[djs]

I think there is only supposed to be one spring on the rod that holds the flaps open. I recall only one on my Vanagon and Porsche 2.O, as well as every other Type IV motor I've seen.

There is, however, an adjustment on the thermostatic bellows itself. There should be a threaded section on the cable end where it attachs to the bellows. You use this to lengthen or shorten the cable, thus affecting the amount of "pull" on the flaps, which are held in the open position by the single spring on the rod. In operation, the flaps are held "closed" by the pull on the cable (which should be greater than the spring tension), but transition to "fully open" as the bellows expands and relaxes the cable. Another adjustment point for this mechanism (I think) is the mounting bracket for the bellows. I think the holes for the bracket where it mounts to the case may be slotted, allowing for back & forth placement of the bellows position.