Is engine a common noun

Yes! Common nouns = Nouns name people, places, and things. Every noun can further be classified as common or proper. A common noun names general items.

Go into the kitchen. What do you see? Refrigerator, magnet, stove, window, coffee maker, wallpaper, spatula, sink, plate-all of these things are common nouns.

Leave the house. Where can you go? Mall, restaurant, school, post office, backyard, beach, pet store, supermarket, gas station-all of these places are common nouns.

Go to the mall. Who do you see? Teenager, grandmother, salesclerk, police officer, toddler, manager, window dresser, janitor, shoplifter-all of these people are common nouns.

The important thing to remember is that common nouns are general names of everyday items.