ca86108

Hello,

I have a 2012 Turbo S with PCCB's. Today, I was driving to work and it was pouring rain and cold out. When I was about to hit traffic, I hit the brake pedal. It felt like it didn't want to go all the way down and the car didn't brake all the way, it kind of slid forward. I tried again later on and the same thing. It seems that the pedal is very hard and you can't push it down as much. Does anyone know what the reason is?

HenryPcar

Try stepping on the brake pedal and pump it a few times WITHOUT STARTING THE CAR. The pedal should firm up rock hard. Then while stepping on the rock hard pedal, then crank the engine to start. Your pedal should sink with the brake bolster on. If the pedal does not sink, then your bolster has a problem.

o7silverturbo

Could be either your brake booster is going bad/is bad, brake booster check valve isnt working or your vacuum pump is not working.

If you pull the line off the brake booster and put your finger over the hole you should feel suction. (really should use a vacuum gauge but this is a quick test)

If you feel suction then you will need a hand pump to test the booster

gsxrjjordan

Sounds like an ABS problem if not a vacuum problem - no lights on the dash?

theanalyst

Massive thread revival. I have got a similar issue but its only when at idle, so if for example I am coasting in stop start traffic, suddenly I can find the pedal has gone like wood. A little blip on the throttle and its fine again.
I tested the vacuum pump and it was above the required vacuum (dont recall the reading as it was ages ago) , so now I'm stuck wondering what it could be. Does anyone have any suggestions on further testing. I was thinking it could be brake booster or booster check valve that are going bad? Otherwise I guess a vacuum leak,. This is really p*ssing me off, any suggestions welcomed. Was thinking to test the brake booster with a vacuum hand pump, does anyone have a picture of which line it is in the trunk that goes to the brake booster? Im pretty sure I am looking at the right one. 2007 997 tt tiptronic thanks

saabin

Pretty sure its the one circled in red.. THis pic is from when I did my engine drop 2 years ago for my coolant pinning.. The line running back into the engine compartment goes to the brake booster.

theanalyst

AH perfect. Thanks, yeah looks the one, with that circlip iirc.

Slightly stuck with the best way to tackle the issue, vaccum pump is working correctly, I guess that leaves either that line with a leak in , or a faulty brake booster or valve? Just about the only part of the damn car I have not replaced lol. Dont want to pony up for a booster without knowing 100% thats the issue I guess.
Any ideas for proving the fault anyone?

thanks

solts

^^^Your problem sounds different than OP's, which TBH is just how these brakes work (or don't work rather) if they're cold and wet. Anytime it's raining outside, I make sure to try to get heat in them as soon as possible in case I actually need to use them because the legit don't work otherwise