but not if the long travel of mine was normal. As far as the safety issue- the pedal goes down so far that, once or twice, my big sasquatch foot has caught the edge of the gas pedal at the same time. Very exciting!