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Discussion Starter · #1 ·
2002, 1.8t manual. 213,000 miles. PCV system was throwing a P0171 system too lean code, found the breather hose below the PCV valve was blown open. Replaced the PCV breather hose, the suction jet pump, and also replaced the 07C 133 529 A valve too. System too lean codes have NOT returned since.

I'm having brake problems. The problems started before I replaced the hose and valves. Initially, the problem presented itself like this: on cold starts, the brake pedal would sometimes get stuck in the applied position. Turning the car off and on would sometimes allow the pedal to 'pop' back up.

Lately, the problem has gotten worse. If I leave the car sit (in below freezing temps - it's winter here) for more than a day or two, I will come out to a ROCK-HARD brake pedal. Can't push it at all. If I limp it into work (I work at a car dealership) I can park it inside the shop for a few hours and the pedal will release upon warming up.

On cold days where the pedal is not frozen on a cold start, I can get about 25 travel on the brake pedal, and then the rest of the travel is very stiff - like I can't push the pedal down all the way.

My last few driving trips, the STOP Brake Fault warning message has flashed on my display, with the brake indicator on my dash flashing. Every time it it occurs, it's when I'm decelerating, and braking, while making a right turn. Tapping the brakes in each instance has made the message go away. This might mean my pads have worn to the indicators, right? I will check the pad thickness when we pull the wheels off today.

I have the car on the hoist today, and we're going to drain the brake fluid and replace it, to rule out any water accumulation in the brake system that might have been causing it to freeze.

Besides valves 07C 133 529 A and 058 133 753 B, what other check valves should I be concerned with in the brake system. I've read that the brake booster rarely if ever fails. What other concerns should I be looking at?

Thanks in advance...
 

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Discussion Starter · #3 ·
Check all the caliper slider pins to ensure they are not seized. 2 pins per caliper.
I thought you might mention that. We'll check them. That topic has been brought up too. What's the best way to free these slider pins if they're sticking? Silicone spray? Something else?
 

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It's not the slide pins. That leads to brakes being applied continuously without using the pedal. (But FYI, cleaning them is really easy; pull the calipers, remove the pins, clean with brake cleaner, inspect (replace if worn), grease with brake lube (no other kind of lube!), re-insert.)

Sounds to me like you have a bad brake booster; maybe water got in it? That would explain the freezing, and the pedal going hard on you.

If the problem was the pads, you'd get a brake wear warning light. A blinking "STOP BRAKE FAULT" is something else entirely. A scan with VCDS might reveal what issues the brakes are reporting.
 

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Discussion Starter · #5 ·
Car's on the lift, nothing serious to report mechanically. Normal pad/rotor wear, all calipers, guide pins, pistons appear to be moving properly. We're going to flush the brake fluid (just because it's not a bad idea) and I'm going to look into codes with my VAGCOM.

If the brake booster has water in it, how do we fix that? Can the water be removed?
 

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Car's on the lift, nothing serious to report mechanically. Normal pad/rotor wear, all calipers, guide pins, pistons appear to be moving properly. We're going to flush the brake fluid (just because it's not a bad idea) and I'm going to look into codes with my VAGCOM.

If the brake booster has water in it, how do we fix that? Can the water be removed?
I'm not a brake expert, but I'm pretty sure the booster is not something you can disassemble and fix. It likely needs to be replaced.

Of course, before replacing such an expensive part, ask the mechanics at the dealership. The brake system on the B5 isn't different from any other car. Certainly they have somebody there that can give you a hand with diagnosis.
 

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Discussion Starter · #7 ·
I'm not a brake expert, but I'm pretty sure the booster is not something you can disassemble and fix. It likely needs to be replaced.
Nah, I did some reading, and it looks like you can siphon out water by going in through the vacuum line opening. I found this info in a Google Search:

2002 vw passat: water in the brake booster..liter..service center

Resolved Question:
I evidently have water in the brake booster of my 2002 vw passat 1.8 liter. There was a service bulliten on the issue but service center doesnt want to give up the fix it info. I'm mechanically inclined and want to fix myself. It sounds like a simply vaccum tube issue. Obviously this is just an issue when its cold (20 degrees for extended period) but it's annoying none the less. Can you help? Thnks Tom from WV


Submitted: 5 years ago.

vwtech0405
Expert: vwtech0405 replied 5 years ago.
Ok the issue with water getting into your brake booster is because water gets under the wiper cowl wich the water will gather up and go into the booster because the drains are clogged there are 2 rubber drains one is located below the battery tray and there is another one located right under the brake booster what we usually do here at the shop is remove the drain completely so it will not get clogged again i recommend you do the same. I hope this helps. You might also find leaves from tress you make sure the drains are not clogged or blocked. I hope this helps.

Customer: replied 5 years ago.
Sounds good...but what happens to the water already in the booster... does it go away..evaporate, etc..?



vwtech0405
Expert: vwtech0405 replied 5 years ago.
What we do is remove the water by using siphon tool that will remove the water from the booster.


Customer: replied 5 years ago.
I just assumed that the inside of the booster wasn't accessible? How do you access? thnks


Expert: vwtech0405 replied 5 years ago.
There is a hose that goes right in the front of it into remove the hose then you will be able to get the water out of it.
vwtech0405, VW Technician
 

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Discussion Starter · #8 ·
So we dipped a stick in the vacuum hole for the brake booster and found water. Hooked up the siphoning machine and was AMAZED at the amount of water we pulled out.

We're going to let it sit with the vacuum hose pulled off for an overnight and let it air out.

Also found the positive terminal was severely corroded and when we finally broke the battery harness free from it, we noticed that there was a bulge around the positive terminal. Looks like the battery froze at some point. It's under warranty, so we're going to replace that too.
 

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Well, you learn something new every day. Didn't know you could suck water out of a booster and have it work afterwards; I would have thought the freezing would have broken some vital bit of plastic, rendering the booster broken.
 

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Discussion Starter · #10 ·
Found some more information on the NHTCA website - apparently the issue is constrained to model year 2002 alone:


NHTSA Action Number : PE07018 NHTSA Recall Campaign Number : N/A
Vehicle Make / Model: Model Year(s):
VOLKSWAGEN / PASSAT 2002
Manufacturer(s) :
Volkswagen Group of America, Inc.
Component(s) :
SERVICE BRAKES, HYDRAULIC: POWER ASSIST:VACUUM
Date Investigation Opened : April 3, 2007
Date Investigation Closed : September 4, 2007
Summary:
DURING THIS INVESTIGATION, VOLKSWAGEN OF AMERICA (VW) IDENTIFIED A PROBLEM WITH WATER ACCUMULATION IN THE FRESH AIR PLENUM THAT COULD, IN CERTAIN CIRCUMSTANCES, RESULT IN REDUCED BRAKE POWER ASSIST IN MODEL YEAR (MY) 2002 PASSAT VEHICLES. VW INDICATED THAT PROBLEM IS CAUSED BY LEAVES AND OTHER DEBRIS CLOGGING THE PLENUM DRAINS, WHICH MAY RESULT IN WATER FILLING THE PLENUM TO THE LEVEL OF THE BRAKE BOOSTER AIR INTAKE. THE BOOSTER AIR INTAKE IS LOCATED IN THE FRESH AIR PLENUM IN THE MY 2002 PASSAT VEHICLES, BUT NOT IN THE MY 2001 OR 2003 VEHICLES WHICH DRAW BOOSTER AIR FROM THE CABIN. VW TESTING SHOWED THAT BRAKE ASSIST COULD BE REDUCED IF WATER ENTERS THE BOOSTER AND FREEZES. VW IS ADDRESSING THE PROBLEM WITH A SERVICE CAMPAIGN, WHICH BEGAN IN AUGUST 2007. THE FRESH AIR PLENUM IN THE SUBJECT VEHICLES IS AN ENCLOSED SPACE AT THE BASE OF THE WINDSHIELD FROM WHICH THE VEHICLE VENTILATION SYSTEM DRAWS THE FRESH AIR SUPPLY VIA A POLLEN FILTER. RAIN WATER THAT FLOWS OFF THE WINDSHIELD INTO THE PLENUM IS DRAINED THROUGH TWO VALVES LOCATED BELOW THE BATTERY AND BRAKE BOOSTER. STRAINERS AT THE BASE OF THE WINDSHIELD AND IN THE PANEL COVERING THE TOP OF THE PLENUM BLOCK LEAVES, PINE NEEDLES AND OTHER DEBRIS. OVER TIME, DEBRIS MAY ENTER THE PLENUM THROUGH OPENINGS IN THE PLENUM PANEL OR AROUND THE HOOD HINGES. IF CLOGGED DRAINS ALLOW APPROXIMATELY 3-4 GALLONS OF WATER TO ACCUMULATE IN THE PLENUM, THE WATER MAY ENTER THE BOOSTER THROUGH THE AIR INTAKE. WATER ACCUMULATION IN THE PLENUM MAY ALSO RESULT IN COMPLAINTS OF WET CARPETS IN THE VEHICLE INTERIOR IF THE WATER REACHES THE LEVEL OF THE FRESH AIR INTAKE/POLLEN FILTER. VW STATED THAT ITS TESTING SHOWED THAT BRAKE PERFORMANCE AND ACTUATING FORCE (I.E., PEDAL EFFORT) ARE NOT AFFECTED WHEN THE BOOSTER IS FILLED WITH THE MAXIMUM AMOUNT OF WATER POSSIBLE (UP TO THE HEIGHT OF THE BOOSTER ENGINE VACUUM CONNECTION, THROUGH WHICH WATER DRAWN INTO THE BOOSTER IS EVACUATED). VW'S TESTING SHOWED THAT BRAKE PERFORMANCE AND ACTUATING FORCE COULD BE AFFECTED BY WATER FREEZING IN THE BOOSTER. HOWEVER, WHEN TESTED WITH RELATIVELY LOW VOLUMES OF FROZEN WATER IN THE BOOSTER, VW SHOWED THAT THE EFFECTS WERE SIGNIFICANTLY LESS SEVERE THAN FOR CONDITIONS THAT RESULT IN A COMPLETE LOSS OF VACUUM ASSIST. WHILE VW INDICATED THAT THE EFFECTS WOULD BE MORE SEVERE WITH GREATER VOLUMES OF FROZEN WATER, IT MAINTAINED THAT THE CHANCES OF THIS OCCURRING WERE REMOTE AND WOULD BE READILY DISCERNABLE TO THE DRIVER UPON THE INITIAL BRAKE APPLICATION AFTER VEHICLE START-UP. ODI'S ANALYSIS OF COMPLAINTS AND WARRANTY DATA SHOWED DISPROPORTIONATE CONCENTRATIONS IN WINTER MONTHS AND IN NORTHERN STATES WITH COLDER WINTER CLIMATES. ODI IDENTIFIED THREE MINOR CRASHES RELATED TO THE ALLEGED DEFECT IN MY 2002 PASSAT VEHICLES. TWO OF THE CRASHES OCCURRED IN GARAGES/DRIVEWAYS AND THE THIRD OCCURRED IN A DEALER SERVICE GARAGE. THERE WERE NO INJURIES ALLEGED IN THE CRASHES BUT A FOOT INJURY WAS ALLEGED IN A FOURTH INCIDENT WHERE EXCESSIVE BRAKE EFFORT REQUIRED DURING A HARD STOP. VOLKSWAGEN IS CONDUCTING A SERVICE CAMPAIGN TO REMEDY THIS CONDITION IN MY 2002 PASSAT AND AUDI A4 AND A6 VEHICLES. THE REMEDY PROCEDURE REQUIRES VW DEALERS TO INSPECT, CLEAN AND MODIFY THE AIR PLENUM DRAIN, AS WELL AS MODIFY THE SUNROOF DRAIN (IF EQUIPPED) AND INSTALL AN IMPROVED SEAL FOR THE POLLEN FILTER. IN ADDITION, VW HAS AGREED TO PROVIDE THE FOLLOWING INFORMATION TO ODI 1. QUARTERLY COMPLETION REPORTS FOR ONE YEAR; AND 2. PROMPTLY REPORTING ALL CRASHES ATTRIBUTED TO THE ALLEGED DEFECT. THIS INVESTIGATION IS CLOSED BASED UPON THE ACTIONS TAKEN BY VW. THE CLOSING OF THIS INVESTIGATION DOES NOT CONSTITUTE A FINDING BY NHTSA THAT A SAFETY-RELATED DEFECT DOES NOT EXIST. THE AGENCY WILL CONTINUE TO MONITOR COMPLAINTS AND INFORMATION VW IS REQUIRED TO SUBMIT RELATING TO THE ALLEGED DEFECT IN THE SUBJECT VEHICLES AND TAKE FURTHER ACTION IN THE FUTURE IF WARRANTED.
 

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Well, make sure you report your particular incident to the NHTSA so it can get logged.
 

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Discussion Starter · #13 ·
Normal brake function has returned, however I can still feel the brake booster rod sticking when I extend it by pressing the brake pedal more than about 75%....so I'm guessing there's some rust on the brake booster rod. Normal braking does not cause the pedal to stick, but during a hard stop I can get the rod to stick, causing my pedal to not return properly. I can snap the pedal back by pulling on it with my feet, however.

I'm going to drive it normally for a while and see if the pedal travel during normal driving slowly works the rod clean. I'll try random hard stops to try and work the rod clean as well.

If it continues to get worse, I'll try spraying some penetrating oil in there and see if it helps.

I'll probably be looking at a new booster if I can't get it sliding freely again.

I wonder how long the water was in there.....
 

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You should contact VW being sure to mention the recall above and see if they will replace the booster. I don't think life safety items have an expiration.
 

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Discussion Starter · #15 ·
You should contact VW being sure to mention the recall above and see if they will replace the booster. I don't think life safety items have an expiration.
I don't think a recall was ever issued with that NHTSA action. That's why the recall number says 'N/A.'

But I personally feel this is a safety concern, and there should be a recall action on this.
 

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Well, if you do get it fixed and a recall is issued later, you will get reimbursed for the earlier repair.

I wouldn't hold my breath waiting for a recall. Even for a safety-related problem, if it hasn't been recalled in the last dozen years, it probably isn't going to get recalled now. At some point, safety-related item failure just gets tallied as wear-and-tear. For instance, every brake caliper ever made has rebuild kits available because sometimes the pistons blow. Every one has rebuilt MC's stocked because sometimes the the bores get scratched up.

If it were my car, I would go ahead and replace the booster instead of trying to repair it. Certainly you don't want to boil your fluid one day because a slightly sticky booster roasts melts the seals on all four calipers, boils your brake fluid, kills your pads and warps your rotors.
 

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If it continues to get worse, I'll try spraying some penetrating oil in there and see if it helps.
Do not do this.

I believe there was a recall, and they cleaned the plenum, removed the drain grommets, and replaced the cabin filter seal.

If you have the booster referred to in the NHTSA Action, you should be able to remove the intake filter and suck the water out from the back section of the booster.

Keeping the plenum drains free is the responsibility of the driver, water won't get into the booster if they are clear.

From what you say, it would appear that the rod (or anything in the brakes) is not sticking, but the brakes badly need bleeding.
 

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Discussion Starter · #18 ·
Booster continues to give me problems. I now believe I have either a crack or hole in the diaphragm of the booster, causing a vacuum leak. I believe this for two reasons:

1. The booster's performance is erratic / not consistent
2. I just tripped a P0171 code (system too lean).

Last Friday was our first warm day in several weeks, so I decided to see how sticky the rod was. I tried several hard stops in the parking lot to see if I could stick the pedal. Each time I was able to get the pedal stuck on a hard stop. I would release it by reaching down into the footwell and pulling the pedal back up. One time I pulled the pedal back too hard, and caused the plastic threads on the brake switch housing to slip up a few threads in the holder. I had to remove the lower console trim to re-adjust the pedal switch, since the brake lights would not shut off.

I notice now that the booster will intermittently 'grab on' as if the vacuum is causing the booster to actuate slightly on its own. I believe that there is a vacuum leak in the deaphragm itself, or one of the seals on the pushrod is not functioning properly. Feathering the pedal brings things back to normal.

I believe that this leak is allowing atmospheric air to enter the vacuum system, throwing off the fuel mixture, which tripped my P0171 code.

I know there's lots of vacuum hoses that can cause that code, but I just went over this motor with a fine tooth comb a few weeks ago and replaced several worn/broken vacuum lines. I don't believe the vacuum leak is from anywhere else but the booster. Another reason I believe I have a leak is that when I shut off the engine, the brake pedal comes back up a few miilimeters, as if there was a partial vacuum on the pedal-side of the booster too. That should NOT be the case, the pedal side of the diaphragm should be at atmospheric pressure only.

I'm going to purchase and install a replacement booster.
 

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It is easy to check for a leak in the booster, see Bentleys or Haynes manual.

There is normally vacuum both sides of the diaphram.
When the pedal is pressed, a valve between the 2 chambers is closed, and a valve in the rear chamber is opened to atmosphere.
That is a simple explanation, the overall operation is actually a bit more complicated.


You need to approach this with a more open mind, you haven't provided any evidence of a fault in the booster.
A leak in the booster will not cause the brakes to be applied. This it most likely something restricting the full return of the pedal.
First check the panel above the pedals, then anything that might restrict pedal movement.

Then properly bleed the brakes.
 

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If your booster works erratically, replace it. It might become "non responsive" at the exact time you need it. Call the dealer first and see if they would replace it. Probably not, but a phone call is cheap. Then you can address the P0171, if you still have it.
 
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