Hi any body out there able to help me with a 330 Desoto Hemi thermostat question. The water bypass attaches to the thermostat housing. I assume the Desoto thermostat seals above the bypass. My motor came without a thermostat so without one Im only guessing The bypass allows water to circulate through the block when the thermostat is closed. If the incorrect thermostat was installed them it would cause problems with the water flow Thanks Peter