My dump valve doesnt seem to 'dump' everytime i take my foot off the accelerator? ,But as i dont really know exactly how they are supposed to work i dont know if this is correct or not, my mates seems to dump the air alot more than mine?
Could someone please give me some help and advice, i have put a squirt of the wd on the piston incase that was sticking,

 

Can you adjust the spring pressure ? If not try a lighter spring

 

I can turn the top bit but whether this does anything im not sure its a turbox valve,