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.
One of the most common symptoms associated with worn engine mounts are impact noises coming from the engine bay. Worn, damaged, or broken motor mounts can cause clunking, banging, and other impact type sounds as a result of the weight of the engine shifting excessively to the point of contact.