Fixing my thermostat, How I did it Options

[MrKona]

There was a recent thread about thermostats... it reminded me that the thermostat that came with the engine I'm building was broken, and I had to either buy a new, used one, or see if I could fix the one I have. I followed the informative article by Richard Atwell with good results. Ratwell link

My thermostat had sprung a leak somewhere which eliminated the negative pressure vacuum a functioning thermostat holds at room temperature. The thermostat is supposed to measure around 35mm in length at room temp, mine measured around 46mm, which is the normal expanded state length. I examined it closely and could not find any cracks around the perimeter, so I assumed there must be a break at a brazed surface. I was in luck, it was fixable!

Just for kicks, I placed it in a hot water bath approximately 180 degree F, and there was no significant change in length, pre- to post-bath.

[MrKona]

While I had the top off, I blew out any debris with a little air. I then fluxed the rim, mounted the thermostat gently back in the vise and brazed the lid back on. (No picture of that one, but you can imagine...). I left the small hole in the lid open.

Next step was to compress the thermostat down and wrap it in metal wire to keep it compressed.