Ron
Enthusiast
A little Thermostat Trivia:
Viper thermostats are a “movable sleeve” design, rather than the more conventional "Weir" type. They were originally designed for diesel truck applications and can flow approximately 150 gallons per minute vs. conventional automotive thermostats that flows approximately 30 gallons per minute.
A Thermostat’s temperature rating can refer to either the “start to open” temp, “nominal” temp or “full open” temp. In the case of our stock GEN I & II 195 degree thermostat, the number refers the opening temp. Full open does not occur until 219 degrees. In the case of the Mopar Performance 180 degree unit, the 180 refers to the nominal temp, i.e. roughly the midrange point between beginning of movement and full open, meaning that 180 degrees is the temperature that the thermostat tries to maintain.
When new, they operate with an accuracy of +/- 2 degrees. The full stroke is .450” and is calibrated for that stroke by dimpling the copper pellet, thereby squeezing the internal pellet wax and moving the piston to the correct position.
There is an internal ramp mechanism that prevents over stroking if overheated and provides a bypass to the wax as it expands, however the thermostat could become permanently damaged if exposed to excessive temperatures.
The design life of most thermostats is predicated on the longevity of the rubber diaphragm and internal rubber components. In the case of our Viper Thermostats, that design life is 30,000 cycles. As the rubber components age, they begin to limit the travel of the valve. This causes later valve openings which become observable by noticing gradually increasing coolant temperatures. Catastrophic failures, resulting from wax leakage, are fortunately relatively rare.
Accurate temperature activation testing can not be performed on the kitchen stove. While it is useful in confirming functionality, the thermostat must be tested at 15lbs. of pressure in order to calibrate properly. There is no accurate conversion factor to test accuracy of thermostat at ambient pressures.
Viper thermostats are a “movable sleeve” design, rather than the more conventional "Weir" type. They were originally designed for diesel truck applications and can flow approximately 150 gallons per minute vs. conventional automotive thermostats that flows approximately 30 gallons per minute.
A Thermostat’s temperature rating can refer to either the “start to open” temp, “nominal” temp or “full open” temp. In the case of our stock GEN I & II 195 degree thermostat, the number refers the opening temp. Full open does not occur until 219 degrees. In the case of the Mopar Performance 180 degree unit, the 180 refers to the nominal temp, i.e. roughly the midrange point between beginning of movement and full open, meaning that 180 degrees is the temperature that the thermostat tries to maintain.
When new, they operate with an accuracy of +/- 2 degrees. The full stroke is .450” and is calibrated for that stroke by dimpling the copper pellet, thereby squeezing the internal pellet wax and moving the piston to the correct position.
There is an internal ramp mechanism that prevents over stroking if overheated and provides a bypass to the wax as it expands, however the thermostat could become permanently damaged if exposed to excessive temperatures.
The design life of most thermostats is predicated on the longevity of the rubber diaphragm and internal rubber components. In the case of our Viper Thermostats, that design life is 30,000 cycles. As the rubber components age, they begin to limit the travel of the valve. This causes later valve openings which become observable by noticing gradually increasing coolant temperatures. Catastrophic failures, resulting from wax leakage, are fortunately relatively rare.
Accurate temperature activation testing can not be performed on the kitchen stove. While it is useful in confirming functionality, the thermostat must be tested at 15lbs. of pressure in order to calibrate properly. There is no accurate conversion factor to test accuracy of thermostat at ambient pressures.
