Got one of these second hand and was working fine for a few months, then yesterday the phssst started to get shorter and now it is not dumping under 4.5k.
Previously dumping easily at 3.5k and a much longer phssst.

Managed to get outer casing off however to get to the spring at the rear section, 2 of the allen bolts/ nuts are stripped & stuck.
So sprayed moving part with wd40 whilst pushing in and out, refitted and still the same.

car is 03 sti running approx 360/360

Any ideas??

 

try stretching the spring mines done the same took it scooby clinic and thats what they told me to do. i havent got round to doing it yet though

 

can't open the rear section to get at the spring as some of the nuts on the allen bolts are rounded.

Can you buy a new spring / internals/ allen bolts for these dump valves?

 

i think so, im not 100% sure though i no you can buy new filters to change the sound