How do blow off valves work?

I just need some idea of how the blow off valve works... So that i can fix mine..

Lately my blow off valve has been leaking under full boost..

I took the valve off and i see where it mounts to the intercooler pipe a snap ring keeping the whole assembly together, as far as i can tell there is only a spring on top of the solenoid keeping the blow off valve in the closed position. As the pressure builds the valve needs to open but the line on top keeps extra pressure as well as the spring.. to keep it closed? When the throttle lets off The boost from the compressor wheel as the throttle plates close the boost increases and opens the solenoid.... Kind of confused as to where the vacuumn lines come into play? Only reason i can think of it leaking would be weak spring pressure? Can i just adjust the spring pressure with the screw on top to stop the leaking? Or why else would it leak? I am going to take the snap ring out and investigate further but until then any input would be great!

Evan

 

I believe it has two references, one before the TB and one after. when the throttle closes, the engine creates vacuum after the TB but is still under boost before it. The pre TB reference is the I/C piping flange and is routed through a hole to the atmosphere when the pressure difference is less than the spring's pressure.

 

Why do blow off valves start leaking? The spring gets weak? And you just need to put increased tension on it?

Evan

 

might just be a crappy knock off blow off valve, or the o-ring underneath might be pinched or something.

 

 

Its a blitz blow off valve, and i took it all apart today learned how it ticks and cleaned it all up should be good to go now!