Explain this brake probem...

[sk8jam007]

I just got a JDM engine in my 1990 tsi awd, and just got it running after sitting for about 3 months. I go to drive it about 10 miles to another garage when all of a sudden about half way there the brake pedal goes solid and it's all the way up. The car would still brake but you really had to push on it in order for it to do anything. Then about 100 feet from the garage the brakes locked up. The only way I could get it to go anywhere was to loosed one of the fittings on the master cylinder and let the pressure out of the lines. What could this be? I'm stumped, and so is everyone else I've talked to. I'm going to try and replace the brake master cylinder because that is the only logical thing that I think it could be. What do you tihnk?

 

[jtmcinder]

You screwed up the valve between the intake plenum and the booster.

- Jtoby

 

[Mike1992]

Accidently adjusted the brakes when you meant to adjust the clutch. I know I cant be the only one thats did this.

 

[sk8jam007]

Thanks for the responses, although I think I may have another problem unless someone can tell me otherwise. The brakes did work for about 5 miles, and then the pedal went solid, then about 5 miles later they locked up. Could this still be caused by a vacuum issue, or is it something else?