Scary brake problem

I have an '02 Jetta auto with 75k miles that has just developed a brake problem. I'm very easy on this car and still have the original brake pads. I had a bad brake switch replaced under warranty a few months ago and at that time had the brake fluid changed and brakes bled. Brakes felt and worked fine.

Yesterday I was sitting at a light with my foot lightly on the brake when the pedal suddenly moved away from my foot towards the floor. It then popped back with a hissing sound. This happened a few more times during the day. The last time it happened I was slowing down to a stop light at about 20mph. The pedal pulled away from my foot towards the floor and almost locked the brakes for a split second before popping back with the hissing noise. If anyone was too close behind me I would have been rear ended.

Any thoughts on what this may be caused by? Booster problem? MC? Anyone have a similar experience?

bad booster

rs_us999:

I have the exact same symptoms on my 2002 TDI. I suspect either the booster or the master (obviously!). The only reason I kind of wonder about it being the master is that the pedal is mushy.

Any ideas from the group?

Neil Deshpande

neil

yeah, my pedal feels a littly mushy too now. I spoke with the stealership today. The mechanic said it could be the master or the booster or both. I'm bringing it in on Wed. I think its going to be expensive. Anyone have any idea on the cost of a MC and/or booster change?

Listen carefully cause it will save you a bunch of money... your master is fine... these are classic symptoms of a bad brake booster. Replace the brake booster and everything will be fine, I know because this happened to me. http://forums.tdiclub.com/showthread.php?t=104656 That was almost 200,000km ago and master is still going great!

Thanks Grizz and Chris

How hard was the booster swap? Is it pretty involved? It looks like you have to remove the MC to get at it? I'm pretty handy, but I won't be doing anything as complicated as a TB change. Did you buy the parts from the dealer?

Sounds like another booster problem.

http://forums.tdiclub.com/showthread.php?t=188741

Its a pain and you need a special tool to do it... this is in the How-To's http://forums.tdiclub.com/showthread.php?t=87039 Hope it helps.

Dont change the booster until you try lubricating up under the brake pedal. Pull back the white plastic cover and spray some lithium grease in there. It will fix it right up.

Yelram
Thanks!!!!!!!
I did what you said and I have not had the problem in 2 days. I can't believe this is a permanent fix, though.

rs_us999 said:

Yelram
Thanks!!!!!!!
I did what you said and I have not had the problem in 2 days. I can't believe this is a permanent fix, though.

Click to expand...

It totally is, i've put like 7000 on since it happened on mine. I guess its called something like an "atmospheric switch" or something that gets jammed without lubrication. I took it to the dealership and they were ready to change the booster. I also had a problem with my instrument cluster not reading the PRD123 or the odometer. The dealership said new cluster. I said contact cleaner. Its worked fine ever since.

Thanks again. I'll run with the lubrication fix for now. It's saving me a ton of money. I'll let you know if I have any more problems with it. I agree with you on the dealer's eagerness to replace your cluster. These guys don't fix anything - they just replace parts. They actually don't have the financial incentive to fix things - they make more money on the part and charge you the labor time anyway.

Keep us posted... I have heard of this and tried it myself to no avail but if it works thats great!

I had a vacuum hose leak that affected the brake booster. In my case the effect was a hard pedal that resulted in very poor braking power.

I do not know the symptoms of a bad brake booster, but it seems to me that it should be increased brake effort and much longer stopping distance. A pedal that sinks to the floor just doesn't seem like the result of a failed brake booster. Am I completely wrong?

A pedal that sinks to the floor just doesn't seem like the result of a failed brake booster. Am I completely wrong?

Click to expand...

Sometimes the booster goes bad in a way that causes it to actually pull the pedal down with out anyone actually pushing on it. It won't actually go to the floor but it will move down on its own. It sounds like that is what was happening to rs_us999.

Matthew_S
You are right. The pedal doesn't sink all the way to the floor but pulls away from my foot on a partial pedal press. It then "pops" as if it is releasing pressure (probably vacuum) which causes that hissing noise. Then the pedal returns to normal position and feel. The whole process is quick, maybe 1/2 second. Fortunately this hasnt happened since I tried Yelram's fix.

10 months later and the problem still has not returned after 10,000+ miles! Thanks Yelram

On another note, now I am having suspension and auto transmission problems.. i think I will soon be an ex tdi-er. just too many problems with this car at only 88,000.

in my case the vacuum hose had a crack in it or leak which made my pedal hard after a couple of pumps and gave almost no braking. i replaced it with a high grade one and all was fine.

i dont know why vw would use such a cheesy plasticky hose instead of rubber when theyre known for quality.

Actually - The plastic hose stands up better to vacuum than rubber which can get "sucked in" and essentually close off the vacuum. Because of this, VW has used the hard-plastic for vacuum lines for over 20 years.

I see you are in SoCal - I would bet that the underhood heat tends to degrade the plastic materal. Here in Vermont, we are lucky if there is any underhood heat ... We have to plug in our TDIs just so the heater works - LOL

I bet you have never had to deal with "flat spots" on your tires due to sitting all night in -20F temparture. (Or sublimination on the windshield) At those temps... a plastic bumper can shatter like glass if you acidently bump into somthing while parking.

..I guess we each have to suffer from extreme tempartures in our own way.

Hi All, Mr. Cheap-O's fix for me was to put a bungy cord from the pedal around the steering column. Recommended - NO, but... Effective - Yes.
Happened two months before inspection, took it off for inspection and haven't replaced (4 months)

here is a photo of my bad booster hose http://forums.tdiclub.com/showthread.php?t=209173

Nocky said:

here is a photo of my bad booster hose http://forums.tdiclub.com/showthread.php?t=209173

Click to expand...

You mean this?