drain some coolant, unbolt the bolts holding the housing on inlet pipe, remove t-stat from housing. Get some water up to boiling turn off the heat lower the t-stat in on a wire or something watch for it to open. Or you could just skip this step and buy a new one from the dealership they are like $2 or so. But make sure when re installing you put it back in the same as it was it can go in backwards or upside down make sure the jiggle valve is on the top half