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.
When the air pump check valve fails, it can lead to a variety of problems, notably a significant increase in the vehicleâs tailpipe emissions. Usually, when the air pump check valve fails, it will display a few symptoms that may alert the driver of a potential problem that should be inspected.