Replaced my Brake Master Cylinder - Now Brake Problems!!!! HELP

Ok, so just some quick history....I have a 2003 Jetta with about 120K miles. Last summer I was noticing about every month or so my brakes would be very hard to depress and I would almost need to STEP on the pedal to get the vehicle to stop. I figured this was because I hadn't changed the brake fluid in the vehicle....ever!
So I then did a complete brake bleed and replaced all the OEM fluid with ATE Super Blue (http://www.ogracing.com/ate-super-blue-brake-fluid) and flushed the whole system using the Motul Power Bleeder (http://www.ecstuning.com/Search/SiteSearch/Power_Bleeder/ES3474/). This didn't seem to make a big difference and the issue seemed to get more frequent when I would have to put a huge portion of my weight on the pedal to get the bakes to respond. It started happening about 1 our of every 10 times I would use the brakes and I started worrying that the brakes would eventually fail.

Just yesterday, I installed a brand new Brake Master Cylinder (http://idparts.com/catalog/product_info.php?products_id=767) from IDParts and again flushed the whole system including the clutch. After doing this, the pedal is less responsive, sometimes sticks (causing the brakes to almost lock up) and again I'm forced to put my whole weight on the pedal to get it to respond. I noticed that when I drive down the road and I initially press on the pedal, there is a "whoosh" sound of what sounds like air, then the brakes start to grab. I would normally think this is air in the lines, but I did bleed them acording to the instructions with the Motul bleeder. I'm REALLY hoping I do not need to replace the Brake Booster along with the master cylinder.

Any thoughts/suggestions?

Have u tried the vaccum pump on off the cam shaft on the right side of the valve cover

Your title is a little miss leading. From what you posted, the problem was there before you ever replaced the master cylinder. You need to stop shotgunning parts at the problem and learn how to diagnose the problem.

It does sound like a vacuum problem. You need a Mighty-Vac to troubleshoot. Your brake booster could need replacing, or you might just have a vacuum leak or faulty tandem pump.

About the "whooshing sound". My 2006 makes what you could describe as a "whooshing sound" inside the cabin at first start up every once and a while and the sound has always stopped after about 10 to15 seconds of running.

Does my booster need replacing? Maybe, but it has made the occasional whoosh for about 2 or 3 years now and the sound has always stopped once vacuum is built up.

How a brake booster works:

http://www.autoshop101.com/forms/brake05.pdf

A great resource for anything you might want to do to your car:

http://www.myturbodiesel.com/1000q/a4/a4-ALH-TDI-engine-index.htm

Rollin-Coal said:

Have u tried the vaccum pump on off the cam shaft on the right side of the valve cover

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OK, you lost me here....I'm not a guru and need some "hand holding". I don't what what this is, where it is and what to look for....???

Any pics or documentation on this?

Ol'Rattler said:

...
It does sound like a vacuum problem. You need a Mighty-Vac to troubleshoot. Your brake booster could need replacing, or you might just have a vacuum leak or faulty tandem pump.

About the "whooshing sound". My 2006 makes what you could describe as a "whooshing sound" inside the cabin at first start up every once and a while and the sound has always stopped after about 10 to15 seconds of running.

Click to expand...

I do have a mighty-vac, but don't know how or what to test it on in the car?
The "whooshing sound" is more specifically like air being expelled when I push down on the pedal and it's heard from inside the cabin. When this happens, there is little if no resistance on the pedal and it actually sticks to the floor and I need to pull it back with my toe.

Also, I don't know if this will help but PRIOR to me replacing the Master Cylinder, when i noticed the pedal getting really hard to press down on, I could rev the RPMs and this seemed to "loosen" up the pedal thus allowing me to then use the brake again under (somewhat) normal conditions....so does this point MORE towards a vacuum problem? Maybe a cracked hose or something?

Sounds like you have a vacuum problem.

There is a hard plastic hose that goes from the vacuum pump onto the brake booster. Check it for leaks. There is a small rubber gasket that sits between the hose and the booster, this gets old and breaks down.

NB_TDi said:

Sounds like you have a vacuum problem.

There is a hard plastic hose that goes from the vacuum pump onto the brake booster. Check it for leaks. There is a small rubber gasket that sits between the hose and the booster, this gets old and breaks down.

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Can someone direct me to where this "vacuum pump" is? thanks

Number 3.

Thank you....I'll take a look at the hoses when I get home!

copatdir6 said:

Also, I don't know if this will help but PRIOR to me replacing the Master Cylinder, when i noticed the pedal getting really hard to press down on, I could rev the RPMs and this seemed to "loosen" up the pedal thus allowing me to then use the brake again under (somewhat) normal conditions....so does this point MORE towards a vacuum problem? Maybe a cracked hose or something?

Click to expand...

Higher RPMS causes the Tandem pump to spin faster so it would create more vacuum which might offset a vacuum leak or dying Tandem pump some.

Sounds like the whoosh sound I experience sometimes, which I think a vacuum leak might well make worse.

The first step would be to make sure the tandem pump is producing vacuum properly and then check the vacuum plumbing and miscalanious vacuum componants for leaks. Go buy a Mityvac. Invaluble for troubleshooting suspected vacuum problems.

http://www.harborfreight.com/mityvac-vacuum-pump-39522.html

copatdir6 said:

The "whooshing sound" is more specifically like air being expelled when I push down on the pedal and it's heard from inside the cabin. When this happens, there is little if no resistance on the pedal and it actually sticks to the floor and I need to pull it back with my toe.

Click to expand...

I'd say that the booster is bad. You should never hear a whoosh of air inside the cabin when pressing the pedal.

When my booster went bad, I got an occasional whoosh that went away when I lightly tapped the pedal. I've read on the site of bad boosters causing your exact symptoms.

RacerTodd said:

I'd say that the booster is bad. You should never hear a whoosh of air inside the cabin when pressing the pedal.

When my booster went bad, I got an occasional whoosh that went away when I lightly tapped the pedal. I've read on the site of bad boosters causing your exact symptoms.

Click to expand...

CRAP!

Well, I did check the cable/hose that goes from the vacuum pump to the booster and it LOOKS fine but the car is currently at a local mechanic's because it needed ball joints replaced and a few other things. He's looking it over and I'm sure I'll have the bad news once he gets into it later today.

OK, update. Mechanic says it's the brake booster. He did find something of an issue with the vacuum pump/lines but fixed that and the booster is still allowing the pedal to stick.

Good news is that I found a used booster about 1.5 hrs away from me on eBay for $40 rather than buying a brand new one for over $300. I'll just need to find a way to go get it this weekend.