??Vac. Goes Down When Press Brakes??

[WhiteTsiAwd]

Well i noticed yesterday that when i pump on the brakes at idle, my Vac. goes down to 9-10 from a normal 15-16? I havent a clue why it does this and any help would be great.

Thanks,
Cody

 

[BigBADGSX]

your brake booster is connected to the intake manifold....there is a really big vac line going from there. the booster uses some vac from the manifold to help it out.

any more questions?

 

[Defiant]

The booster _is_ vacuum. If it goes every time, the check valve in the vacuum line to the booster may be bad, but that's very rare. The valve lives inside the hose.

 

[WhiteTsiAwd]

I'll check it and see if i can find anything bad.
Thanks.