Bad Brake Booster, or M.C.?

[MitsuMannyC]

I've searched and can't seem to find any leads on this braking issue that I'm having on my 97 Tsi AWD. Little background on the car, I bought it as a shell last fall and just finished dropping the motor in, and working all the minor issues as they came.

When I'm driving the car, and coming to a stop, my first and second initial pump of the brake pedal seems completely fine. its after about the 3rd pump or so that the pedal becomes rock solid and the car seems to "glide" and not want to slow down unless I really put a lot of pressure into the pedal, in which it finally decides to slowly come to a stop. It doesn't feel like air in the system, (no mushy pedal) as I did one hell of a job bleeding them with a mighty vac.

It seems to me that my booster, or master cylinder might be bad?? But i don't want to keep throwing money at it without a better idea of which can possibly be my culprit. This is a NON ABS 97 AWD 5spd Talon. I installed new pads and rotors all around, and fully bled the whole Brake system (in the correct order). I will say that this is my first non abs car.. my 99 Gsx has ABS. But I doubt non ABS cars are suppose to brake and slow down as sketchy as my Talon is doing .. any help guys?

 

[Turbo2g]

If you open the hood and run the car at idle pushing on the brake, can you hear any hissing noise? That would be a clue towards the booster. If you pump it up to where it's really hard and hold, does the peddle ever sink or go lower? That would be a master cyl clue.

 

[ist dwa]

Sounds like a bad brake master, sound like the line pressure is pushing through a seal. It wouldn't be the worst thing in the world to change your 20 year brake master cylinder even if it isn't the problem...you know that safety first thing oh and totaling your car.

 

[MitsuMannyC]

If you open the hood and run the car at idle pushing on the brake, can you hear any hissing noise? That would be a clue towards the booster. If you pump it up to where it's really hard and hold, does the peddle ever sink or go lower? That would be a master cyl clue.

I have not tried pushing the brake, while the car is ideling, so I will try that tomorrow when I get back to the garage. As far as holding the pedal when it's firm, it does NOT sink after it gets rock solid which led me to believe the master was fine, and that my bleeding job was successful.

 

[Marchev]

Your description leads me to a bad booster. If the pedal is hard and not sinking either the booster is not working or the vacuum source going to the booster is compromised.

For comparison, try disconnecting the booster and capping the nipple, then go for a short drive. If the pedal feels exactly like how you're describing it happen randomly then you found your issue

 

[ceedawg]

I had this problem and it was the brake booster. I did all the tests everyone suggests including using a bigger MC changing the brake booster vacuum line and nothing changed. I took the brake booster out and the seal on the other end of the booster was completely deteriorated around the pin so this just created A vacuum leak not allowing the booster to work properly. No more hard pedal nor gliding brake stops.Changed the booster which had a nice clean round rubber seal and all is good now.

 

[silvreclips]

Here is one way to check a brake booster. With the car off, pump the brake peddle up until its firm. Hold the brake pedal and start the car, if the pedal sinks further then the booster is working. Keep in mind it may still be leaking some and working 100%

 

[ceedawg]

Here is one way to check a brake booster. With the car off, pump the brake peddle up until its firm. Hold the brake pedal and start the car, if the pedal sinks further then the booster is working. Keep in mind it may still be leaking some and working 100%

Did that same results. Car still had issues stoping. Had to fully investigate the booster and the issue stared me right in the face once I had it out the engine bay. Blown booster seal around the pin. Crumbled ,deteriorated. I had pics and post on it . Check my posts.

 

[arrowhead]

I would change the master cylinder anyways, the car has been sitting for a good while, after you change it, also check your brake hoses.
Also check for leaks behind booster.