MBMB

I have my vacuum check valve (p/n 928 355 660 03, the black t-shaped one that plugs into the rubber seal on the brake booster) off the car. It doesn't seem to be "checking" -- air flows easily from each of the three orifices to the others. How should this behave?

Also, when I had the check valve installed in the booster I blocked off the orifice that goes toward the intake, and tried to draw a vacuum from the orifice that goes toward the secondary vacuum system. I was not able to draw a vacuum. Does this indicate a booster vacuum leak?

Is a brake booster vacuum leak reparable, or does it require a replacement booster? PET shows the following p/ns for the booster:


Thanks,
Mark.

MBMB

Correction -- check valve closes, but only when a large volume of air moves from the engine side to the booster side.