Definition of quantal. 1  1 [Latin quanti how many, plural of quantus] : of, relating to, or having only two experimental alternatives (such as dead or alive, all or none) 2  2 [quantum] : of or relating to a quantum.
3. Engine movement. Another symptom of bad or failing engine mounts is an engine that moves in the engine bay. If the engine mounts are in good condition, they should be able to secure the engine firmly in the engine bay.
A thermostat fails âopenâ if the return spring breaks or debris prevents the thermostat valve from fully seating or closing; allowing a steady flow of coolant to the radiator, overcooling the engine. 1  This results in poor warm up and heater performance, increased engine emissions and reduced fuel economy.