# Brake pedal goes to floor even after replacing master cylinder



## madarua (Sep 10, 2007)

Okay, so I searched through previous posts concerning the symptoms of my braking system, and all said the same thing, that the master cylinder is bad. However, I just replaced my MC and the same symptoms are still occurring.
The pedal will go to the floor, repeated pumping doesn't seem to help/bring up pressure. There are no leaks, I've bled 2 quarts of fluid through the system and don't see any more bubbles coming through.
What is going on? It's driving me insane. Anyone run into this before? If it helps, it's a MKII Scirocco.


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## teutoned (Jul 29, 2008)

*Re: Brake pedal goes to floor even after replacing master cylinder (madarua)*

your post doesn't state if you bench bled master before install?


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## madarua (Sep 10, 2007)

*Re: Brake pedal goes to floor even after replacing master cylinder (teutoned)*

Would not having bench bled it first really make that big of an impact?


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## teutoned (Jul 29, 2008)

*Re: Brake pedal goes to floor even after replacing master cylinder (madarua)*

yes!







first bleed system at master by cracking rear line at master and depress pedal, close line, repeat a few times, then do w/ front line at master. then proceed to each corner of vehicle.


_Modified by teutoned at 3:57 PM 2-27-2009_


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## madarua (Sep 10, 2007)

*Re: Brake pedal goes to floor even after replacing master cylinder (teutoned)*

Didn't have time to mess with it for a few days... 
Anyhow, so I bench bled, rebled the brake lines... Not really any noticeable change, pedal's still going to the floor, no air's coming out of the lines. 
I suspect that my new master cylinder might be the issue.







A friend and I noticed that it makes a slight popping noise, as though a seal's rolling on itself or something, when the piston goes about halfway.
I'll try it again with another one, and chances are things will be fine. So annoying...


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## madarua (Sep 10, 2007)

*Re: Brake pedal goes to floor even after replacing master cylinder (teutoned)*

Right, so... I'm still pretty baffled. So are several of my local car buddies that I've explained the situation to.








Bench bled the master cylinder to try this again with, that was fine. Discovered that one of my rear calipers had seized, which definitely wasn't helping matters, but got that resolved. Hooked up the master, bled through a ton of fluid... pedal still goes to the floor.
Now, my friend in charge of pumping the pedal said that it got pretty stiff-feeling as I was doing the rears... but the moment I started on the fronts, back to the floor it went, and it hasn't improved, even with bleeding through the lines a second time. 
Is there some sort of trick I'm missing? I mean, it's a simple system... booster, MC, lines, two proportioning valves, and the calipers. But I've never had trouble like this on another vehicle.


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## FrigginE (Dec 6, 2008)

Did anyone ever figure this out? I'm having a similar problem with my mk.2 GTI


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## GTijoejoe (Oct 6, 2001)

*Re: Brake pedal goes to floor even after replacing master cylinder (madarua)*


_Quote, originally posted by *madarua* »_Right, so... I'm still pretty baffled. So are several of my local car buddies that I've explained the situation to.








Bench bled the master cylinder to try this again with, that was fine. Discovered that one of my rear calipers had seized, which definitely wasn't helping matters, but got that resolved. Hooked up the master, bled through a ton of fluid... pedal still goes to the floor.
Now, my friend in charge of pumping the pedal said that it got pretty stiff-feeling as I was doing the rears... but the moment I started on the fronts, back to the floor it went, and it hasn't improved, even with bleeding through the lines a second time. 
Is there some sort of trick I'm missing? I mean, it's a simple system... booster, MC, lines, two proportioning valves, and the calipers. But I've never had trouble like this on another vehicle.









If all caliper ports are closed, does the pedal go to the floor? 
If the pedal is not stiff, are you losing any fluid?
You can unbolt the calipers from the carriers and put some wood in there and bleed them, tap them with a rubber hammer to shake any small air bubbles to the top.
Or you can try a vaccum bleeder. 
When you bench bleed the MC, if the out ports are closed/sealed, the pistons should basically be locked, if it is not, than the MC seals are leaking.


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## vw-gti_1987 (Mar 4, 2008)

*Re: Brake pedal goes to floor even after replacing master cylinder (madarua)*

So a couple months ago I had this same thing happen to my gti. I purchased a new oem mk2 mc and put probably 2 quarts of fluid through the system but the pedal still went to the floor. I then lubbed all the slide pins and made sure all the calipers weren't leaking. I then decided to try another mc went to a local parts place and bought a new mk3 mc. I spent probably 4 hours chasing a stupid problem that shouldn't have even happened just because of faulty parts. Oh and if you want to save some cash and time bench bleed the mc for sure. I guess that's my .02, return the mc and buy your self a mk3 mc.


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## EuroMKII (Mar 2, 2008)

*Re: Brake pedal goes to floor even after replacing master cylinder (vw-gti_1987)*

Ok, may be a stupid question here, but I have seen it before (when I changed out my firts master cylinder). Did you get the push rod back on for the master cylinder? Not questioning your intelligence, just know that the first m/c I replaced (way back when) on my MKII, the rod fell off of the the plunger in the booster. I must have screwed with that thing for a week before I figured it out. The rod fell in to the booster. Just a thought, hope this helps.


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## FrigginE (Dec 6, 2008)

I just picked up a MC out of a junked mk3 Jetta. It says 22 on the side and looks to be a bit fatter than the one I have on there now. Hopefully this will do the trick.


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## jk35 (Sep 1, 2008)

*Re: (FrigginE)*

You know, I'm the King of DIY, and I'm always encouraging others to try to do things for themselves too. We all love cars, and most find great satisfaction in working on , maintaining, modding and the like.
BUT! It's obvious many of you have no business servicing your own brakes!
This basic automotive system is THE most important one. Without it your car is uncontrollable! (Unstoppable! some would say, and not in a good way, either!)
Improperly installed/bled/bedded in, you increase your chances of KILLING yourself and others. You don't want to be involved or responsible for a MDK, do you? 
(murder-death-kill)
LEARN everything you should know, learn it proficiently and provide the utmost care and attention to detail when working on systems as important as BRAKES.
If you find yourself on here asking questions about simple operations like this, that's a pretty good sign that you should either:
A. take your car to someone competent and certified for such procedures
B. At least take the time to educate yourself proficiently
I have never wrote anything like this, but I have also never read anything like this thread!
Enough ass-chewing, hopefully you get the point...
Now, I thought I might suggest speed bleeders. They are cheap, and they make bleeding out your system so easy it's scary. You'll use a small pipe wrench to remove your existing frozen bleeder screws, screw in the speed bleeders and follow the instructions from the back of the SpeedBleeders' blister pack. (2 mini pipe wrenches are indispensable for working on brake lines/brake systems, as even flare nut wrenches can and often DO round off fittings/heads. 
While you're at it, Find someone with the same car/size and pick up an additional pair to split with them. As Speed Bleeders work equally well on clutch systems.
http://www.speedbleeder.com/au...s.htm


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## madarua (Sep 10, 2007)

*Re: (jk35)*

Thank you brake patrol.
It's hard to kill anybody with a car that I wouldn't drive, since the brakes weren't working, thank you.








Now, I tried many methods of bleeding, including a speed bleeder and pressure bleeding, none of which helped. Turned out that the calipers I upgraded to from a B3 passat were rather touchy about air, and at the same time were abnormally good at getting air stuck in them, requiring me to take them off the vehicle and turn them -just- right for the air to come out. So annoying.
But please, don't question competency for this. The brake system on an '86 Scirocco is fairly simple, and I do know the ins and outs of it. Especially now. That's why it becomes frustrating when things don't go as they would. I've done brake systems before on other vehicles, and I've never had one behave like this, but hey, you learn as you go.
As for reading anything like this thread... They're all over if you check through the search. I read them all in my search for info.


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## chknkatsu (Jun 19, 2008)

*Re: Brake pedal goes to floor even after replacing master cylinder (madarua)*

all aboard







the fail boat


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