Maxim-X Thermostat Replacement

Comparing Dimensions
When I found the Motorad 2040-180, I was fairly certain I had found the perfect replacement thermostat for the original Yamaha 3GM-12410-00-00. My previous comparisons were made with the new thermostat still inside its packaging. Now having bought the new thermostat, however, I was able to remove it from its packaging to take some more accurate measurements for a final comparison and documentation.

As expected, all dimensions of the new thermostat seemed to work. The outside diameter was only 0.01" smaller than the original, which would easily be absorbed by the rubber ring gasket. The aperture was only 0.02" larger than the original so coolant flow wouldn't be restricted if valve sweep was similar. Both the top and bottom sections of the new thermostat extended less than the original (not as tall & not as deep) and all critical widths were also smaller, meaning the new thermostat was physically capable of replacing the original, as expected.

All conceivable measurements of both the original and the replacement thermostats were recorded as shown in the following plan view and profile view images:

Although the original Yamaha thermostat and the replacement Motorad thermostat aren't very similar in appearance, the magnitude of critical physical dimensions are very comparable, making the Motorad thermostat the perfect alternative, physically. The only remaining question was whether the new thermostat would behave like the original one under operating temperatures. Some operational testing still had to be done, just to be certain. [ »»» Testing ]