My understanding is there is a bi-metal strip inside, so when it's strapped to the steel water pipe on the back of the block, with the pipe heated by the water the disc inside reveals a larger venturi.
So having been warned it's a sod to get to once it's built up and in the car, I thought I'd check it's operation beforehand. I've put it on a radiator I can hardly touch at work (as it's that hot) on a nice flat surface, and although there is movement, it's not moving a deal.
What am I looking for? At the minute going from cold, it's leaving say 5% open (although it's a strange shape) to fully open with heat? Mine ain't moving that much.
I understand that the heat will move the bi-metal strip and therefore the disc & send a signal to the ECU, but what function does linking it into the boost side of your induction have? Is this just to aid the warming up process? Is that why I can't get it to open fully?
Basically, I don't get it - and I'm sure it's very simple!