No I did not have to tighten up the wire to get the shaft to seal. Of course the plunger has to be clean without scratches or pits, I did use a little rod wax on the shaft (Vaseline). If the diaphragm or capillary tube had a leak then the thermostatic control is not going to work. It’s filled with a fluid (unknown) and cannot be refilled or recharged. You can test it by placing it in the freezer and giving it about 15 minutes, it should collapse if it doesn't then you have a leaker. You will have to play with the adjustment of the cam to get the best operation when you turn the heat control.
As far as how well it works, I’d say that it does stop most of the water flow. But as I said the internal valves don't seal all of the water from circulating and a little will leak thru even when fully closed. It does seem to control the heat to some degree but it has a very slow response. Because there is still a little water flow when the temp control is turned of a shutoff was often place in one of the lines for summer use. The vendors sell several types of shutoffs, one is screwed into the water pump and others are inserted into the heater hose and can be controlled by a cable.
Don't expect it to control the heat like you 2010 Chevy truck.
Denny Graham
Sandwich, IL
