Originally Posted by stephenson

I learned a trick about 20 years ago on a BMW 2002 I had which had an external tstat ... have used it on every tstat I have installed since then - I and several other BMWCCA members went through dozens prior to finding ones that actually operated properly - someone came up with this idea and it appeared to work then.

I drill 3-4 tiny holes around the perimeter - the portion of the tstat that is thin (the part that moves) .. while I don't KNOW if this had made a difference since then in the 10-15 tstats I have replaced or simply removed and then reinstalled, I have not had a tstat that didn't appear to operate properly since then.