Hey guys I have a 2009 GP tjet sporting.

I noticed that when my car is on but stationary, if I pump the brake pedal it will make a hissing noise as if air is escaping with every press?

Is this normal?

any advice on what it is or how diagnose would be great

Hi Emerson,

the brake assistance consists of a menbrane enclosed in an housing, when you push the pedal, vacuum, from engine manifold on petrol and from pump on a diesel, is applied on this menbrane so assists you in braking. The other side of the menbrane is at air to allow it to move; you probably hear that air entering the housing when the car is stopped and quiet...

BRs, Bernie

Nothing to worry about until you loose braking assistance, the pedal will be much firmer and will take much more force to translate the same braking force to the tires.